中文摘要：

【目的】在N、P肥用量固定的2种不同水分条件下,探究K肥施用对甘蔗植株脯氨酸合成积累的效应。【方法】以甘蔗品种粤糖55为研究材料,利用桶栽试验法,在正常水分（土壤含水量〉25%）和干旱胁迫（土壤含水量〈15%）条件下,当尿素和过磷酸钙用量分别为918,1 800kg/hm^2时,测定0,378,750,1 410kg/hm^2钾肥对甘蔗叶片P5CS、δ-OAT活性及游离脯氨酸、叶绿素含量的影响。【结果】当钾肥用量为0-1 410kg/hm^2时,随着钾肥用量的增加,正常水分条件下甘蔗叶片的游离脯氨酸含量和P5CS、δ-OAT活性均呈先下降后升高趋势;干旱胁迫条件下,以上3个指标均呈先升高后下降趋势,且均高于正常水分条件下的相应值。无论是在正常水分还是干旱胁迫条件下,甘蔗叶片叶绿素含量均呈先升后降趋势,但正常水分条件下的叶绿素含量高于干旱胁迫条件。干旱胁迫条件下,当钾肥用量为378kg/hm^2时,甘蔗植株中的P5CS和δ-OAT活性均最强,同时叶片中的游离脯氨酸、叶绿素含量也最大。【结论】干旱胁迫下,钾肥施用量对甘蔗植株游离脯氨酸合成关键酶P5CS、δ-OAT的活性有显著影响,进而影响到植株游离脯氨酸的合成与积累。研究区红壤土最佳的N、P、K肥搭配方案是尿素918kg/hm^2、过磷酸钙1 800kg/hm^2、氯化钾378kg/hm^2。

英文摘要：

[Objective] This paper explored the effects of different potassium （K） fertilization levels on proline biosynthesis and accumulation in sugarcane plants under two water conditions when nitrogen （N） and phosphorus （P） were at fixed levels. [Method] Sugarcane variety YT55 cultivated in bucket was used as plant materials for pod experiment. When the amount of urea and calcium superphosphate were 918 and 1 800 kg/hm^2, the contents of free proline and chlorophyll and the activities of PSCS and δ-OAT were measured at different K fertilizer application rates of 0,378,750, and 1 410 kg/hm^2 under normal （soil moisture 〉25%） and drought （soil moisture 〈15%） stress conditions. [Result] When K fertilization was 0 to 1 410 kg/hm^2, free proline content and activities of P5CS and δ-OAT in normal water condition decreased before increasing as the increase of K fertilization. In drought stress, they all increased and then decreased, and their values were higher than under normal condition. In both conditions, chlorophyll content in sugarcane leaves increased and then dropped, and the values under drought stress condition were higher than under normal condition. Under drought stress condition and when K fertilizer application was 378 kg/hm^2 ,PSCS and δ-OAT had the largest activities and free proline and chlorophyll had the largest con- tents. [Conclusion] K fertilization levels had significant effects on activities of PSCS and δ-OAT so as to the biosynthesis and accumulation of free proline in sugarcane plants. The best usages of N,P, and K fertilizers were urea, calcium superphosphate and potassium chloride with amounts of 918, 1 800, and 378 kg/hm^2 for red soil.