Effects of Climatic Factors on the Growth and Development of the Field Bean (Vicia fabaL. var.minor)

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Abstract
The effects of weather on seed and haulm yields and yield components in field experiments with field beans were analyzed by means of a regression model taking into account daily values of hours of bright sunshine, mean night temperature and an estimated difference between potential and actual evapotranspiration. The final yields of both seeds and haulm were positively affected by high insolation during the early growth stages. In seed yield this positive effect continued throughout the greater part of the flowering phase, while haulm yield was negatively affected by increasing insolation during flowering and early ripening. The seed yield response to hours of bright sunshine became gradually negative towards the end of the ripening phase, at which time the haulm yield showed a curvilineal response with an optimum at about 9 h. The independent effect on seed yield of rising temperature was generally negative during the vegetative growth phase. During the latter phase the negative effect was particularly pronounced when soil moisture was plentiful, whereas there was a beneficial temperature effect when soil moisture content was low. In haulm yield there was a curvilineal response to temperature, with an optimum at 12.degree.-15.degree. C from early in the flowering phase and almost up to harvesting. Soil moisture deficit affected seed yields negatively during the last part of the vegetative phase and the flowering phase. The water deficit was never severe for long periods late in ripening; possible confounding with associated factors is discussed. The response surfaces of various yield components were only to a limited extent similar to those of their associated yields. Nor were the correlations between yield and yield components particularly strong. Most of the changes are a result of weather effects on assimilation, developmental rates and translocation processes.