Breeding for drought tolerance using novel genetic resources possessing relevant agronomic and adaptive traits is a key to enhance productivity and food security in wheat growing areas. Herein, the main objectives were (i) to use a combination scoring index (multiple scoring index, (MSI)) for selection of durum wheat genotypes under different drought stress intensities (SIs) (ii) to examine repeatability of the scoring index through bootstrap re-sample method, and (iii) to study the relationship of MSI with some drought-adaptive traits. Sixteen durum wheat genotypes were grown under rainfed and irrigated conditions during three cropping seasons (2012–2015), resulting in different drought SIs, that is, mild (SI < 0.3), moderate (0.3 < SI < 0.6), and severe (SI > 0.6). The average grain yields among test environments varied between 708 and 3631 kg ha−1. The validation of the methodology of scoring index was confirmed by the correlation coefficients between score indices and their original values across different drought SIs. According to MSI, the genotypes G16, G1, and G3 had the best combination of high productivity and high resilience to mild, moderate, and severe drought stress conditions, respectively. These results indicated that the ranking of genotypes varied among different drought SIs, which support the high potential of durum wheat for adaptation to different drought stress conditions. Based on the bootstrap samples, non-repeatable correlations were observed between the estimates of MSI from different levels of stress. The significant correlation between MSI with grain yield and 1000-kernel weight (TKW) under severe drought condition provides evidence that MSI ultimately be considered as a tool for effective selection of drought-tolerant genotypes. The MSI selected genotypes based on high productivity and resilience, to each level of drought SI, and favorable adaptive traits useful for breeding.

Understanding the genetic variability, heritability and genetic advance (GA) of traits in any plant population is an important pre-requisite for variety development. The objectives of the study were to assess the level of genetic variability among vegetative growth traits and yield, assess the relationship among the growth traits and yield and predict GA for the most heritable traits among Robusta coffee full-sib families. The trial was established in June 2009 at the experimental fields of the Cocoa Research Institute of Ghana with 62 full-sib families planted in a randomized complete block design with six replications. Significant (p < 0.05) variation was observed among the full-sib families evaluated for all traits, except for span (canopy diameter). Span and number of laterals were genetically correlated (p < 0.001) with cumulative yield (2013–2017), with span being the vegetative growth trait most strongly related to cumulative yield (rg = 0.60, p < 0.001). The most heritable vegetative growth and yield traits were, respectively, number of laterals (H2 = 0.59) and cumulative yield (H2 = 0.41). The top 10 families (BP40, BP41, BP9, BP36, BP34, BP28, BP37, BP14, BP4 and BP10) in terms of cumulative yield are proposed for multi-location evaluation and possible release as hybrids for coffee farmers in Ghana.

On low-input smallholder farms of Kenyan upland landscapes, erosion of nutrient-rich topsoil strongly affects crop yields. Where maize (Zea mays) is intercropped on erosion-prone slopes, intercropping can potentially reduce soil erosion. The objective of this research was to quantify the contribution of crops and crop mixtures of different growth habits to erosion control and their influence on above-ground biomass and earthworm abundance as indicators of soil function in smallholder farming systems under a bimodal rainfall pattern in Western Kenya. The experiment involved five treatments, namely maize (Z. mays)/common bean (Phaseolus vulgaris) intercrop (maize intercrop), maize/common bean intercrop plus Calliandra (Calliandra calothyrsus) hedgerows and Calliandra mulch (Calliandra), sole Lablab (Lablab purpureus), sole Mucuna (Mucuna pruriens) and groundnut (Arachis hypogaea) intercropped with maize (during the short rains). The experiment was conducted over three consecutive cropping seasons and the cropping system had significant effects on soil loss, runoff, water infiltration, earthworm abundance and above-ground biomass and crop grain yield. The Calliandra treatment had the lowest runoff (11.6–17.2 mm ha−1) and soil erosion (31–446 kg ha−1 per season) in all the seasons, followed by the Mucuna treatment. Lablab was affected by disease and showed the highest soil erosion in the last two seasons. Infiltration was highest in Calliandra treatment, and earthworm abundance was higher under Mucuna and Calliandra treatments (229 and 165 earthworms per square metre, respectively) than under other crops. Our results suggest that including sole crops of herbaceous species such as Mucuna, or tree hedgerows with mixtures of maize and grain legumes has the potential to reduce runoff and soil erosion in smallholder farming. Additionally, these species provide a suitable habitat for earthworms which stabilise soil structure and macropores and thus potentially increase infiltration, further reducing soil erosion.

Parthenium hysterophorus is a prolific invasive weed species, which infests many crops in over 40 countries around the world. A 2-year field study was carried out to quantify the potential impacts of this weed on direct-seeded rice. Parthenium weed was allowed to compete for 2, 4, 6 or 8 weeks after crop emergence, while full season weedy and weed-free plots were maintained as controls. Parthenium weed plants grew taller and attained more biomass as the competition duration prolonged. The yield and yield-related attributes of rice were negatively affected with increasing competition duration. The season-long competition caused the highest reductions in panicle number (28–34%), panicle length (26–27%), grains per panicle (22–23%) and grain yield (33 and 38%) of rice in both years. Weed competition for 2–8 weeks caused 5–34% and 6–33% losses in rice grain yield during both years, respectively. Importantly, Parthenium weed control after 8 weeks of competition did not improve rice yield significantly. The results suggested that Parthenium weed should be controlled in rice fields between 4 and 8 weeks after crop emergence under direct-seeded conditions to avoid over 10% yield losses.

Rice is widely grown in rainfed lowlands during the wet season in the Mekong region. Limited nutrient availability is a common constraint on crop yield, and the optimal rate of fertilizer application depends on the soil type. The objective of our study was to evaluate rice productivity and the economic feasibility of various nutrient management regimes in Cambodia. We conducted field experiments on three soil types (Prey Khmer, Prateah Lang, and Toul Samroung, equivalent to Psamments, Plinthustalfs, and Endoaqualfs, respectively) in four provinces (Battambang, Kampong Thom, Pursat, and Siem Reap) during the 2016 and 2017 wet seasons to compare nine (2016) and seven (2017) N–P–K combinations. Grain yield ranged from 0.9 to 4.8 t ha−1 in 2016 and from 1.0 to 5.2 t ha−1 in 2017, depending on soil type and nutrient management. The Prey Khmer soil contained around 80% sand, and rice yield responded most weakly to nutrient management. The moderate fertilizer input in the current soil-specific recommendation was effective on this soil type. However, on more fertile soils with a higher clay content and a higher cation-exchange capacity (Toul Samroung and Prateah Lang), an additional 20 kg N ha−1 combined with adding 15 kg ha−1 of P2O5 or 20 kg ha−1 of K2O significantly increased yield and economic return. Although P and K use during Cambodia’s wet season is uncommon, our results demonstrate the importance of these nutrients in improving the country’s rice production.

High-yielding short-duration cultivars are required due to the development of mechanized large-scale double-season rice (i.e. early- and late-season rice) production in China. The objective of this study was to identify whether existing early-season rice cultivars can be used as resources to select high-yielding, short-duration (less than 115 days) cultivars of machine-transplanted late-season rice. Field experiments were conducted in Yongan, Hunan Province, China in the early and late rice-growing seasons in 2015 and 2016. Eight early-season rice cultivars (Liangyou 6, Lingliangyou 211, Lingliangyou 268, Xiangzaoxian 32, Xiangzaoxian 42, Zhongjiazao 17, Zhongzao 39, and Zhuliangyou 819) with growth durations of less than 115 days were used in 2015, and four cultivars (Lingliangyou 268, Zhongjiazao 17, Zhongzao 39, and Zhuliangyou 819) with good yield performance in the late season in 2015 were grown in 2016. All cultivars had a growth duration of less than 110 days when grown in the late season in both years. Zhongjiazao 17 produced the maximum grain yield of 9.61 Mg ha−1 with a daily grain yield of 108 kg ha−1 d−1 in the late season in 2015. Averaged across both years, Lingliangyou 268 had the highest grain yield of 8.57 Mg ha−1 with a daily grain yield of 95 kg ha−1 d−1 in the late season. The good yield performance of the early-season rice cultivars grown in the late season was mainly attributable to higher apparent radiation use efficiency. Growth duration and grain yield of early-season rice cultivars grown in the late season were not significantly related to those grown in the early season. Our study suggests that it is feasible to select high-yielding short-duration cultivars from existing early-season rice cultivars for machine-transplanted late-season rice production. Special tests by growing alternative early-season rice cultivars in the late season should be done to determine their growth duration and grain yield for such selection.

Both short- and long-term effects of fertilizers on crops and soils are often studied only in arid or paddy soils, whereas less is known about the long-term effects in paddy-upland rotations, particularly with multiple crops and frequent tillage in subtropical areas. Therefore, an 18-year field experiment was initialized to assess the effects of different types of fertilization (no fertilizer; chemical fertilizer (CF); and manure in combination with CF (MCF)) on yield and soil chemical and microbial properties in a crop rotation involving rice (Oryza sativa L., summer), rapeseed (Brassica campestris L., winter), tobacco (Nicotiana tabacum L., the following summer), and hairy vetch (Vicia villosa Roth, the following winter). MCF caused higher yields of rapeseed grains and tobacco leaves than CF after 3 or 4 years of implementing the experiment, while rice yields varied little between MCF and CF, with one exception in 2011. Compared with the initial soil properties, providing soil with MCF increased organic matter (OM), while the opposite trend was found with CF. Higher microbial biomasses, enzyme activities, bacterial operational taxonomic units, and richness and diversity indexes of bacterial communities were found in soils receiving MCF, implying the improvement of soil microbial properties in the paddy-upland rotation system with multiple crops and frequent tillage. The experimental soils under varying fertilization were dominated by four bacterial phyla (Proteobacteria, Acidobacteria, Actinobacteria, and unclassified groups), which accounted for approximately 70% of the 16S rDNA sequences. Among the top 20 predominant bacteria, 14 were commonly found in all soil samples irrespective of which fertilizer treatment was implemented. Thus, the presence of those bacteria was stable in the soil and to some extent was influenced by fertilization. Most of them were facultative anaerobic bacteria, which can adapt to both anaerobic paddy soil and aerobic drylands. The dominant bacteria at various taxonomic levels found in soils might reflect multiple soil processes such as OM turnover, nutrient cycling, physical structure formation, and xenobiotic detoxification.

The aim of this study was to compare the effects of cowpea green manure and inorganic nitrogen (N) fertilizers on yields of winter wheat and soil emissions of nitrous oxide (N2O). The comparisons included cowpea grown solely as green manure where all biomass was terminated at maturity by tillage, summer fallow treatments with 90 kg N ha−1 as urea (90-N), and no fertilization (control) at planting of winter wheat. Fluxes of N2O were measured by closed chamber methods after soil incorporation of cowpea in autumn (October–November) and harvesting of winter wheat in summer (June–August). Growth and yields of winter wheat and N concentrations in grain and straw were also measured. Cowpea produced 9.5 Mg ha−1 shoot biomass with 253 kg N ha−1 at termination. Although soil moisture was favorable for denitrification after soil incorporation of cowpea biomass, low concentrations of soil mineral N restricted emissions of N2O from cowpea treatment. However, increased concentrations of soil mineral N and large rainfall-induced emissions were recorded from the cowpea treatment during summer. Growth of winter wheat, yield, and grain N concentrations were lowest in response to cowpea treatment and highest in 90-N treatment. In conclusion, late terminated cowpea may reduce yield of winter wheat and increase emissions of N2O outside of wheat growing seasons due to poor synchronization of N mineralization from cowpea biomass with N-demand of winter wheat.

The area of dry-season rice (Oryza sativa L.) has rapidly increased in Cambodia owing to the large-scale development of irrigation infrastructure. But little is known of potential productivity and adaptive crop management. The objective of our study was to evaluate potential yield and nutrient requirements of dry-season rice in Cambodia, and the economic feasibility of soil-specific management recommended by the government. Field experiments were conducted on four soil types (Bakan, equivalent to Alfisol; Krakor, Inceptisol; Prateah Lang, Plinthustalfs; and Toul Samroung, Endoaqualfs) in four provinces (Battambang, Kampong Thom, Pursat, and Siem Reap) during the 2016 and 2017 dry seasons to compare 14 (2016) and 8 (2017) N-P-K combinations. Grain yield ranged from 1.0 to 5.5 t ha−1 in 2016 and from 1.3 to 6.7 t ha−1 in 2017. Potential yield from the experiments was 6–7 t ha−1 on Toul Samroung soil, 5–6 t ha−1 on Bakan soil, and 3–5 t ha−1 on Prateah Lang and Krakor soils. A rate of 140-60-60 kg ha−1 of N-P2O5-K2O was more than enough to achieve the best yields on any soil group. On the other hand, modest application rates in soil-specific management (44–78 kg ha−1 of N, 23–28 kg ha−1 of P2O5, 0–30 kg ha−1 of K2O) proved reasonable for resource-poor farmers in Cambodia, since the treatment always provided >75 % of the highest economic profit in high-input plots.

The regrowth of a C3 forage Stylosanthes capitata in a rain-fed field provided the weekly data collection in the southeast of Brazil during a heat event in autumn. A system named Trop-T-FACE simulated the free-air carbon dioxide enrichment and the enhanced temperature in four climatic regimes: current atmospheric conditions (Control), CO2 enrichment (600 ppm, eC), warming (2 °C above ambient canopy temperature, eT), and a combination of eC + eT. The area and biomass of foliage per shoot decreased, and the number of flowers per shoot and flowered ramification increased under single eC treatment besides the increment in palisade parenchyma of leaves. Increased investment in flowering in eC occurred notably when the soil water content was higher than 0.30 m3 m–3. Single eT treatment also impaired the area or biomass of foliage production per shoot, raised the shoot mortality, and promoted the increment of the spongy leaf parenchyma. There was some mitigation of the adverse effects of foliage production of eT or eC in eC + eT, but under this combined treatment, the shoot mortality also increased. Changes in leaf tissues under eC or eT or some mitigation of adverse effects in eC + eT did not offset the constraints on leaf growth per shoot. The harmful impact on foliage production by eC, eT, or eC + eT under rain-fed conditions indicated no advantages for feeding the livestock with the C3 forage S. capitata in expected climate change under field conditions.

The effects of straw alone or combined with industrial and agricultural wastes as fertilizers on greenhouse gas (GHG) emissions are still poorly known in cropland areas. Here, we studied the effects of 3.5 Mg ha−1 straw and 3.5 Mg ha−1 straw combined with 8 Mg ha−1 of diverse wastes on GHG emission in a subtropical Jasminum sambac plantation in southeastern China. There were five treatments in a completely randomized block design: control, straw only, straw + biochar, straw + steel slag, and straw + gypsum slag. Emissions of carbon dioxide were generally higher in the treatments with waste than in the control or straw-only treatments, whereas the contrary pattern was observed in CH4 and N2O emission rates. Moreover, the total global warming potentials (GWPs) were no significantly higher in most of the amended treatments as compared to the control and straw-only treatments. In relation to the treatment with only straw, GWPs were 9.4% lower when steel slag was used. This finding could be a consequence of Fe amount added by steel slag, which would limit and inhibit the emissions of GHGs and their transport from soil to atmosphere. Our results showed that the application of slags did not increase the emission of GHGs and that the combination of straw with steel slag or biochar could be more effective than straw alone for controlling GHGs emission and improve soil C and nutrient provision.

Highly weathered soils from humid tropics naturally have low contents of available potassium (K) to plants. Under these conditions, the K deprivation can change the equilibrium among cations in the soil and the nutritional status of some crops as soybean (Glycine max (L.) Merrill). A field experiment related to K fertilisation, spring soybean and diverse species of fall/winter crops, such as wheat (Triticum aestivum L.), corn (Zea mays L.), sunflower (Helianthus annuus L.) or oat (Avena strigosa L.), has been carried out in Southern Brazil since 1983. The K deprivation for 8 years reduced soybean grain yield and the K contents in soil and plant tissues. K extractants, such as Mehlich-1 and ion exchange resins, had diverse sensitivities with the variation in the K exchangeable contents induced by K rates. The increased soil K content after K fertilisation reduced calcium (Ca) and magnesium (Mg) contents in index leaves and altered its contents in the soil extracted by 1 mol L−1 KCl and ion exchange resins. Among the micronutrients, only B contents changed due to increased K rates, and had significant correlations with K and Ca contents in index leaves. The calculated Diagnosis and Recommendation Integrated System (DRIS) indices were compatible with soybean yield and K contents in soybean index leaves.

ANOVA, one of the most common statistical methods applied in agronomy, offers a variety of results we can report when analyzing designed experiments. The focus, of course, is on treatment means, but what should we report to characterize precision? Should we choose treatment standard deviations (SDs) or standard errors of the mean or standard errors of the difference (SEDs)? We discuss why treatment raw SDs should not be reported as the result of ANOVA, and point out that most of the time it is SEDs that should be provided.