Variation in Thermal Time Model Parameters between Two Contrasting Chickpea (Cicer arietinum) Cultivars
A laboratory experiment was carried out to determine the effect of temperature on germination and early seedling establishment and to study the variation among thermal time model parameters for two contrasting chickpea cultivars. Seeds were subjected to six constant temperatures from 10˚C to 35˚C. A complete randomized design was used with four replications. Analysis of variance showed significant differences (p < 0.05) among all characters studied. The final germination percentage of both cultivars significantly (p < 0.05) increased with increasing temperature up to 25˚C, and thereafter there was a sharp decrease in final germination at super optimal temperatures (30˚C and 35˚C). Desi type cultivar (small seeded) locally called “Jabel Marra” significantly (p < 0.05) exhibited higher final germination percentage and germination rate compared with the smaller seeded kabui type cultivar “Shendi” at all temperatures. The median (θT(50)) of the thermal time was significantly (p < 0.05) different between the two chickpea cultivars. The large seeded cultivars (Shendi) recorded significantly (p < 0.01) higher median thermal time than the small seeded cultivars (Jabel Marra). The results also revealed significant (p < 0.01) differences between the two cultivars on the other parameters of thermal time model. On the other hand, the small seeded cultivar (Jabel Marra) scored lower total dry matter and temperature tolerance index (TTI) compared with the large seeded cultivar (Shendi) at all temperatures studied.