Gene-ecological investigations in Pisum mutants

Summary

Six mutants and nine recombinants of Pisum sativum were grown along with the mother variety at Kurukshetra, North India. The findings obtained were compared with those obtained for the same material grown at Bonn, Germany. The following observations were made.

Stem length and degree of branching are influenced differentially in the various genotypes tested in India as a consequence of a specific reaction of the genes to the climatic conditions. A gene for weak stem fasciation and gene efr for earliness in a specific gene combination are unable to express their action in North India whereas they are fully active in Germany. Furthermore, in Kurukshetra early flowering of some recombinants does not result in early ripening because their seeds require about double the time for full ripening than those of the mother variety.

At Kurukshetra, recombinant R 674A proved to be highly heat susceptible. All the plants died in early stages of ontogenetic development. Four other genotypes died due to heat before completing seed ripening. One mutant and three recombinants were found to be more tolerant to powdery mildew attack than the mother variety and Indian local lines. The seed production of eight genotypes in relation to that of the initial line was essentially better in North India than in Germany. They are obviously better adapted to the semi-arid conditions. Some of them appear to be useful for pea breeding in India. In contrast, a fasciated mutant, high yielding in Germany, is not able to express this potentiality at Kurukshetra. At Udaipur (Rajasthan, Western India), this mutant is unable to flower. Another four genotypes, tested at both Indian locations, exhibited an essentially poorer seed production at Udaipur than at Kurukshetra due to some ecological factors.

The findings indicate a specific response of some of the genotypes tested to the specific ecological conditions of the three locations, their response differing from that of the mother variety demonstrating thereby a different adaptational optimum.