Abstract

It is a matter of common knowledge that the yields of rainfed crops is a mathematical function of the rainfall. The potency of rainfall varies, on the one hand, not only with its magnitude and distribution, but also with the nature of the inter-relation between these two features and on the other, with the stage of plant growth at the time of its incidence and with the condition and the nature of the soil. In a plant like cotton, the growing and fruiting phases of which extend over a long period, the effects of rainfall are made more complicated, and any attempt to dis-entangle this knotty complex will only be in the nature of crude approximations as many of the individual and combined reactions are still unknown. Yet, it is quite essential on the part of the plant-breeder and the agriculturist to know, in a broad outline at least, the behaviour of the plant under. various weather conditions and the critical periods at: which the rainfall will have the best or the worst effects.: This will enable the breeder to evolve a type which will have the best fit between the rainfall conditions prevailing in a locality and the plant, or to seek means to accelerate or retard the growth in such a way that the prejudicial effects may be mitigated, if not averted.

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