钾肥用量对棉花生物量和产量的影响

近年来我国棉花生产，要么产量受制于缺钾引起的早衰，要么过量施钾导致生产成本增加和养分流失。然而，最适宜棉花生物质积累和增加产量的钾肥用量并不明了，因而也无适宜的施钾量推荐给农民。因此，采用大田试验(随机区组设计)和盆栽试验研究了钾肥用量对棉花(华杂棉H318)生物量和产量的影响。结果表明，K2处理(225 kg hm^–2)产量(1341 kg hm^–2)最高，单位面积成铃数(74个 m^–2)最多，盆栽试验结果具有相同趋势。同样，K2的棉株生物量，在各个取样时期都最大，尤其是生殖器官生物量。在5个钾肥用量(0~450 kg hm^–2)处理中，棉株生物质快速累积期几乎同时启动，但终止期存在一定差异。棉株生物质快速累积期间，K2处理无论是营养器官还是生殖器官生物质的平均累积速度、最大累积速度均最高。可见，在长江中游棉区中等肥力棉田，同时施用N 300 kg hm^–2和P₂O₅ 90 kg hm^–2的条件下，钾肥用量225 kg hm^–2更有利于棉花提高产量，因为在这一用量条件下棉株生物质累积速度最快、累积量最大。

Effect of Potassium Application Rate on Cotton (Gossypium hirsutum L.) Biomass and Yield

Cotton production in China is recently confronted with either yield loss by plant early senescence resulted from potassium (K) deficit, or cost rise and nutrients leaching by K excess use. However, the optimal K rate in term of cotton biomass production and yield remains uncertain to make a recommendation for the farmers. Both field with random block design and outdoor pot trials were carried out to determine how cotton (Gossypium hirsutum L. vs. Huazamian H318) biomass and yield were affected by K rates. The result showed that K2 (225 kg ha^–1) harvested the highest yield (1 341 kg ha^–1) and bore the most bolls (74 bolls per square meter) in the field trial, with a similar trend for the pot trial. As expected, cotton biomass of K2 was the highest at each of the sampling stages, especially for reproductive organs. Cotton biomass initiated simultaneously the fast accumulation period (FAP), but terminated the period differently among five K rates (0–450 kg ha^–1). During the period, K2 had the highest biomass accumulation rate both on an average and in the maximum, and for vegetative and reproductive organs. It suggests that K rate of 225 kg ha^–1 be optimal to produce a favorable yield in the field of medium fertility when N 300 kg ha^–1 and P₂O₅ 90 kg ha^–1 are applied in the Middle Reaches of Yangtze River, in which condition cotton plants accumulate greater amount of biomass with a higher accumulating rate.