2 results
Grain-filling patterns and nitrogen utilization efficiency of spelt (Triticum spelta) under Mediterranean conditions
- S. D. KOUTROUBAS, S. FOTIADIS, C. A. DAMALAS, M. PAPAGEORGIOU
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- Journal:
- The Journal of Agricultural Science / Volume 152 / Issue 5 / October 2014
- Published online by Cambridge University Press:
- 31 May 2013, pp. 716-730
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The identification of factors determining the adaptation and nitrogen (N) utilization of spelt wheat is important for the successful introduction of the crop to a new environment. The present study was carried out to investigate the relative importance of grain-filling rate and duration of grain growth and to analyse the nitrogen utilization efficiency (NUtE) and biomass production efficiency of spelt under Mediterranean conditions. The performance of spelt was evaluated in relation to a well-adapted bread wheat cultivar. Three spelt cultivars (Ressac, Poème and Cosmos) and one bread wheat cultivar (Centauro) were grown for two growing seasons on a silty clay soil under two N levels (0 and 100 kg N/ha). Grain-filling parameters were estimated using the cubic polynomial model. This model provided good fit to the grain-filling data of spelt cultivars, with high coefficients of determination (R2) that ranged from 0·868 to 0·999. Cultivar differences were found for all grain-filling parameters studied, and these differences accounted for most of the variation observed within each particular grain-filling component in both years. Grain filling of spelt plants took place under adverse environmental conditions, mainly high temperatures, which led to a shortening of the grain-filling period. This fact was not fully compensated by the increase in the grain-filling rate, and eventually resulted in a reduction of the final spelt grain weight. Selection for early-flowering cultivars could be a successful strategy to moderate the influence of the environment on grain filling and improve the adaptation of spelt under Mediterranean conditions. The mean grain-filling rate was positively correlated with dry matter translocation, suggesting the crucial role of reserve assimilates in the vegetative tissues for the grain growth of spelt. The efficiency of N utilization to produce biomass was greater during the grain-filling period than the vegetative period. Averaged across N application rates, NUtE in spelt ranged from 20·1 to 29·5 g grain/g plant N. Cultivar differences in NUtE were observed in both years. Grain yield per unit grain N (grain DM/grain total N at maturity) contributed more to the total variation in NUtE among spelt cultivars compared with N harvest index (NHI). Spelt showed lower NUtE values, probably due to its higher grain N concentration and lower NHI compared with wheat. Low straw N concentration at maturity may be an indicator of improved NUtE in spelt, as evidenced by the negative relationship detected between the two variables. These results provide a better understanding of factors related with the adaptation and N utilization of spelt under Mediterranean conditions.
Growth and nitrogen dynamics of spring chickpea genotypes in a Mediterranean-type climate
- S. D. KOUTROUBAS, M. PAPAGEORGIOU, S. FOTIADIS
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- Journal:
- The Journal of Agricultural Science / Volume 147 / Issue 4 / August 2009
- Published online by Cambridge University Press:
- 11 May 2009, pp. 445-458
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Chickpea (Cicer arietinum L.) is an important legume of rainfed farming systems, contributing to the sustainability of production and reducing the need for nitrogen (N) fertilization through fixing atmospheric N2. The relative importance of factors causing variations in growth, seed yield, N accumulation and N utilization efficiency among spring chickpea varieties grown in a Mediterranean-type climate was investigated in field experiments conducted in 2003 and 2004. Five chickpea varieties were grown in a silty clay soil in the farm of the Democritus University of Thrace in Orestiada, Greece. Yearly differences in plant growth and productivity were observed and were mainly associated with the variations in the weather parameters between the growing seasons. Nitrogen utilization efficiency (NUE) for biomass production during the seed-filling period was higher compared with that during the vegetative period. NUE for seed yield (SY) ranged from 18·3 to 24·5 g dry matter (DM)/g N and was positively correlated with seed yield, suggesting that high SY was associated with more efficient exploitation of N. When the environmental conditions favoured high early N accumulation, the differences among varieties in NUE were mainly due to the differences in N partitioning at maturity, e.g. the nitrogen harvest index (NHI). The amount and the efficiency of N content at the beginning of seed growth (growth stage (GS) R5) that was translocated to the seed differed among varieties and ranged from 7·0 to 16·6 g N/m2 and from 68·2 to 86·8 g DM/g N, respectively. Most of the variation (0·96) between varieties in N translocation could be accounted for by the differences in total N content at GS R5. N losses from the plant foliage between 0·61 and 9·92 g N/m2 were detected during the seed-filling period when SY was low and N content at GS R5 was high.