棉花苗期生长发育对土壤速效钾水平的响应

Response of cotton seedling growth and development to soil available potassium levels

【目的】研究棉花苗期主要生长发育性状对土壤速效钾水平的响应,为筛选棉田土壤速效钾评价指标提供依据。【方法】以中棉所100为供试品种,采用长0.8 m、宽0.58 m、深0.44 m的塑料箱,每箱装土240 kg,通过添加钾肥设置68.1、77.4、93.3、104.2、122.9、130.9、142.4和171.1 mg/kg 8个速效钾水平土壤处理(分别以K_(1)、K_(2)、K_(3)、K_(4)、K_(5)、K_(6)、K_(7)和K_(8)表示)。在棉花一叶期、三叶期、五叶期、七叶期和现蕾期5个时期取样,测定棉株农艺性状、干物重、全钾含量、光合指标等。【结果】棉花一叶期,不同土壤速效钾水平间棉花株高、茎粗无显著差异;三叶期、五叶期、七叶期和现蕾期,棉花株高和茎粗均呈随土壤速效钾水平提高而增加的趋势;土壤速效钾分别达到K_(4)和K_(5)处理水平时,棉花株高和茎粗基本趋于稳定。K_(5)处理及以上处理的叶面积、干物重显著高于其他处理,但这些处理之间无显著差异。蕾期各处理棉株功能叶片的E、Ci、Gs、SPAD等值对土壤钾水平无显著响应。K_(7)处理Pn显著优于K_(2)与K_(3)处理。【结论】当土壤速效钾水平高于123 mg/kg时,可促进棉株苗期养分吸收和干物质积累,促进棉株茎秆生长,叶面积增大,使棉花苗期的生长发育进程加快,有利于棉花从营养生长向生殖生长转化。

【Objective】This study aims to investigate response of the main growth and development traits of cotton seedlings to soil available potassium levels in order to provide a basis for formulating evaluation indicators of soil available potassium in cotton fields.【Methods】The variety 100 of the Institute of Cotton Research was used as the experimental material,plastic boxes with a length of 0.8 m,a width of 0.58 m,and a depth of 0.44 m were used,each box containing 240 kg of soil.Eight available potassium levels of soil were set by adding potassium fertilizer,including 68.1,77.4,93.3,104.2,122.9,130.9,142.4,and 171.1 mg/kg(represented by K_(1),K_(2),K_(3),K_(4),K_(5),K_(6),K_(7),and K_(8),respectively).Sampling was conducted at 5 times during the cotton 1 leaf stage,3 leaf stage,5 leaf stage,7 leaf stage,and bud stage to determine the agronomic traits,dry matter weight,total potassium content,and photosynthetic indicators of the cotton plant.【Results】During the first leaf stage,there was no significant difference in cotton plant height and stem diameter among different soil available potassium levels;During the 3-leaf stage,5-leaf stage,7-leaf stage,and budding stages,the plant height and stem diameter of cotton showed an increasing trend with the increase of soil available potassium levels;When the soil available potassium reached the levels of K 4 and K 5,the cotton plant height and stem diameter tended to stabilize.The leaf area and dry matter weight of treatments with K_(5)and above were significantly higher than those of other treatments,but there was no significant difference between these treatments.At the bud stage,the E,Ci,Gs,SPAD values of functional leaves of cotton plants in each treatment showed no significant response to soil potassium levels.In terms of Pn,K 7 was significantly superior to K_(2)and K_(3).【Conclusion】When the soil available potassium level is higher than 123 mg/kg,it can promote the nutrient absorption and dry matter accumulation of cotton seedlings,promote the growth of cotton stems,increase leaf area,accelerate the growth and development process of cotton seedlings,and facilitate the transformation of cotton from nutritional growth to reproductive growth.