Nitrogen Utilization and Yield Determination of Spring Mediterranean Chickpea as Influenced by Planting Date and Environmental Conditions

Growth, yield components, and N utilization patterns of spring chickpea (Cicer arietinum L.) cultivars were investigated for 2 years under Mediterranean conditions, and the associations with seed yield were identified. Three desi-type cultivars (Andros, Kassos, and Serifos) and one kabuli-type cultivar (Zehavit-27) were assessed under March and April planting. April planting resulted in higher early dry matter and N accumulation, which were not reflected in increased seed yield compared with March planting. Chickpea growth was co-limited by both source and sink limitations induced by the environment during the seed filling period. Most of the variation (>94%) in seed yield was accounted for by the variation in seeds m(-2) rather than that in seed size. The seed number was reduced on average by 7-18.2 seeds m(-2) day(-1) of planting delay, with the penalty being higher the year with the greater yield potential. In addition, the number of seeds m(-2) was reduced by 21% and by 18% for every degree Celsius increase in mean and maximum temperature during the early reproductive period, respectively. Biomass production efficiency (33.9-51.6kgkg(-1)) was greater than nitrogen utilization efficiency (17.8-27.2kgkg(-1)). The proportion of total plant N allocated to the seeds at maturity (i.e., nitrogen harvest index) was the limiting factor for enhanced N utilization. Overall, March planting may ameliorate growth limitations by bringing the reproductive stage earlier and, consequently, it may be more advantageous in terms of both seed yield and seed quality compared with April planting.