Determination of cardinal temperatures and thermal time requirement during germination and emergence of chickpea genotypes (Cicer arietinum L.)

Determination of cardinal temperatures during seed germination and emergence as well as the thermal time requirement for each stage is essential in crop management and modeling of plant growth and development. Two experiments were conducted to predict cardinal temperatures and thermal time requirement for germination and emergence of chickpea genotypes. In the first experiment، seed germination responses of six chickpea genotypes (MCC361، MCC951، MCC180، MCC873، MCC13 and MCC463) at seven temperature regimes (3، 5، 10، 15، 20، 25، 30 and 35°C) in a controlled condition were evaluated. The trial was carried out as split plot based on a completely randomized design with three replications using 10 seeds per Petri dish. Seed germination percentages and days to 50% germination (cumulative) were determined. Cardinal germination temperatures using non-linear regression between germination rate and temperature (R50 as y and T as x) were estimated. Temperature function، Dent like model was used to determine seed germination rate. In the second experiment، traits mentioned in first experiment were studied for emergence of chickpea genotypes، with nine planting dates considered as main plots. Therefore، the experiment conducted as split plot based on a complete block design with three replications in the soil. Based on the results، both base temperature for germination and emergence were stable traits and there were not significant differences among genotypes in this respect. Average base temperature of genotypes for germination and emergence were estimated 4. 2˚C and 6. 1˚C، respectively. Also، the average optimum temperatures of genotypes for germination differed from 20. 4˚C to 26. 5˚C، respectively and for emergence they were differed from 24. 0˚C to 26. 8°C، respectively. There was no considerable genetic diversity for physiological days and thermal time required for germination and emergence of chickpea genotypes. There was a highly significant positive correlation between observed and predicted days to germination and emergence of chickpea using Dent like model. Therefore، this model can be used for simulating germination and emergence times of chickpea.