连作对马铃薯根系形态及吸收能力的影响

Effects of continuous cropping on morphology characteristics and absorptive capacity of potato root

研究了不同连作年限对马铃薯根系形态和养分吸收能力的影响。结果表明，连作降低了马铃薯根系活力、活跃吸收面积和总吸收面积，连作3年、4年和5年的根系活力比轮作分别下降了53.71%、66.84%和66.69%，活跃吸收面积分别下降了57.6%、75.7%和75.6%，总吸收面积分别下降了51.4%、67.9%和67.6%；连作明显增加了0～0.5 mm和0.5～1.0 mm直径范围内的总根长、表面积、根体积和根尖数，连作3年、4年和5年在0～0.5 mm直径范围内的总根长和根尖数比轮作分别显著增加了24.9%、35.0%、35.4%和13.4%、21.0%、23.1%；连作1年和2年地块的块茎产量差异不显著，但连作3年后块茎产量较轮作下降了45%以上。由此可见，在当地生态环境和栽培及品种条件下连作的阈值年限可能为2年，马铃薯根系吸收能力的下降是导致产量下降的主要原因之一，根系生长增加是马铃薯应对连作逆境的主动性适应机制。

A field experiment was conducted to understand the mechanism underlying the reduction in potato yield under continuous cropping. The results showed that the activity of root system, root active absorption area, and total root absorption area were reduced as the continuous cropping year inc reased. Compared with rotation cropping, the activity of root system under continuous cropping for 3, 4, and 5 years decreased by 53.71%, 66.84%, and 66.69%, respectively, and similarly the root active absorbing by 57.6%, 75.7%, and 75.6%, and the total root absorbing by 51.4%, 67.9%, and 67.6%. The total root length, root surface area, root volume, and root tip number in root diameter of 0～0.5 mm and 0.5～1.0 mm obviously increased under continuous cropping. The tuber yield was no significantly different between 1 year and 2 years of continuous cropping, while it decreased by more than 45% compared with rotation cropping for 3 years of continuous cropping. It is thus suggested that the threshold of potato continuous cropping be no more than 2 years in the target area. In addition, the reduction in nutrient absorptive capacity and the increase in root growth increase were responsible for the yield loss of potato under continuous cropping.