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为阐明外源激素和蔗糖调控冬小麦穗粒数和粒重的机理，以冬小麦农大211为材料，设置不同浓度蔗糖和激素，通过离体穗培养及盆栽不同水分条件下喷施激素处理，考察了冬小麦穗粒数、穗粒重、千粒重以及穗部糖含量对外源蔗糖和激素的响应。离体穗培养试验表明，蔗糖浓度为40 g·L^-1，IAA、GA、6-BA和ABA浓度分别为10^-4 mol·L^-1、10^-5 mol·L^-1、10^-5 mol·L^-1和10^-6 mol·L^-1时取得了较高的穗粒数，且穗粒数以穗上部强势粒数与穗中部弱势粒数增幅较大；适当增加培养基GA和ABA浓度也能提高粒重，从而提升穗粒重。盆栽试验表明，与水分适宜处理相比，干旱使成熟期穗粒数、穗粒重和单株生物量显著下降，千粒重无显著变化，干旱处理的幼穗中CTK和ABA含量显著增加。干旱条件下，喷施IAA较其对照显著增加了穗粒重和单株生物量以及幼穗中可溶性糖和IAA含量，显著降低了幼穗ABA含量；喷施GA较其对照显著增加了单株生物量和幼穗GA含量，显著降低了幼穗ABA含量；喷施6-BA较其对照显著增加了单株生物量和幼穗CTK含量，显著降低了幼穗可溶性糖和ABA含量；喷施ABA较其对照显著增加了穗粒重和单株生物量，显著降低了幼穗蔗糖和可溶性糖含量。水分适宜条件下，喷施IAA较其对照显著降低了穗粒数、穗粒重和单株生物量，但显著增加了千粒重和幼穗可溶性糖、CTK和ABA含量；喷施GA较其对照显著增加了幼穗可溶性糖、GA、CTK和ABA含量，但显著降低了幼穗蔗糖含量；喷施6-BA较其对照显著增加了幼穗可溶性糖、CTK和ABA含量；喷施ABA较其对照显著降低了穗粒数，显著增加了幼穗可溶性糖、IAA、CTK和ABA含量。总之，外源蔗糖与激素对冬小麦穗粒数、穗粒重和千粒重都有显著影响，适宜蔗糖和激素处理提高穗粒数，主要由于增加了穗上部强势粒和穗中部弱势粒数。外源喷施激素可缓解干旱胁迫对冬小麦穗粒数和穗粒重的影响，以喷施IAA效果最好，主要通过调控幼穗糖含量和激素含量来调控穗粒数和粒重。

英文摘要:

To elucidate the mechanism of exogenous hormone and sucrose in regulating grain number per spike and grain weight of winter wheat,a winter wheat cultivar,ND211,was selected to test its response of grain number per spike,grain weight and sugar concentration of spike to exogenous sucrose and hormone regulation. The detached-ear culture experiment showed that higher grain number per spike was obtained when sucrose concentration was 40 g·L^-1,and IAA,GA,6-BA and ABA concentrations were 10^-4 mol·L^-1,10^-5 mol·L^-1,10^-5 mol·L^-1 and 10^-6 mol·L^-1,respectively,with the increase mainly occurring at superior grain number in the upper spike and inferior grain number in the middle spike.Appropriate increase of GA and ABA concentration in the medium could also increased grain weight,and thus improved grain weight per spike. Pot experiment showed that the grain number per spike,grain weight per spike and biomass decreased significantly at maturity after drought,but the 1 000-grain weight did not change significantly. CTK and ABA contents of young spike increased significantly during drought. Under drought conditions,as compared with water spraying control,spraying IAA significantly increased grain weight and biomass,soluble sugar and IAA contents of young spike,but significantly decreased ABA content of young spike; spraying GA significantly increased biomass and GA content in young spike,but significantly decreased ABA content in young spike; spraying 6-BA significantly increased biomass and CTK content of young spike,but significantly decreased soluble sugar and ABA content of young spike; spraying ABA significantly increased grain weight and biomass,but significantly decreased sucrose and soluble sugar contents in young spike. Under suitable water conditions,as compared with water spraying control,spraying IAA significantly decreased grain number per spike,grain weight per spike and biomass,but significantly increased 1 000-grain weight and contents of soluble sugar,CTK and ABA in young spike; spraying GA significantly increased soluble sugar,GA,CTK and ABA contents in young spike,but significantly decreased sucrose content in young spike; spraying 6-BA significantly increased the contents of soluble sugar,CTK and ABA in young spike; spraying ABA significantly decreased grain number per spike,but significantly increased soluble sugar,IAA,CTK and ABA contents in young spike. In conclusion,exogenous sucrose and hormone had significant effects on grain number,grain weight per spike and 1 000-grain weight. Suitable sucrose and hormone treatment increased grain number per spike mainly through increasing superior grain number in the upper spike and inferior grain number in the middle spike. Exogenous hormone spraying can alleviate the effects of drought stress on grain number and grain weight per spike,and IAA spraying has the best effect,mainly attributed to its regulation on the content of sugar and hormone in the young spike.

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