Effect of sink removal on yield and yield components of chickpea (Cicer arietinum L.) under different nitrogen fertilizer levels and irrigation regimes

Introduction Chickpea (Cicer arietinum L.), an annual with indeterminate growth, is one of the most important food legumes. Loss of seeds due to pod borer (Heliothis armigera) attack is prevalent. Such loss of pods may affect the yield and yield components. The source-sink relationship changes during growth stages. Some factors influence this relationship including nitrogen fertilizer and water. This experiment was conducted in order to study the effects of nitrogen fertilizer, supplementary irrigation and depodding on yield and yield components of chickpea (var. ILC482). Materials & Methods The experiment was conducted as split-split plot based on a randomized complete block design with three replications at Agricultural Research Station of Ferdowsi University of Mashhad, during growing season of 2012. Main plot was nitrogen fertilizer including 30, 75 and 150 kg N/ha and sup plot was irrigation regimes including full irrigation, supplementary irrigation at flowering and supplementary irrigation at flowering, seed podding and depodding including 0, 25%, 50% and 75% as sub subplot. Leaf and stem dry weight, seed weight per plant, shoot weight, pod number per plant, grain number per plant, 100-seed weight and harvest index of chickpea were all recorded. Results & Discussion The results indicated that all traits excluded of harvest index were higher in 150 kg N/ha treatment than other treatments. Nitrogen rate of 150 kg/ha produced the highest seed weight (3.8 g/plant). The highest harvest index (36%) was obtained from 30 kg/ha N treatment. Supplementary irrigation at flowering and podding stages with grain yield 4.4 g/plant was higher than full and supplementary irrigation at flowering. Supplementary irrigation at flowering and podding stages produced the highest harvest index (39%). In irrigation regimes including full irrigation and supplementary irrigation at flowering stage, 75% depodding decreased seed weight to 60%, but this was 45% in Supplementary irrigation at flowering and podding stages. In this interaction, full irrigation and 0% depodding (control), produced the highest seed weight (195 g/m2). The lowest seed weight (40 g/m2) was obtained from supplementary irrigation at flowering stage and 75% depodding. Supplementary irrigation at flowering and podding stages with 25% depodding produced the highest harvest index (45%) too. Increase of harvest index mostly was related to improve photosynthesis and remobilization in mid drought stress and also