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Effects of elevated CO2 and temperature on seed quality

Published online by Cambridge University Press:  30 March 2012

J. G. HAMPTON ,
B. BOELT ,
M. P. ROLSTON  and
T. G. CHASTAIN
J. G. HAMPTON*
Affiliation:
Bio-Protection Research Centre, Lincoln University, Lincoln 7647, New Zealand
B. BOELT
Affiliation:
Sciences and Technology, Aarhus University, DK 4200 Slagelse, Denmark
M. P. ROLSTON
Affiliation:
AgResearch Ltd, Lincoln 7647, New Zealand
T. G. CHASTAIN
Affiliation:
Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331-3002, USA
*
*To whom all correspondence should be addressed. Email: john.hampton@lincoln.ac.nz
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Summary

Successful crop production depends initially on the availability of high-quality seed. By 2050 global climate change will have influenced crop yields, but will these changes affect seed quality? The present review examines the effects of elevated carbon dioxide (CO2) and temperature during seed production on three seed quality components: seed mass, germination and seed vigour.

In response to elevated CO2, seed mass has been reported to both increase and decrease in C3 plants, but not change in C4 plants. Increases are greater in legumes than non-legumes, and there is considerable variation among species. Seed mass increases may result in a decrease of seed nitrogen (N) concentration in non-legumes. Increasing temperature may decrease seed mass because of an accelerated growth rate and reduced seed filling duration, but lower seed mass does not necessarily reduce seed germination or vigour.

Like seed mass, reported seed germination responses to elevated CO2 have been variable. The reported changes in seed C/N ratio can decrease seed protein content which may eventually lead to reduced viability. Conversely, increased ethylene production may stimulate germination in some species. High-temperature stress before developing seeds reach physiological maturity (PM) can reduce germination by inhibiting the ability of the plant to supply the assimilates necessary to synthesize the storage compounds required for germination.

Nothing is known concerning the effects of elevated CO2 on seed vigour. However, seed vigour can be reduced by high-temperature stress both before and after PM. High temperatures induce or increase the physiological deterioration of seeds. Limited evidence suggests that only short periods of high-temperature stress at critical seed development stages are required to reduce seed vigour, but further research is required.

The predicted environmental changes will lead to losses of seed quality, particularly for seed vigour and possibly germination. The seed industry will need to consider management changes to minimize the risk of this occurring.

Information

Type
Climate Change and Agriculture Research Papers
Information
The Journal of Agricultural Science , Volume 151 , Issue 2 , April 2013 , pp. 154 - 162
Creative Commons
Creative Common License - CCCreative Common License - BYCreative Common License - NCCreative Common License - SA
The online version of this article is published within an Open Access environment subject to the conditions of the Creative Commons Attribution-NonCommercial-ShareAlike licence . The written permission of Cambridge University Press must be obtained for commercial re-use.
Copyright
Copyright © Cambridge University Press 2012

INTRODUCTION

With global change, atmospheric carbon dioxide (CO2) concentration is predicted to rise from today's value of c. 370–550 ppm by 2050 and could reach between 730 and 1010 ppm by 2100 (Solomon et al. Reference Solomon, Qin, Manning, Chen, Marquis, Averyt, Tignor, Miller, Solomon, Qin, Manning, Chen, Marquis, Averyt, Tignor and Miller2007). This, combined with other atmospheric changes, is projected to increase global mean temperatures by 1·4–5·8 °C (Houghton et al. Reference Houghton, Ding, Griggs, Noguer, Van Der Linden, Dai, Maskell and Johnson2001). Jaggard et al. (Reference Jaggard, Qi and Ober2010) concluded that CO2 enrichment was likely to allow yield increases of c. 13% in most C3 crops, but yields of C4 crops are not expected to change. However, increasing temperatures may negate these increases in C3 crops, particularly if they occur during reproductive growth (Allen & Boote Reference Allen, Boote, Reddy and Hodges2000; Wheeler et al. Reference Wheeler, Craufurd, Ellis, Porter and Prasad2000). Gornall et al. (Reference Gornall, Betts, Burke, Clark, Camp, Willett and Wiltshire2010) noted that extreme weather events are more likely to occur in the changed climate of the future, and predicted that over much of the world's crop land, maximum daily temperature highs may be increased by around 3 °C by 2050.

A major challenge ahead for those involved in the seed industry, therefore, is to provide cultivars that can maximize future crop production in a changing climate (Ainsworth et al. Reference Ainsworth, Rogers and Leakey2008a; Bruins Reference Bruins2009; Ceccarelli et al. Reference Ceccarelli, Grando, Maatougui, Michael, Slash, Haghparast, Rahmanian, Taheri, Al-Yassin, Benbelkacem, Labdi, Mimoun and Nachit2010). Ainsworth et al. (Reference Ainsworth, Beier, Calfapietra, Ceulemans, Durand-Tardif, Farquhar, Godbold, Hendrey, Hickler, Kaduk, Karnosky, Kimball, Körner, Koornneef, Lafarge, Leakey, Lewin, Long, Manderscheid, McNeil, Mies, Miglietta, Morgan, Nagy, Norby, Norton, Percy, Rogers, Soussana, Stitt, Weigel and White2008b) considered that this will be possible within a decade.

Successful crop production in any environment depends initially on the quality of the seed being sown. The term ‘seed quality’ is used in practice to describe the overall value of a seed lot for its intended purpose (Hampton Reference Hampton2002), and includes the components of species and cultivar purity, seed mass (size), physical purity, germination, vigour, moisture content and seed health. The present review examines the effects of increased CO2 and increased temperature on three of these seed quality components, seed mass, germination and vigour.

SEED MASS

Within the seed industry, seed size is commonly denominated by the mean seed weight, often expressed as ‘thousand seed weight’, the weight of 1000 seeds of the seed lot. However, seed size refers to volume, while seed weight and seed mass refer to density, which are different traits (Castro et al. Reference Castro, Hodar, Gomez and Basra2006). Seed mass in crop cultivars is considered the least variable of the seed yield components because of plant breeding for increased seed uniformity (Almekinders & Louwaars Reference Almekinders and Louwaars1999) and the removal of small seeds during the seed cleaning processes. Factors affecting seed mass, including genetic factors, water availability and nutrient availability were reviewed by Castro et al. (Reference Castro, Hodar, Gomez and Basra2006).

Increased atmospheric CO2 concentrations might be expected to increase seed mass because of increased plant assimilate availability (Jablonski et al. Reference Jablonski, Wang and Curtis2002), but the reported effects of elevated CO2 are highly variable among species (Miyagi et al. Reference Miyagi, Kinugasa, Hikosaka and Hirose2007; Hikosaka et al. Reference Hikosaka, Kinugasa, Oikawa, Onoda and Hirose2011). Different studies have reported seed mass to increase (Musgrave et al. Reference Musgrave, Strain and Siedow1986; Baker et al. Reference Baker, Allen, Boote, Jones and Jones1989; Dijkstra et al. Reference Dijkstra, Schapendonk, Groenwold, Jansen and van de Geijn1999; Steinger et al. Reference Steinger, Gall and Schmid2000; Quaderi & Reid Reference Quaderi and Reid2005), show no change (Edwards et al. Reference Edwards, Clark and Newton2001; Prasad et al. Reference Prasad, Boote, Allen and Thomas2002) and decrease (Huxman et al. Reference Huxman, Hamerlynck, Jordan, Salsman and Smith1998; Smith et al. Reference Smith, Huxman, Zitzer, Charlet, Housman, Coleman, Fenstermaker, Seemann and Nowak2000; Wagner et al. Reference Wagner, Luscher, Hillebrand, Kobald, Spitaler and Larcher2001) in response to elevated CO2. Jablonski et al. (Reference Jablonski, Wang and Curtis2002) conducted a meta-analysis of 184 CO2 enrichment studies from 79 species and found a mean 4% increase in seed mass, with the response being greater in legumes (+8%) than non-legumes (+3%), and absent in C4 plants. Considerable variation in seed mass in response to elevated CO2 was also reported within species. Hikosaka et al. (Reference Hikosaka, Kinugasa, Oikawa, Onoda and Hirose2011) reported the enhancement ratio of seed mass per plant (seed mass in elevated CO2/seed mass in ambient CO2) ranged from 0·75 to 4·45 in rice (Oryza sativa L.), from 0·93 to 1·87 in soybean (Glycine max (L.) Merrill), and from 0·88 to 2·07 in wheat (Triticum aestivum L.).

Jablonski et al. (Reference Jablonski, Wang and Curtis2002) found a 14% reduction in seed nitrogen (N) in response to elevated CO2 averaged across all 79 species in their analysis, although there was significant variation; seed N was not reduced in legumes, but was reduced in non-legumes. Hikosaka et al. (Reference Hikosaka, Kinugasa, Oikawa, Onoda and Hirose2011) suggested that seed mass could only increase when N became more available at elevated CO2 concentrations. Legumes may use increased carbon (C) gain under elevated CO2 for increased nitrogen fixation (Allen & Boote Reference Allen, Boote, Reddy and Hodges2000), and can therefore increase seed mass without decreasing seed N. In non-legumes, seed mass increases may result in a decrease in seed N concentration. In some species, this decreased seed N may be at the expense of seed quality (Fenner Reference Fenner1991; Andalo et al. Reference Andalo, Godelle, Lefranc, Mousseau and Till-Bottraud1996).

Increasing temperature can negate the response to elevated CO2 (Prasad et al. Reference Prasad, Boote, Allen and Thomas2002) and may reduce seed mass (Spears et al. Reference Spears, Tekrony and Egli1997) because of the resulting acceleration in seed growth rate (dry matter accumulation) and reduction in the duration of seed filling (Weigand & Cueller Reference Weigand and Cueller1981; Young et al. Reference Young, Wilen and Bonham-Smith2004). However, a reduction in the rate of seed dry matter accumulation can also occur (Gibson & Paulsen Reference Gibson and Paulsen1999) and seed mass has also been reported not to change, or sometimes increase, in response to temperature increase (Peltonen-Sainio et al. Reference Peltonen-Sainio, Jauhiainen and Hakala2011). A reduced seed mass for a seed lot does not necessarily mean a loss in other seed quality attributes. Many studies have shown no relationship between seed mass and germination (Castro et al. Reference Castro, Hodar, Gomez and Basra2006) or seed mass and seed vigour (Powell Reference Powell1988).

GERMINATION

For high-quality seed lots, germination (defined as the process that begins with imbibition and which is completed by the production of a normal seedling; ISTA 2011) is desired by the seed industry to be as close to 100% as possible. The germination of a seed lot can be negatively affected by the conditions the seeds are exposed to during harvesting, drying, cleaning and storage, but can also be reduced by unfavourable environmental conditions in the field during seed growth and development (Dornbos Reference Dornbos and Basra1995), particularly temperature, rainfall and relative humidity (Egli et al. Reference Egli, Te Krony, Heitholt and Rupe2005).

Seed germination in response to elevated CO2 has been reported to decrease (Farnsworth & Bazazz Reference Farnsworth and Bazazz1995; Andalo et al. Reference Andalo, Godelle, Lefranc, Mousseau and Till-Bottraud1996; Quaderi & Reid Reference Quaderi and Reid2005), show no change (Huxman et al. Reference Huxman, Hamerlynck, Jordan, Salsman and Smith1998; Steinger et al. Reference Steinger, Gall and Schmid2000; Thomas et al. Reference Thomas, Prasad, Boote and Allen2009; Way et al. Reference Way, Ladeau, Mccarthy, Clark, Oren, Finzi and Jackson2010) or increase (Wulf & Alexander Reference Wulf and Alexander1985; Ziska & Bunce Reference Ziska and Bunce1993; Edwards et al. Reference Edwards, Clark and Newton2001). The responses vary among species (Ziska & Bunce Reference Ziska and Bunce1993) and genotypic variation has also been reported (Andalo et al. Reference Andalo, Godelle, Lefranc, Mousseau and Till-Bottraud1996).

Elevated CO2 has been shown to increase the C/N ratio in seeds (Huxman et al. Reference Huxman, Hamerlynck, Jordan, Salsman and Smith1998; Steinger et al. Reference Steinger, Gall and Schmid2000; He et al. Reference He, Flynn, Wolfe-Bellin, Fang and Bazzaz2005) and in non-legumes, seed N reduction can occur when seed mass is increased by elevated CO2 (see previous section). High seed N is an advantage for germination rate (Hara & Toriyama Reference Hara and Toriyama1998), but not germination per se. However, a change in C/N ratio can lead to a decrease in seed protein content, resulting in a reduction in the ability of the seed to supply the amino acids required for the de novo protein synthesis necessary for embryo growth in the germinating seed. This could reduce seed viability (Andalo et al. Reference Andalo, Godelle, Lefranc, Mousseau and Till-Bottraud1996).

Elevated CO2 also increases ethylene production (Esashi et al. Reference Esashi, Ooshima, Michihara, Kurota and Satoh1986) and Ziska & Bunce (Reference Ziska and Bunce1993) suggested that an increased availability of ethylene may have been the reason for the stimulated germination they reported. Ethylene is implicated in the promotion of germination of non-dormant seeds of many species (Leubner-Metzger Reference Leubner-Metzger and Basra2006).

In different plant species, sometimes even small differences in temperature during seed development and maturation can have an influence on germination (Gutterman Reference Gutterman and Fenner2000). High temperatures during seed filling frequently disrupt normal seed development, which increases the proportion of seeds that are shrivelled, abnormal and are of lower quality (Spears et al. Reference Spears, Tekrony and Egli1997). However, it has been shown that after removal of these seeds, the germination of the remaining seeds decreases as mean maximum temperature during seed filling increases (Khalil et al. Reference Khalil, Mexal and Murray2001, Reference Khalil, Mexal, Rehman, Khan, Wahab, Zubair, Khalil and Mohammad2010; Egli et al. Reference Egli, Te Krony, Heitholt and Rupe2005; Thomas et al. Reference Thomas, Prasad, Boote and Allen2009; Table 1). High-temperature stress before the developing seeds achieve physiological or mass maturity (PM – the end of the seed filling phase) is likely to inhibit the ability of the plant to supply the seeds with the assimilates necessary to synthesize the storage compounds required during the germination process (Dornbos & McDonald Reference Dornbos and McDonald1986), and/or the seeds suffer physiological damage (see McDonald & Nelson Reference McDonald and Nelson1986; Coolbear Reference Coolbear and Basra1995; Powell Reference Powell and Basra2006) to the extent that the ability to germinate is lost.

Table 1. Effect of temperature during seed development on seed germination and seed vigour of two soybean cultivars (adapted from Spears et al. Reference Spears, Tekrony and Egli1997)

* Day/night temperatures with 10 h at the day temperature; R5=beginning of seed fill; PM=physiological maturity; R8=harvest maturity.

† Soybean cultivars; McCall=indeterminate growth habit; Hutchenson=determinate growth habit.

‡ Seed vigour tests.

High-temperature stress after PM can also sometimes reduce germination (Green et al. Reference Green, Pinnell, Cavanaugh and Williams1965; Table 1), but more often reduces seed vigour (see next section).

The relationship between temperature during seed development and subsequent seed germination requires further investigation. For example in soybean, temperatures (32–38 °C) that reduced the germination of some cultivars in controlled environments did not vary during seed filling, in contrast to field temperatures which can vary substantially (Egli et al. Reference Egli, Te Krony, Heitholt and Rupe2005), and the plants were at these temperatures from anthesis until seed harvest. However, there may be critical periods during seed development when seeds are particularly sensitive to temperature (Egli et al. Reference Egli, Te Krony, Heitholt and Rupe2005; Shinohara et al. Reference Shinohara, Hampton and Hill2006a). This was investigated for pea (Pisum sativum L.) by Shinohara et al. (Reference Shinohara, Hampton and Hill2006a), who showed that when plants were exposed to a day/night temperature of 30/20 °C for 4 days (=240 °C h above a base temperature (Tb) of 25 °C) at the beginning of seed filling and then returned to the field until seed harvest, germination was significantly reduced in one of two cultivars (Table 2). Exposure to these conditions at later stages of seed development did not affect germination.

Table 2. Effect of high temperature (30/25 °C) for 4 days at different stages of seed development and maturation in two cultivars of pea (Pisum sativum L.) on seed quality components (adapted from Shinohara et al. Reference Shinohara, Hampton and Hill2006b)

* S1=beginning of seed filling (810 mg/g SMC); S2=rapid seed filling (700 mg/g SMC); S3=PM (630 mg/g SMC); S4=beginning of desiccation (440 mg/g SMC); S5=harvest maturity (230 mg/g SMC); SMCs are mean of the two cultivars.

† Data are the average of 25 results in the single seed conductivity vigour test.

‡ Pea cultivars.

s.e.d. (between cultivars)=10 (mean seed weight), 5·4 (germination), 0·041 (hollow heart) and 71 (average conductivity).

SEED VIGOUR

While the term germination has long been used to describe the planting value of a seed lot (ISTA 2011), when conditions in the seed bed are less than optimal the germination test is a poor predictor of field emergence (Dornbos Reference Dornbos and Basra1995), suggesting that a further physiological aspect to seed quality exists – seed vigour (Powell Reference Powell and Basra2006). Seed vigour is defined by ISTA (2011) as ‘the sum of those properties that determine the activity and level of performance of seed lots of acceptable germination in a wide range of environments’, or more simply, the ability of a high germination seed lot to emerge under seed-bed stress.

While there have been reports that elevated CO2 increases or decreases seedling vigour (i.e. growth rate or biomass production) because of the effect on seed mass (Huxman et al. Reference Huxman, Hamerlynck, Jordan, Salsman and Smith1998; Steinger et al. Reference Steinger, Gall and Schmid2000), there have been no reports on the effects of elevated CO2 on seed vigour.

Seed vigour is reduced by high-temperature stress before PM (Spears et al. Reference Spears, Tekrony and Egli1997; Egli et al. Reference Egli, Te Krony, Heitholt and Rupe2005; Shinohara et al. Reference Shinohara, Hampton and Hill2006a; Table 1) and after PM (TeKrony et al. Reference TeKrony, Egli, Balles, Pfeiffer and Fellows1979, Reference TeKrony, Egli, Balles and Hebblethwaite1980; Gibson & Mullen Reference Gibson and Mullen1996; Hampton Reference Hampton, McManus, Outred and Pollock2000). Shinohara et al. (Reference Shinohara, Hampton, Hill, Juntakool, Suprakarn and Sagwansupyakorn2008) examined the relationship between vigour test results for 262 garden pea seeds lots produced in New Zealand and climate data in five regions over four consecutive production seasons, and while regional and seasonal variation for vigour occurred, these variations were significantly associated with temperature during seed development – generally the higher the temperature, the lower the seed vigour.

The susceptibility of seeds to loss of vigour following high-temperature stress depends on the stage of development (Shinohara et al. Reference Shinohara, Hampton and Hill2006a). Using hollow heart, a physiological disorder of germinating pea seeds (Halligan Reference Halligan1986) as a seed vigour indicator (Castillo et al. Reference Castillo, Hampton and Coolbear1993), Shinohara et al. (Reference Shinohara, Hampton and Hill2006a) found in a field study that hourly thermal time (HTT, measured in degree hours, °Ch, Tb=25 °C) when seeds were at the green-wrinkled pod stage (700–800 mg/g seed moisture content (SMC)) was significantly correlated with hollow heart incidence at harvest, and that 100 °Ch were required to induce the condition. There was no such relationship between HTT and hollow heart after PM. While there were cultivar differences, for one cultivar there was a linear increase in hollow heart incidence as the degree hours (°Ch) increased. In a follow-up controlled environment study, Shinohara et al. (Reference Shinohara, Hampton and Hill2006b) confirmed this result, by demonstrating that exposure to day/night temperatures of 30 and 25 °C, respectively, for 4 days (240 °Ch, Tb=25 °C) at the green-wrinkled pod stage induced hollow heart, but exposure to the same conditions at the beginning of seed fill (>800 mg/g SMC), PM (550–650 mg/g SMC) or after PM did not (Table 2). Single-seed conductivity (which is an indicator of cell membrane integrity – see Powell Reference Powell and Basra2006) was increased only after exposure of the developing seeds to the high temperature at or after PM, and not before (Table 1).

Seed vigour loss is associated with seed physiological deterioration (Powell Reference Powell1988; Hampton & Coolbear Reference Hampton and Coolbear1990), and lipid peroxidation is the most frequently cited cause (McDonald Reference McDonald1999). Lipid peroxidation causes cellular degeneration through free radical assault on important cellular molecules and structures (Wilson & McDonald Reference Wilson and McDonald1986). McDonald (Reference McDonald1999), in his model of seed deterioration, proposed four types of cell damage, viz. mitochondrial dysfunction, enzyme inactivation, membrane degradation and genetic damage.

Grass & Burris (Reference Grass and Burris1995) reported that high-temperature stress of the parent plant caused mitochondrial degeneration and reduced adenosine triphosphate (ATP) accumulation, energy levels and rates of oxygen uptake in imbibing wheat embryos (Table 3), providing clear evidence for metabolic changes at the mitochondrial level in early seed germination in response to heat stress during seed development and maturation. High temperatures during reproductive growth increase seed cell membrane damage (Nilsen & Orcutt Reference Nilsen, Orcutt, Nilsen and Orcutt1996; Shinohara et al. Reference Shinohara, Hampton and Hill2006b) so that electrolyte leakage from seeds is increased (Castillo et al. Reference Castillo, Hampton and Coolbear1994; Spears et al. Reference Spears, Tekrony and Egli1997; Shinohara et al. Reference Shinohara, Hampton and Hill2006b). High leachate conductivity in pea has been associated with dead/deteriorating tissue on the abaxial surface of the cotyledons (Powell Reference Powell, Hebblethwaite, Heath and Dawkins1985; Shinohara et al. Reference Shinohara, Hampton and Hill2006b), and on the adaxial cotyledonary surface for hollow heart (Don et al. Reference Don, Bustamante, Rennie and Seddon1984; Shinohara et al. Reference Shinohara, Hampton and Hill2006b). However, temperature stress also results in damage to the shoot apical meristem of the embryonic axis (Fu et al. Reference Fu, Lu, Chen, Zhang, Liu, Li and Cai1988; Senaratna et al. Reference Senaratna, Gusse and McKersie1988). Membrane disorganization would reduce mitochondrial efficiency and may allow the release of peroxidative enzymes capable of causing subsequent cellular damage after imbibition has begun (McDonald Reference McDonald1999).

Table 3. Effect of temperature during seed development and maturation on nucleotide content, mitochondrial respiration rate and adenylate energy charge (AEC) of excised wheat embryos after 4 h imbibition (adapted from Grass & Burris Reference Grass and Burris1995)

* Day/night with 8 h day temperature and 16 h night temperature.

† AMP, adenosine monophosphate; ADP, adenosine diphosphate; ATP, adenosine triphosphate.

‡ AEC expressed as the ratio (ATP+0·5ADP/ATP+ADP+AMP)=energy status of the seed (Atkinson Reference Atkinson1968).

If heat stress leads to mitochondrial dysfunction and membrane damage, it may also result in reduced enzyme activity (e.g. decreased α-amylase – Shephard et al. Reference Shephard, Naylor and Stuchbury1996) and genetic damage (e.g. decreased DNA synthesis – Cruz-Garcia et al. Reference Cruz-Garcia, Gonzalez-Hernandez, Molina-Moreno and Vazquez-Ramos1995). Whether these and other seed deteriorative changes (see McDonald Reference McDonald1999) occur following heat stress during seed development and maturation is yet to be determined.

CONCLUSIONS

The environment during seed development and maturation can significantly reduce seed quality (Dornbos Reference Dornbos and Basra1995; Gusta et al. Reference Gusta, Johnson, Nesbitt and Kirkland2004; Egli et al. Reference Egli, Te Krony, Heitholt and Rupe2005; Shinohara et al. Reference Shinohara, Hampton, Hill, Juntakool, Suprakarn and Sagwansupyakorn2008), particularly seed vigour. How likely is it that elevated CO2 levels and temperature increases of up to 3 °C by 2050 will further increase this loss of seed quality? To answer this question accurately will require substantially more research in order to determine the critical periods during seed development when seeds are sensitive to environmental stresses, and for temperature, how this interacts with the duration of exposure to elevated temperatures which are deleterious to seed quality. For example, Shinohara et al. (Reference Shinohara, Hampton and Hill2006b) found that during the rapid seed filling stage in pea, a temperature of 30/25 °C for 2 days (120 °Ch at Tb=25 °C) did not induce hollow heart, but 4 days induced hollow heart in one cultivar (see Table 2), and 6 days (360 °Ch) induced the condition in both cultivars used (0·43 in cvar Alderman and 0·23 in cvar Early Onward).

From the information that is available, it can be concluded that predicted environmental changes will lead to the increased occurrence of loss of seed quality, particularly seed vigour and possibly germination. While seed mass will also change, this does not necessarily imply any negative effect on germination or vigour. To minimize the risk of reductions in seed quality the seed industry will therefore have to consider:

  1. (a) Moving seed production to the limits of adaptation either in latitude (northern or southern) or in elevation (highland and mountainous regions) in order to reduce the chances of environmental stress (Egli et al. Reference Egli, Te Krony, Heitholt and Rupe2005; Shinohara et al. Reference Shinohara, Hampton, Hill, Juntakool, Suprakarn and Sagwansupyakorn2008).

  2. (b) Changing sowing date so that seed filling occurs at lower temperatures (Castillo et al. Reference Castillo, Hampton and Coolbear1994; Egli et al. Reference Egli, Te Krony, Heitholt and Rupe2005; Shinohara et al. Reference Shinohara, Hampton and Hill2006a). The latter authors demonstrated that for the pea cultivar Alderman, HTT (Tb=25 °C) during the rapid seed filling stage was 198, 106 and 21 °Ch for sowings at the same site in September, October and November, respectively, and the number of hours during this stage when temperature exceeded 25 or 30 °C also reduced as sowing date was delayed (Table 4).

  3. (c) Exploring genotypic differences in the ability to acquire and retain good seed quality in stressful environments, firstly among existing cultivars (Spears et al. Reference Spears, Tekrony and Egli1997; Shinohara et al. Reference Shinohara, Hampton and Hill2006a), and in the breeding of new cultivars (Ainsworth et al. Reference Ainsworth, Beier, Calfapietra, Ceulemans, Durand-Tardif, Farquhar, Godbold, Hendrey, Hickler, Kaduk, Karnosky, Kimball, Körner, Koornneef, Lafarge, Leakey, Lewin, Long, Manderscheid, McNeil, Mies, Miglietta, Morgan, Nagy, Norby, Norton, Percy, Rogers, Soussana, Stitt, Weigel and White2008b).

Table 4. Effect of sowing date at the same field site on HTT (Tb=25 °C) and the number of hours of exposure to temperature exceeding 25 and 30 °C during the period when SMC was between 700 and 800 mg/g for garden pea cvar Alderman (adapted from Shinohara et al. Reference Shinohara, Hampton and Hill2006a).

* Dates when seeds were adjudged to have reached PM.

† Period when SMC was between 700 and 800 mg/g.

References

REFERENCES

Ainsworth, E. A., Rogers, A. & Leakey, A. D. B. (2008 a). Targets for crop biotechnology in a future high-CO2 and high-O3 world. Plant Physiology 147, 13–19.CrossRefGoogle Scholar
Ainsworth, E. A., Beier, C., Calfapietra, C., Ceulemans, R., Durand-Tardif, M., Farquhar, G. D., Godbold, D. L., Hendrey, G. R., Hickler, T., Kaduk, J., Karnosky, D. F., Kimball, B. A., Körner, C., Koornneef, M., Lafarge, T., Leakey, A. D., Lewin, K. F., Long, S. P., Manderscheid, R., McNeil, D. L., Mies, T. A., Miglietta, F., Morgan, J. A., Nagy, J., Norby, R. J., Norton, R. M., Percy, K. E., Rogers, A., Soussana, J. F., Stitt, M., Weigel, H. J. & White, J. W. (2008 b). Next generation of elevated CO2 experiments with crops: a critical investment for feeding the future world. Plant, Cell and Environment 31, 1317–1324.CrossRefGoogle ScholarPubMed
Almekinders, C. J. M. & Louwaars, N. P. (1999). Farmer's Seed Production. New Approaches and Practices. London: ITDG Publishing.CrossRefGoogle Scholar
Andalo, C., Godelle, B., Lefranc, M., Mousseau, M. & Till-Bottraud, I. (1996). Elevated CO2 decreases seed germination in Arabidopsis thaliana. Global Change Biology 2, 129–135.CrossRefGoogle Scholar
Allen, L. H. Jr & Boote, K. J. (2000). Crop ecosystem responses to climatic change: soybean. In Climate Change and Global Crop Productivity (Eds Reddy, K. R. & Hodges, H. F.), pp. 133–160. Wallingford, UK: CAB International.CrossRefGoogle Scholar
Atkinson, D. E. (1968). The energy charge of the adenylate pool as a regulatory parameter. Biochemistry 7, 4030–4034.CrossRefGoogle Scholar
Baker, J. T., Allen, L. H. Jr, Boote, K. J., Jones, P. & Jones, J. W. (1989). Response of soybean to air temperature and carbon dioxide concentration. Crop Science 29, 98–105.CrossRefGoogle Scholar
Bruins, M. (2009). The evolution and contribution of plant breeding to global agriculture. In Proceedings of the Second World Seed Conference: Responding to the Challenges of a Changing World: The Role of New Plant Varieties and High Quality Seed in Agriculture, pp. 18–31. Rome: FAO.Google Scholar
Castillo, A. G., Hampton, J. G. & Coolbear, P. (1993). Effect of population density on within canopy environment and seed vigour in garden pea (Pisum sativum L.). Proceedings of the Annual Conference of the Agronomy Society of New Zealand 23, 99–106.Google Scholar
Castillo, A. G., Hampton, J. G. & Coolbear, P. (1994). Effect of sowing date and harvest timing on seed vigour in garden pea (Pisum sativum L.). New Zealand Journal of Crop and Horticultural Science 22, 91–95.CrossRefGoogle Scholar
Castro, J., Hodar, J. A. & Gomez, J. M. (2006). Seed size. In Handbook of Seed Science and Technology (Ed. Basra, A. S.), pp. 397–427. New York: Food Products Press.Google Scholar
Ceccarelli, S., Grando, S., Maatougui, M., Michael, M., Slash, M., Haghparast, R., Rahmanian, M., Taheri, A., Al-Yassin, A., Benbelkacem, A., Labdi, M., Mimoun, H. & Nachit, M. (2010). Plant breeding and climate changes. Journal of Agricultural Science, Cambridge 148, 627–637.CrossRefGoogle Scholar
Coolbear, P. (1995). Mechanisms of seed deterioration. In Seed Quality: Basic Mechanisms and Agricultural Implications (Ed. Basra, A. S.), pp. 223–277. New York: Food Products Press.Google Scholar
Cruz-Garcia, F., Gonzalez-Hernandez, V. A., Molina-Moreno, J. & Vazquez-Ramos, J. M. (1995). Seed deterioration and respiration as related to DNA metabolism in germinating maize. Seed Science and Technology 23, 477–486.Google Scholar
Dijkstra, P., Schapendonk, H. M. C., Groenwold, K., Jansen, M. & van de Geijn, S. C. (1999). Seasonal changes in the response of winter wheat to elevated atmospheric CO2 concentration grown in open-top chambers and field tracking enclosures. Global Change Biology 5, 563–576.CrossRefGoogle Scholar
Don, R., Bustamante, L., Rennie, W. J. & Seddon, M. G. (1984). Hollow heart in pea (Pisum sativum L.). Seed Science and Technology 12, 707–721.Google Scholar
Dornbos, D. L. Jr (1995). Production environment and seed quality. In Seed Quality: Basic Mechanisms and Agricultural Implications (Ed. Basra, A. S.), pp. 119–152. New York: Food Products Press.Google Scholar
Dornbos, D. L. Jr & McDonald, M. B. (1986). Mass and composition of developing soybean seeds at five reproductive growth stages. Crop Science 26, 624–630.CrossRefGoogle Scholar
Edwards, G. R., Clark, H. & Newton, P. C. D. (2001). The effects of elevated CO2 on seed production and seedling recruitment in a sheep-grazed pasture. Oecologia 127, 383–394.CrossRefGoogle Scholar
Egli, D. B., Te Krony, D. M., Heitholt, J. J. & Rupe, J. (2005). Air temperature during seed filling and soybean seed germination and vigour. Crop Science 45, 1329–1335.CrossRefGoogle Scholar
Esashi, Y., Ooshima, Y., Michihara, Aabe M., Kurota, A. & Satoh, S. (1986). CO2-enhanced C2H4 production in tissues of imbibed cocklebur seeds. Australian Journal of Plant Physiology 13, 417–429.Google Scholar
Farnsworth, E. J. & Bazazz, F. A. (1995). Inter- and intra-generic differences in growth, reproduction, and fitness of nine herbaceous annual species grown in elevated CO2 environments. Oecologia 104, 454–466.CrossRefGoogle Scholar
Fenner, M. (1991). The effects of the parent environment on seed germinability. Seed Science Research 1, 75–84.CrossRefGoogle Scholar
Fu, J. R., Lu, X. H., Chen, R. Z., Zhang, B. Z., Liu, Z. S., Li, Z. S. & Cai, C. Y. (1988). Osmoconditioning of peanut (Arachis hypogaea L.) seeds with PEG to improve vigour and some biochemical activities. Seed Science and Technology 16, 197–212.Google Scholar
Gibson, L. R. & Mullen, R. E. (1996). Soybean seed quality reductions by high day and night temperature. Crop Science 36, 1615–1619.CrossRefGoogle Scholar
Gibson, L. R. & Paulsen, G. M. (1999). Yield components of wheat grown under high temperature stress during reproductive growth. Crop Science 39, 1841–1846.CrossRefGoogle Scholar
Gornall, J., Betts, R., Burke, E., Clark, R., Camp, J., Willett, K. & Wiltshire, A. (2010). Implications of climate change for agricultural productivity in the early twenty-first century. Philosophical Transactions of the Royal Society B: Biological Sciences 365, 2973–2989.CrossRefGoogle ScholarPubMed
Grass, L. & Burris, J. S. (1995). Effect of heat stress during seed development and maturation on wheat (Triticum durum) seed quality. II. Mitochondrial respiration and nucleotide pools during early germination. Canadian Journal of Plant Science 75, 831–839.CrossRefGoogle Scholar
Green, D. E., Pinnell, E. L., Cavanaugh, L. E. & Williams, L. F. (1965). Effect of planting date and maturity date on soybean seed quality. Agronomy Journal 57, 165–168.CrossRefGoogle Scholar
Gusta, L. V., Johnson, E. N., Nesbitt, N. T. & Kirkland, K. J. (2004). Effect of seeding date on canola seed quality and seed vigour. Canadian Journal of Plant Science 84, 463–471.CrossRefGoogle Scholar
Gutterman, Y. (2000). Maternal effects on seed during development. In Seeds: The Ecology of Regeneration in Plant Communities (Ed. Fenner, M.), pp. 59–84. Wallingford, UK: CAB International.CrossRefGoogle Scholar
Halligan, E. A. (1986). The effect of elevated temperatures and their duration on the incidence of hollow heart in pea seeds. Annals of Applied Biology 109, 619–625.CrossRefGoogle Scholar
Hampton, J. G. (2000). Producing quality seed: the problem of seed vigour. In Current Research on Seeds in New Zealand (Eds McManus, M. T., Outred, H. A. & Pollock, K. M.), pp. 53–67. Agronomy Society of New Zealand Special Publication No. 12. Christchurch, New Zealand: Agronomy Society of New Zealand.Google Scholar
Hampton, J. G. (2002). What is seed quality? Seed Science and Technology 30, 1–10.Google Scholar
Hampton, J. G. & Coolbear, P. (1990). Potential versus actual seed performance – can vigour testing provide an answer? Seed Science and Technology 18, 215–228.Google Scholar
Hara, Y. & Toriyama, K. (1998). Seed nitrogen accelerates the rates of germination, emergence and establishment of rice plants. Soil Science and Plant Nutrition 44, 359–366.CrossRefGoogle Scholar
He, J. S., Flynn, D. F. B., Wolfe-Bellin, K., Fang, J. & Bazzaz, F. A. (2005). CO2 and nitrogen, but not population density, alter the size and C/N ratio of Phytolacca americana seeds. Functional Ecology 19, 437–444.CrossRefGoogle Scholar
Hikosaka, K., Kinugasa, T., Oikawa, S., Onoda, Y. & Hirose, T. (2011). Effects of elevated CO2 concentration on seed production in C3 annual plants. Journal of Experimental Botany 62, 1523–1530.CrossRefGoogle ScholarPubMed
Houghton, J. T., Ding, Y., Griggs, D. J., Noguer, M., Van Der Linden, P. J., Dai, X., Maskell, K. & Johnson, C. A. (2001). Climate Change 2001: The Scientific Basis. Report of the IPCC. Cambridge, UK: Cambridge University Press.Google Scholar
Huxman, T. E., Hamerlynck, E. P., Jordan, D. N., Salsman, K. A. & Smith, S. D. (1998). The effects of parental CO2 environment on seed quality and subsequent seedling performance in Bromus rubens. Oecologia 114, 207–208.CrossRefGoogle Scholar
ISTA (2011). International Rules for Seed Testing. Bassersdorf, Switzerland: International Seed Testing Association.Google Scholar
Jablonski, L. M., Wang, X. & Curtis, P. S. (2002). Plant reproduction under elevated CO2 conditions: a meta-analysis of reports. New Phytologist 156, 9–26.CrossRefGoogle Scholar
Jaggard, K. W., Qi, A. & Ober, E. S. (2010). Possible changes to arable crop yields by 2050. Philosophical Transactions of the Royal Society B: Biological Sciences 365, 2835–2851.CrossRefGoogle ScholarPubMed
Khalil, S. K., Mexal, J. G. & Murray, L. W. (2001). Soybean seed matured on different dates affect seed quality. Pakistan Journal of Biological Sciences 4, 365–370.CrossRefGoogle Scholar
Khalil, S. K., Mexal, J. G., Rehman, A., Khan, A. Z., Wahab, S., Zubair, M., Khalil, I. H. & Mohammad, F. (2010). Soybean mother plant exposure to temperature stress and its effect on germination under osmotic stress. Pakistan Journal of Botany 42, 213–225.Google Scholar
Leubner-Metzger, G. (2006). Hormonal interactions during seed dormancy release and germination. In Handbook of Seed Science and Technology (Ed. Basra, A. S.), pp. 303–342. New York: Food Products Press.Google Scholar
McDonald, M. B. (1999). Seed deterioration: physiology, repair and assessment. Seed Science and Technology 27, 177–237.Google Scholar
McDonald, M. B. & Nelson, C. J. (1986). Physiology of Seed Deterioration. Special Publication No. 11, Madison, WI, USA: Crop Science Society of America.CrossRefGoogle Scholar
Miyagi, K. M., Kinugasa, T., Hikosaka, K. & Hirose, T. (2007). Elevated CO2 concentration, nitrogen use, and seed production in annual plants. Global Change Biology 13, 2161–2170.CrossRefGoogle Scholar
Musgrave, M. E., Strain, B. R. & Siedow, J. N. (1986). Response of two pea hybrids to CO2 enrichment: a test of the energy overflow hypothesis for alternative respiration. Proceedings of the National Academy of Sciences, USA 83, 8157–8161.CrossRefGoogle ScholarPubMed
Nilsen, E. T. & Orcutt, D. M. (1996). Plant membranes as environmental sensors. In The Physiology of Plants Under Stress:Abiotic Factors (Eds Nilsen, E. T. & Orcutt, D. M.), pp. 50–82. New York: John Wiley and Sons.Google Scholar
Peltonen-Sainio, P., Jauhiainen, L. & Hakala, K. (2011). Crop responses to temperature and precipitation according to long-term multi-location trials at high-latitude conditions. Journal of Agricultural Science, Cambridge 149, 49–62.CrossRefGoogle Scholar
Powell, A. A. (1985). Impaired membrane integrity: a fundamental cause of seed quality differences in peas. In The Pea Crop: a Basis for Improvement (Eds Hebblethwaite, P. D., Heath, M. C. & Dawkins, T. C. K.), pp. 383–394. London: Butterworths.CrossRefGoogle Scholar
Powell, A. A. (1988). Seed vigour and field establishment. Advances in Research and Technology of Seeds 11, 29–61.Google Scholar
Powell, A. A. (2006). Seed vigour and its assessment. In Handbook of Seed Science and Technology (Ed. Basra, A. S.), pp. 603–648. New York: Food Products Press.Google Scholar
Prasad, P. V. V., Boote, K. J., Allen, L. H. Jr & Thomas, J. M. G. (2002). Effects of elevated temperature and carbon dioxide on seed-set and yield of kidney bean (Phaseolus vulgaris L.). Global Change Biology 8, 710–721.CrossRefGoogle Scholar
Quaderi, M. M. & Reid, D. M. (2005). Growth and physiological responses of canola (Brassica napus) to UV-B and CO2 under controlled environment conditions. Physiologia Plantarum 125, 247–259.CrossRefGoogle Scholar
Senaratna, T., Gusse, J. F. & McKersie, B. D. (1988). Age-induced changes in cellular membranes of imbibed soybean axes. Physiologia Plantarum 73, 85–91.CrossRefGoogle Scholar
Shephard, H. L., Naylor, R. E. L. & Stuchbury, T. (1996). The influence of seed maturity at harvest and drying method on the embryo, α-amylase activity and seed vigour in sorghum (Sorghum bicolor (L.) Moench). Seed Science and Technology 24, 245–249.Google Scholar
Shinohara, T., Hampton, J. G. & Hill, M. J. (2006 a). Effects of the field environment before and after seed physiological maturity on hollow heart occurrence in garden pea (Pisum sativum). New Zealand Journal of Crop and Horticultural Science 34, 247–255.CrossRefGoogle Scholar
Shinohara, T., Hampton, J. G. & Hill, M. J. (2006 b). Location of deterioration within garden pea (Pisum sativum) cotyledons is associated with the timing of exposure to high temperature. New Zealand Journal of Crop and Horticultural Science 34, 299–309.CrossRefGoogle Scholar
Shinohara, T., Hampton, J. G., Hill, M. J., Juntakool, S., Suprakarn, S. & Sagwansupyakorn, C. (2008). Variations in pea (Pisum sativum L.) seed vigour among regions of production and cropping seasons are associated with temperature during reproductive growth. Journal of the Japanese Society of Agricultural Technology Management 14, 148–155.Google Scholar
Smith, S. D., Huxman, T. E., Zitzer, S. F., Charlet, T. N., Housman, D. C., Coleman, J. S., Fenstermaker, L. K., Seemann, J. R. & Nowak, R. W. (2000). Elevated CO2 increases productivity and invasive species success in an arid ecosystem. Nature 408, 79–82.CrossRefGoogle Scholar
Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M. & Miller, H. L. (2007). Technical summary. In Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Annual Report of the Intergovernmental Panel on Climate Change (Eds Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M. & Miller, H. L.), pp. 19–840. Cambridge, UK: Cambridge University Press.Google Scholar
Spears, J. F., Tekrony, D. M. & Egli, D. B. (1997). Temperature during seed filling and soybean seed germination and vigour. Seed Science and Technology 25, 233–244.Google Scholar
Steinger, T., Gall, R. & Schmid, B. (2000). Maternal and direct effects of elevated CO2 on seed provisioning, germination and seedling growth in Bromus erectus. Oecologia 123, 475–480.CrossRefGoogle ScholarPubMed
TeKrony, D. M., Egli, D. B., Balles, J., Pfeiffer, T. & Fellows, R. J. (1979). Physiological maturity in soybeans. Agronomy Journal 71, 771–775.CrossRefGoogle Scholar
TeKrony, D. M., Egli, D. B. & Balles, J. (1980). The effects of the field production environment on soybean seed quality. In Seed Production (Ed. Hebblethwaite, P. D.), pp. 403–426. London: Butterworth and Co Ltd.Google Scholar
Thomas, J. M. G., Prasad, P. V. V., Boote, K. J. & Allen, L. H. (2009). Seed composition, seedling emergence and early seedling vigour of red kidney bean seed produced at elevated temperature and carbon dioxide. Journal of Agronomy and Crop Science 195, 148–156.CrossRefGoogle Scholar
Wagner, J., Luscher, A., Hillebrand, C., Kobald, B., Spitaler, N. & Larcher, W. (2001). Sexual reproduction of Lolium perenne L. and Trifolium repens L. under free air CO2 enrichment (FACE) at two levels of nitrogen application. Plant, Cell and Environment 24, 957–965.CrossRefGoogle Scholar
Way, D. A., Ladeau, S. L., Mccarthy, H. R., Clark, J. S., Oren, R., Finzi, A. C. & Jackson, R. B. (2010). Greater seed production in elevated CO2 is not accompanied by reduced seed quality in Pinus taeda L. Global Change Biology 16, 1046–1056.CrossRefGoogle Scholar
Weigand, C. L. & Cueller, J. A. (1981). Duration of grain filling and kernel weight of wheat as affected by temperature. Crop Science 21, 95–101.CrossRefGoogle Scholar
Wheeler, T. R., Craufurd, P. Q., Ellis, R. H., Porter, J. R. & Prasad, P. V. V. (2000). Temperature variability and the yield of annual crops. Agriculture, Ecosystems and Environment 82, 159–167.CrossRefGoogle Scholar
Wilson, D. O. & McDonald, M. B. (1986). The lipid peroxidation model of seed deterioration. Seed Science and Technology 14, 269–300.Google Scholar
Wulf, R. D. & Alexander, H. M. (1985). Intraspecific variation in the response to CO2 enrichment in seeds and seedlings of Plantago lanceolata. Oecologia 66, 458–460.CrossRefGoogle Scholar
Young, L. W., Wilen, R. W. & Bonham-Smith, P. C. (2004). High temperature stress of Brassica napus during flowering reduces micro-and megagametophyte fertility, induces fruit abortion, and disrupts seed production. Journal of Experimental Botany 55, 485–495.CrossRefGoogle ScholarPubMed
Ziska, L. H. & Bunce, J. A. (1993). The influence of elevated CO2 and temperature on seed germination and emergence from soil. Field Crops Research 34, 147–157.CrossRefGoogle Scholar
Figure 0

Table 1. Effect of temperature during seed development on seed germination and seed vigour of two soybean cultivars (adapted from Spears et al. 1997)

Figure 1

Table 2. Effect of high temperature (30/25 °C) for 4 days at different stages of seed development and maturation in two cultivars of pea (Pisum sativum L.) on seed quality components (adapted from Shinohara et al. 2006b)

Figure 2

Table 3. Effect of temperature during seed development and maturation on nucleotide content, mitochondrial respiration rate and adenylate energy charge (AEC) of excised wheat embryos after 4 h imbibition (adapted from Grass & Burris 1995)

Figure 3

Table 4. Effect of sowing date at the same field site on HTT (Tb=25 °C) and the number of hours of exposure to temperature exceeding 25 and 30 °C during the period when SMC was between 700 and 800 mg/g for garden pea cvar Alderman (adapted from Shinohara et al. 2006a).