Effects of Continuous Cropping on Dry Matter Accumulation and Distribution of Potato Plants in the Yellow River Irrigation Areas of Middle Gansu Province

Abstract

The Yellow River irrigation areas of middle Gansu Province is one of the major growing regions of processing potato in China and potato is often planted continuously by farmers eager to maximize profit, this practice results in the severe decline in tuber yield and also affects the healthy development of the potato industry locally. It is necessary to explore effects of continuous cropping on potato yield formation. The long-term field experiment contained five potato cropping treatments, corresponding to continuously plant potato crop over 1–5 years respectively, in addition, maize-potato rotation plot was used as the control, namely, non continuous potato cropping. We made an attempt to understand the effects of continuous cropping on potato tuber yield, dry matter accumulation and distribution, and accumulation and translocation of dry matter during post-anthesis. There were no statistical differences in tuber yield under the short-term continuous cropping compared with control, however, significant decline in tuber yield by 21.68%–75.67% occurred after three years of continuous cropping, which was mainly derived from the decline in the average fresh-weight of individual tuber. Dynamics of dry matter accumulation in the whole plant and tuber both showed the S curve feature, and the continuous cropping decreased the average rate and the duration in dry matter accumulation during quickly accumulative period of potato compared with control. The continuous cropping also affected dry matter distribution, especially increased dry matter distribution ratio in root compared with control. For tuber yield formation, the long-term continuous cropping increased the contribution of translocation of dry matter stored in vegetative organs during pre-anthesis, whereas de-creased the contribution of direct assimilate accumulation in tuber during post-anthesis. In conclusion, the long-term continuous cropping leads to an imbalance of sink-source relationship of potato plants, which is the main cause of tuber yield decline.