Effects of a short period of drought on changes in tuber volume and specific leaf weight. II. Diurnal changes

Summary Single-stemmed potato plants, cv. Bintje, were grown on a nutrient solution under controlled conditions. They were exposed to a short drought stress, or remained untreated. Short-term changes in tuber volume and in specific leaf weight were measured non-destructively. Tubers from control plants increased rapidly in volume during the night and did not grow, or even shrivelled during the day. Tubers of stressed plants did not show a uniform response; some tubers markedly declined in volume during the day. The patterns of volume increase of stressed plants became erratic after the stress, mainly because some plants never fully recovered. Patterns of diurnal fluctuation in tuber volume were similar to diurnal changes in specific leaf weight; tubers within the same stressed plant sometimes reacted differently. In these cases the effects on the diurnal fluctuation partly reflected the long-term effects, reported in an earlier paper.