Modeling chickpea growth and development: Leaf production and senescence

Quantitative information regarding leaf area development in chickpea (Cicer arietinum L.) is scarce. Data from four field experiments with a range of treatments including genotype, sowing date and plant density across four location-season combinations were analyzed to quantify main effects of temperature, photoperiod and plant population density on plant leaf area in chickpea. All experiments were conducted under well-watered conditions. Maximum rate of main stem node development was 0.72 nodes/d. Cardinal temperatures for node appearance were found as 6.0, 22.2 and 31.0 °C for base, optimum and ceiling temperatures, respectively. Plant density had no effect on cardinal temperatures for leaf appearance and phyllochron. Leaf senescence on the main stem started when the main stem had about 12 nodes and proceeded at a rate of 1.67% per each day increase in physiological day (a day with non-limiting temperature and photoperiod). Leaf production per plant versus main stem node number occurred in two phases; phase 1 when plant leaf number increased with a slower and density-independent rate (three leaves per node), and phase 2 with a higher and density-dependent rate of leaf production (8-15 leaves per node). A close relationship was found between the fraction of senesced leaves per plant and the same fraction on the main stem. The average leaf size per plant increased from 4 cm when there were 10 nodes on the main stem and stabilized at 10.8 cm when there were 21 nodes on the main stem. Plant density and sowing date did not affect leaf size. Plant leaf area was also predictable directly from main stem node number. The relationships found in this study can be used in simulation models of chickpea