不同氮水平对旱地覆膜马铃薯干物质积累与分配的影响

针对马铃薯生产中存在的氮肥施用过量问题,通过田间试验,研究了不同氮肥水平(0、50、100、150、200、250 kg·hm~(-2),分别对应T1、T2、T3、T4、T5、T6处理)对旱地覆膜马铃薯"陇薯3号"的生育进程及其干物质积累与分配的影响。结果表明:施用氮肥显著推迟了马铃薯的生育进程,随施氮量的增加,马铃薯的生育期延后,各施氮处理的干重平衡期比不施氮肥的对照处理(T1)推迟了2~16 d;施用氮肥显著增加了马铃薯全株和块茎干物质快速积累的持续时间(Δt),随施氮量的增加,与T1相比,全株Δt增加了2~14 d,块茎Δt增加2~10 d;马铃薯整株和块茎干物质积累均表现出明显的"S"曲线特征。不同氮水平对成熟期马铃薯干物质在不同器官中的分配比例也有显著影响,随施氮量的增加,成熟期茎和叶所占干物质比例明显增加,块茎所占干物质比例呈单峰趋势变化;不同氮水平也显著影响马铃薯块茎产量,与对照处理(T1)相比,T2处理增产17.86%,T3、T4、T5和T6分别减产6.88%、21.06%、27.05%和38.63%,说明过量施用氮肥会导致马铃薯减产,其本质是马铃薯库源关系的失调(施氮量超过50 kg·hm~(-2)时)。在本试验条件下,当目标产量为1.65 t·667m-2时,50 kg·hm~(-2)为经济最佳施肥量。

Effects of nitrogen rates on dry matter accumulation and distribution of potato plants under film mulching in dry land

Field experiment was carried out to evaluate the effect of nitrogen rates on growing stages and dry matter (DM ) accumulation of potato cv Longshu No .3 under film mulching in dry land .Six nitrogen rates ,0 (CK or T1 ) ,50 (T2) ,100 (T3) ,150 (T4) ,200 (T5) and 250 (T6) kg·hm-2 were used ,and field plots were arranged in a random-ized complete block design with four replications .The results showed that the application of nitrogen had significantly positive effect on the duration of growing stages of potato .Nitrogen applications obviously increased the duration of fast accumulation period (Δt ) for the whole plant and tubers ,being 2~14 days and 2~10 days ,respectively .Dynamics of dry matter accumulation in the whole plant and tuber both showed the “S”curve .The dry matter distribution of maturity potato responded differently to nitrogen .With the increase of nitrogen rates ,dry matter distribution ratio obviously in-creased in both stem and leaf ,while those of tuber increased first then decreased ,exhibiting a single peak curve .Com-pared with T1 ,T2 treatment increased the tuber yield by 17 .86% ,while those of T3 ,T4 ,T5 and T6 treatments were decreased by 6 .88% ,21 .06% ,27 .05% and 38 .63% ,respectively .The depressing effect of N on potato yield may be partly due to the disturbance in sink-source relationship of potato plants ,and it is suggested that 50 kg·hm-2 N be the economic rate of N fertilizer in this area .