连作对甘肃中部沿黄灌区马铃薯干物质积累和分配的影响

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

甘肃省中部沿黄灌区是全国重要的加工型马铃薯生产基地，因集约化种植带来连作障碍问题已严重影响到农业产业的健康发展，所以探索连作对马铃薯块茎产量形成的影响与机制十分必要。根据田间定位试验，以前茬为玉米的地块作对照，设连作1～5年处理，采用常规方法，调查连作对马铃薯产量、干物质积累和分配以及花后干物质积累和转运的影响。结果表明，与对照相比，短期（1～2年）连作未表现连作障碍现象，连作第3年，块茎产量显著下降，降幅达21．68％～75．67％，单薯重量变化是产量下降的直接原因；马铃薯整株和块茎的干物质积累均表现出明显的“S”型曲线特征，连作缩短干物质快速增长期时间和减少于物质平均积累速度；也影响马铃薯植株干物质在不同器官间的分配比例，特别是明显增加根系干物质分配比例。在块茎产量的形成过程中，长期连作导致营养器官花前贮藏干物质向块茎转运的贡献增加，而花后同化产物向块茎直接输入的贡献降低。长期连作条件下马铃薯植株库源关系的失衡是导致块茎产量降低的主要原因。

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 statis- tical 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, espe- cially 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 decreased 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.