Selectivity of Cold Tolerant Chickpea Genotypes under Controlled Condition (Cold room)

Chickpea is the most important field crop among food legumes in Iran. According to the published statistic by agricultural ministry of Iran, cultivation area of chickpea varies between 550– 900 thousand hectares that more than of 90% them cultivated under dryland condition. More than 63% of country has cold and higher cold climates and more than 60% of drylands in Iran located in cold and highlands where temperature declines to -25°C in some years, with continues cold duration (more than 100 days per year). Reports show that the yield of chickpea is low in cold areas (about 500 kg.ha-1) because of the spring planting and lack cold tolerant cultivars suitable for autumn planting. In cold regions that absolute minimum temperature in winter reaches under -6°C till -12°C, studies showed that it may be complete damage occurrence if chickpea planted in autumn. Studies showed that planting of cold tolerance varieties increased the yield of chickpea almost twice. Hence, screening chickpea germplasms for cold tolerance will help to release new cold tolerant cultivars. The literature review suggests that most studies related to the evaluation and screening of chickpea cold tolerance were done under natural conditions (field), but the spatial and temporal variation in the weather under such circumstances may lead to different results. Researchers reported that using from controlled condition for screening cold tolerance genotypes in chickpea germplasm would prevent seasonal restrictions, saving time and increasing the accuracy of studies while eliminating unwanted factors. In order to study on cold tolerance of 33 Kabuli chickpea genotypes along with three controls (Saral, ILC 533 and Jam), this study carried out in square lattice design (6×6) with two replications under controlled condition (cold room) at Maragheh Dryland Agricultural Research Station, during growing season 2014-2015 . Ten seeds of each genotype after surface sterilized with fungicide (Benomile with 0.015%) planted in five cm depth in planting boxes (100×80×25 cm) at early autumn (29 September). In order to simulation of natural growth condition in autumn and acclimation of seedlings, planted boxes incubated outside of green house. Number of germinated seeds was recorded and seedling of genotypes at six-week stage, incubated in cold room. The temperature of cold room decreased two degrees in each hour up to minus 15°C and seedlings remained for one hour at this temperature. A thin layer of ice nucleation active bacteria sprayed on the surface of seedlings at -2°C in order to establish ice nucleation and prevent ultra-freezing of seedlings. Then temperature increased up to 4°C for three days and boxes transferred to green house for two weeks under 20±3°C. Frost resistance ratios (FRR) of genotypes calculated and analyzed. According to other studies and reports the genotypes with 0.91-1 and 0.81-0.90 FRR classified in highly resistance and resistance groups, respectively. Results showed that there was significant (p ≤ 0.01) differences in frost resistance ratio (FRR) among the investigated genotypes. Lines 14 (Flip98-138C* SEL99TER85074)*Sel.99th.15039, 28 (FLIP 00-84 C) and Saral cultivar had the highest FRR (100, 98 and 89 survived percentage, respectively) among the genotypes. Also Kaka cultivar and line 12 (Flip 98-28C*Flip 98-22C)* ICCV2 had the lowest frost tolerance among the studied genotypes. About 30% of genotypes could tolerate the frost damage, for example, genotypes 14 and 28 had between 0.9-1.0 ratio, whereas, the FRR of susceptible check (ILC533) was 0.13.  The existence of wide range of diversity for frost resistance among the studied germplasm would be useful to introduce new tolerant chickpea cultivars with autumn-sown potential. Moreover, the tolerance of Saral cultivar to frost stress, its cultivation under cold dryland regions could be recommended as the first frost tolerant variety in the country.