不同类型钾肥对棉花苗期生长发育和叶片生理特性的影响

在田问试验条件下,研究了单独施用速效钾肥、控释钾肥以及两者配合施用对棉花苗期生长发育和叶片生理特性的影响.结果表明,施用钾肥能够不同程度地提高棉苗的株高、单株叶面积、倒四叶叶面积、单株叶片数和地上部干质量,促进棉苗的生长发育.同时施钾能够促进棉花功能叶片(倒四叶)叶绿素的合成,增强光系统Ⅱ的最大光化学效率(Fv/Fm)、潜在的光化学活性(Fv/Fo)、电子传递速率(ETR)、实际光化学效率(φP Ⅱ),从而提高了功能叶片的光合速率.同时施用钾肥还提高了棉花功能叶片中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)的活性,降低了过氧化物酶(POD)的活性,减少了膜脂过氧化物MDA的产生,有利于延缓功能叶片的衰老.不同类型钾肥处理中,单独施用速效钾肥及速效和控释钾肥的配施均能够促进棉花的生长发育和改善叶片的生理特性,但单独施用控释钾肥的效果并不显著,因此在土壤缺钾较严重条件下单独施用控释钾肥时,配合施用一定的速效钾肥对于促进棉花苗期的生长发育和改善叶片的生理特性具有重要的意义.

Effects of Different Types of Potassium Fertilizer on Growth and Leaf Physiological Characteristics at Seedling Stage of Cotton

Experiment was conducted to study the effects of different types of potassium nutrition on cotton growth and leaf physiological characteristics at seedling stage. Three types of potassium fertilizer, rapid available potassium fertilizer, controlled release potassium fertilizer and the intermix of the two fertilizer, were applied under field condition with randomized block design. The results showed that application of potassium fertilizer increased plant height, leaf numbers per plant, the last fourth leaf area, leaf number and dry weight per plant and promoted the development of cotton at seeding stage. Potassium fertilizer application promoted the synthesize of chlorophyll of last fourth leaf, increased the chlorophyll fluorescence dynamics parameters, Fv/Fm, Fv/Fo, the actual efficiency (φP Ⅱ)and photosynthetic electron transport rate(ETR), which improved the photosynthesis of functionary leaf, in addition,SOD, CAT activity were enhanced, yet POD activity and the content of MDA were weakened,which postponed the consenescence of functionary leaf. At the three types of potassium fertilizer, the application of rapid available potassium fertilizer and the mix of rapid available potassium fertilize and controlled release potassium fertilizer promoted the growth of cotton seedling stage and the leaf physiological characteristics, but the effect of the application of controlled release potassium fertilizer on the growth of cotton seedling stage and the leaf physiological characteristics are indistinctively, so it is important to add some rapid available potassium fertilizer at the soil lacking the potassium severely when the controlled release potassium fertilizer is applied lonely, which would promote the growth of cotton seedling stage and the leaf physiological characteristics effectively.