Modelling the impact on navy beans and vining peas of temperature changes predicted from global warming

Abstract

Conservative estimates of global warming suggest that average daily temperature may be raised by 0.5–1.5 °C by the middle of the next century. This would have an impact on agricultural and horticultural production in the U.K., and may result in a changing distribution of crops and the introduc tion of crops which cannot currently be grown in the U.K. The effect of a warmer climate on navy beans (Phaseolus vulgaris) and vining peas (Pisum sativum) was studied with the aid of a heat unit model. Total thermal receipt for the current and a warmer climate over the growing season of navy beans is compared with thermal requirement (sowing to crop maturity) of the crop. The analysis suggested that parts of Southern England would become thermally suitable for navy bean production, given relatively little global warming (0.5 °C). For vining peas, the contraction of the harvesting period due to a warmer climate, with a resulting increase of risk of a lost crop, is examined by using an accumulated day degree time scale from the start of harvest to the time when the crop is too mature. This analysis indicated that the time available for vining pea harvesting (determined by tenderometer values) may decrease by up to 25 per cent, which would significantly increase the risks in harvesting at the optimum time in traditional production areas. It is suggested that growing vining pea crops at more northerly latitudes than currently would help to compensate for the tendency of increased warming to reduce the period for which the crop could be harvested at optimum maturity.