钾肥运筹对烤烟钾吸收利用的影响

【目的】烟叶含钾量低是我国生产优质烟叶的主要限制因素之一,困扰着我国烟草生产。本文研究了钾肥运筹对四川省凉山州主栽烤烟品种云烟85钾吸收利用的影响,为当地合理施用钾肥提供科学依据。【方法】以云烟85为试验材料,采用大田试验,研究钾肥用量对云烟85的产量和钾积累量的影响,确定相对较优的钾肥用量及烤烟的钾积累高峰期;在此基础上,研究钾肥施用方式对云烟85的产量、品质、钾积累量和钾肥利用率的影响。【结果】烤烟产量和钾积累量随钾肥用量的增加先升高后降低。钾肥用量为158 kg/hm2(约为当地常规用量的75%)时,云烟85的烟叶产量(2238.2 kg/hm2)与最高产量(2239.1 kg/hm2),钾积累量(52.16 kg/hm2)与最高钾积累量(53.47 kg/hm2)之间差异较小,在土壤速效钾含量处于丰富(≥200 mg/kg)水平时,降低25%左右的钾肥用量可提高种植云烟85的经济效益。烟草生育周期内,钾积累速率呈双峰曲线,钾积累高峰出现在旺长后期(移栽后50~65 d)和中部叶成熟期(移栽后85~95 d)。在钾肥施用总量158 kg/hm2条件下,在烤烟进入旺长后期(移栽后50~65 d)和中部叶成熟期(移栽后85~95 d)之前,分别追施钾肥总量的15%~20%,打顶后5 d和10 d内烟叶钾积累量的降低比例分别比常规施肥减少了37.2~42.0和15.4~60.3个百分点,且成熟期中、上部烟叶的含钾量显著增大,分别达3.21%和3.37%,钾肥利用率比当地常规施肥方式高出12~18个百分点。【结论】钾肥追施时期调整至钾积累高峰期之前,有望提高成熟期的烟叶含钾量。在本试验条件下,种植云烟85时应将钾肥用量控制在158 kg/hm2左右,并在旺长后期和中部叶成熟期分别追施钾肥总量的15%~20%,可有效提高钾肥利用率和成熟期的烟叶含钾量,达到高产优质的目的。

Effect of potash management on potassium absorption and utilization of flue-cured tobacco

【Objectives】Low K content in tobacco leaves has been one of the limiting factors for the good quality of tobacco in China, plagued the tobacco production in China. In this paper, the K absorption and utilization of flue-cured tobacco affected by potash management were studied in Liangshan City, Sichuan Province, so as to provide a scientific basis for rational fertilization of tobacco. 【Methods】 A field experiment was conducted to study the appropriate K application rate and the peak K accumulation of the tobacco cultivar Yunyan85. Based on this research, another field experiment was carried out to study the influence of potash management on yield, quality, and K accumulation and utilization efficiency of Yunyan85. 【Results】 The yield and K accumulation of flue-cured tobacco are increased firstly and then decreased with the increase of potash rates. When the K application rate was 158 kg/hm2, about 75% of the local common K rate, the yield is 2238.2 kg/hm2 and the K accumulation is 52.16 kg/hm2, which are slightly lower than the highest yield (2239.1 kg/hm2) and the highest K accumulation (53.47 kg/hm2) in the experiment. So, the K application rate can be reduced by 25% to improve the economic benefits of planting tobacco production when the available K content of soil is ≥200 mg/kg. The K accumulation shows a double-peak curve during the whole growing stage of tobacco plants, the two peaks appear at the later vigorous growth stage (50-65 days after transplanting) and middle leaf maturity stage (50-65 days after transplanting). At the K application amount of 158 kg/hm2, 15%-20% of total K fertilizer were top dressed before the later vigorous growth stage (85-95 days after transplanting) and middle leaf maturity (85-95 days after transplanting), the reduce proportion of K accumulation in tobacco leaves at the 5th and the 10th day after topdressing are reduced by 37.2-42.0 and 15.4-60.3 percent points, compared with conventional fertilization. Also the K contents in the middle and upper leaves are significant increased and reached to 3.21% and 3.37% respectively, and the K utilization efficiency is increased by 12-18 percent points. 【Conclusions】 The suitable ratio of basal and topdressing is beneficial to the quality of tobacco leaves. In this research, under the total K application rate of 158 kg/hm2, topdressing 15%-20% in the later vigorous growth stage and middle leaf maturity is expected to reduce the spillover rate of K and increase the K utilization efficiency and K content in tobacco leaves at the maturity, achieving the aim of high-yield and good quality.