干旱胁迫下喷施14-羟基芸苔素甾醇对冬小麦穗花发育及碳氮代谢的调控

Regulation of spraying 14-hydroxylated brassinosteroid on spike and fertile floret development and carbon and nitrogen metabolism of winter wheat under drought stress

【目的】明确外源芸苔素甾醇类化合物(brassinosteroids,BRs)中14-羟基芸苔素甾醇(14-hydroxylated brassinosteroid,14-HBR)对干旱胁迫下冬小麦穗花发育成粒的调控效果,为小麦大田生产减轻干旱胁迫危害提供技术支撑。【方法】以大穗型品种周麦16(ZM16)和多穗型品种豫麦49-198(YM49-198)为试验材料,试验处理包括中等干旱条件下(0-40 cm土层相对含水量47.38%~61.91%),在小麦拔节后20天设置叶面喷施0.05μmol/L的14-HBR(DBR)和喷施清水对照(DCK);拔节期正常灌水条件下(灌水750 m^(3)/hm^(2))喷清水对照(WCK)。调查两品种小麦幼穗可孕小花发育动态,不同器官干物质积累和碳氮代谢动态,小麦产量及其构成因素。【结果】两品种3个处理的每穗小花数均表现为WCK>DBR>DCK趋势,干旱胁迫下喷施14-HBR与喷施清水相比,能有效降低小花退化和败育,增加可孕小花成粒数,但其效果仍不能完全抵消中等缺水的胁迫效应。喷施14-HBR处理6天后,两品种穗器官和非穗器官干物质重和氮素积累量、穗可溶性糖含量、穗/叶可溶性糖值、穗/非穗器官氮积累量值、穗器官的碳/氮(C/N)值均高于干旱对照处理,而穗/非穗器官干物质值、叶片可溶性糖含量、叶器官C/N值则均低于干旱对照处理。与干旱对照处理相比,两品种的灌水和喷施14-HBR处理均能显著提高穗粒数和产量,穗粒数增幅分别为50.69%和16.04%(ZM 16),38.98%和15.07%(YM 49-198);产量增幅分别为99.44%和28.93%(ZM 16),92.86%和26.86%(YM 49-198);喷施14-HBR处理和干旱对照处理的穗数和千粒重差异不显著。就产量三因子调控效应而言,干旱条件下喷施14-HBR主要是通过提高穗粒数进而增加产量,且对大穗型品种ZM16的增粒增产效果好于多穗型品种YM49-198。【结论】干旱胁迫下在小麦小花退化前外源喷施14-HBR可以促进源器官物质生产,调节穗和叶可溶性糖,穗和非穗器官干物质重及氮素的分配,降低叶的C/N值而增加穗的C/N值,增强糖和氮从叶源器官向穗库器官的转运能力,进而优化穗花发育,提高干旱耐受性。

【Objectives】Clarifying the regulation effect of spraying 14-hydroxylated brassinosteroid(14-HBR)on the development of spike and fertile floret in winter wheat under drought stress.【Methods】A field experiment was conducted with large-spike(Zhoumai16,ZM 16)and multi-spike(Yumai49-198,YM 49-198)wheat cultivars.The three treatments in the study were foliar spraying of 0.05μmol/L of 14-HBR(DBR)or clear water(DCK)under moderate drought stress(i.e.,the relative water content of 0-40 cm soil layer was 47.38%-61.91%.),and spraying of clear water under normal irrigation condition(WCK;the amount of irrigation was 750 m^(3)/hm^(2) during jointing stage).Development of young panicle,dry matter accumulation dynamics,yield and yield components were measured.【Results】Efficient water supply reduced the number of fertile florets and the floret fruit number.The number of florets per panicle of the two cultivars were in the order:WCK>DBR>DCK.Compared to DCK,spraying 14-HBR could not offset the water stress completely,but effectively reduce floret degeneration and abortion,increase the number of fertile florets of the two wheat cultivars.Compared with DCK,DBR increased the dry matter and N accumulation of spike and non-spike organs,soluble sugar content in spike organs,soluble sugar ratio of spike/leaf,N accumulation ratio of spike/non-spike organ,and C/N ratio of spike organs of the two cultivars after 6 days of spraying 14-HBR,but decreased the dry matter ratio of spike/non-spike organ,soluble sugar content of leaf and C/N of leaf.DBR significantly improved grain number per spike(ZM1616.04%and YM49-19815.07%)and yield(ZM1628.93%and YM49-19826.86%).The spike number and 1000-grain weight of DBR and DCK treatments were not significantly different.【Conclusions】Spraying 14-HBR increased yield mainly by improving the grain number per spike,and the effect was better in large-spike cultivar(ZM16)than that in multi-spike cultivar(YM 49-198).Under moderate drought stress,spraying 14-HBR before wheat florets degradation could promote the material production of source organs,regulate the distribution of spike and leaf soluble sugar,spike and non-spike organs dry matter and nitrogen,decrease the leaf C/N value,increase the spike C/N value,and enhance the transport capacity of sugar and nitrogen from source organs to spike sink organs.Thus,spraying of 14-HBR optimized the development of spike and floret and improved drought tolerance.