Inheritance pattern of cold tolerance in pigeonpea [Cajanus cajan(L.) Millsp.

Abstract

Among all the abiotic stresses, cold is one of the important factor limiting crop productivity. Medium and late maturing varieties cover most of the cultivated area of pigeonpea and therefore the chances of facing cold/frost are prominently high. Northern parts of the country are witnessing very low temperature during the last fort night of December and first fortnight of January, which is conducive for frost injury and the susceptible lines exhibit frost symptoms. Screening of 302 germplasm/lines of pigeonpea comprising of varieties and advance materials against frost injury during the years 2016-2018 facilitated to identify tolerant and susceptible lines. One hundred and forty one lines did not show any injury symptom, whereas 120 were classified under score 1 and 17 lines showed moderate symptoms to frost injury. A highly frost tolerant (insensitive) line ICP 10509 was crossed to susceptible (sensitive) line ICP 11182 to study the nature of frost injury and mode of inheritance. The F1 hybrid showed tolerance to frost injury with 1-2 leaves showing little symptom (score 0-1) indicating dominance of the trait. The F2 population segregated into tolerant (216 plants) and susceptible individuals (91 plants) fit well into expected ratio of 3(T): 1(S) (P value = 0.06027) signifying that frost tolerance (insensitivity) is controlled by a single dominant gene. The proposed hypothesis was verified by backcross populations; B1 (F1 x ICP 11182) segregating into 1(T):1(S) ratio (P value = 0.1237), whereas, all the plants in B2 (F1 x ICP 10509) generation exhibited tolerance to frost injury. The identification of a single gene exhibiting tolerance to frost injury may be useful for developing frost tolerant genotypes.