黄冠梨果实和叶片钾素积累特征及其对施钾的响应

Potassium accumulation in ‘Huangguan' pear fruits and leaves and their response to different potassium application

【目的】本研究通过研究黄冠梨果实和叶片钾素积累特征及其对不同施钾量的响应,探讨施钾对梨果产量和品质的影响,为梨园合理施钾提供依据。【方法】选取同一区域14年生不同产量水平的高(60~70t/hm^2)、中产(30~40 t/hm^2)两个黄冠梨园开展田间施钾试验。设置K_2O 0、150、300、450 kg/hm^2四个施钾水平(K0、K150、K300、K450),分别在幼果期、膨大Ⅰ期、膨大Ⅱ期、成熟期和果实收获后一个月采集叶片与果实样品,研究施钾对产量、果实品质、叶片和果实钾含量及钾积累量、钾肥利用率的影响。【结果】随施钾量增加高产园产量增加显著,K450处理比对照提高了16.9%;在中产园K300处理产量达到最高值,较对照提高了27.2%,K450与K300处理之间无显著差异。果实中可溶性糖含量和糖酸比随施钾量增加而提高,可滴定酸变化规律与之相反。从幼果期至成熟期,叶片与果实钾含量均呈下降趋势,施钾在不同程度上提高了钾素含量。叶片钾积累量在膨大Ⅰ期达到最大,随后积累量逐渐下降。果实钾在整个膨大期积累最多,占全生育期钾积累量的60%~79%;膨大期后高产园果实仍在迅速积累钾素,中产园积累减缓。落叶前叶片钾回流,高产园回流力度大于中产园。高产园果实收获和落叶移走钾量为258~314 g/plant,中产园为166~192 g/plant。在高产园K450处理和中产园K300处理下,果实和叶片内每积累1 kg钾素,高产园可增产414.0 kg,中产园增产405.2 kg。【结论】施钾促进了树体对钾素的吸收,果实产量和果实品质随施钾量增加有不同程度提高。膨大期是树体吸收钾素的最大效率期,建议在膨大期前追施钾肥。综合产量、肥料利用率及果实品质等各项指标,建议产量为60~70 t/hm^2的高产园适宜施钾量为450 kg/hm^2,产量为30~40 t/hm^2的中产园适宜施钾量为300 kg/hm^2。

【Objectives】The aim was to study responses of pear trees to different K_2 O application rates during the growth periods and accumulation characteristics of K in fruits and leaves in two different output orchards.【Methods】A field experiment was carried out in two 14 year old ‘Huangguan＇ pear orchards in same area.One is high-yield orchard（60–70 t/hm2~） and the other is a medium-yield orchard（30–40 t/hm^2）. Four rates of K_2O（0, 150, 300 and 450 kg/hm^2） were applied in each orchard. Leaves and fruits were sampled at five periods including the young-fruit stage, expanding Ⅰ stage, expanding Ⅱ stage, mature period and a month later after maturation. Effects of increasing K on outputs, fruit quality, K contents and accumulation in fruits and leaves and K use efficiency were explored.【Results】The yields were significantly increased in the high-yield orchard with the increasing of K_2 O application, and the yield under K450 was increased by 16.9 % compared to the control.However, in the medium-yield orchard, the K300 treatment led to the maximum output, and the yield was 27.2 %higher compared to the control. The fruit soluble sugar contents and sugar-acid ratios were enhanced by theincreasing of K_2 O application, while the titrable acid contents were declined. The K contents in fruits and leaves were decreased gradually from the young fruit period to maturation. Anyway, the K contents were increased at different degrees by increasing fertilization rates. The leaf K accumulation amount reached the maximum during the expendingⅠstage, and then decreased slowly. The fruits accumulated the most amount of K during the expanding stage, which accounted for 60%–79% of the K that accumulated in the whole growth period. The fruit K accumulation rate was found to be increased after the expanding period in the high-yield orchard, while it slowed down in the medium-yield orchard. Leaf K was withdrew back to the tree body before leaf senescence, and the reflux degree in the high-yield orchard was higher than that in the medium-yield orchard.The removal of K by fruit harvest and fallen leaves in the high-yield orchard was 258–314 g/plant and was166–192 g/plant in the medium-yield orchard. The K physiology efficiencies（KPE） were 414.0 kg/kg and 405.2kg/kg under K450 in the high-yield orchard and K300 in the medium-yield orchard respectively.【Conclusions】The K application resulted in an increase in K absorption of pear trees, fruit output and quality.The fruit expanding stage was the maximum efficiency period of K absorption and utilization and topdressing. K fertilizer before this period was a practical fertilization way. Taking account of the yield, K physiological efficiency and fruit quality index, we recommended the K_2 O application rate of 450 kg/hm^2 in the high-yield orchard and 300 kg/hm^2 in the medium-yield orchard.