混合盐碱胁迫对桑树种子萌发和根系生长的影响

Effects of mixed salt and alkali stress on germination and root growth of mulberry seeds

将两种中性盐(Na Cl和Na2SO4)、两种碱性盐(Na HCO3和Na2CO3)按不同比例混合,模拟出16种盐度和碱度不同的盐碱条件,并对桑树种子萌发过程进行混合盐碱处理,测定桑树种子发芽率、发芽指数和发芽势等种子萌发参数,以及萌发中根系长度和活力指数等根系生长参考,通过模糊数学隶属函数值的方法分析了各参数与各种致胁变因素之间的相关关系。结果表明:在复杂的盐碱混合胁迫下,影响桑树种子萌发和根系生长的致胁变因素主要是盐度、p H和缓冲量。盐度是桑树种子萌发过程中的主导因素,碱胁迫的影响较小;而碱胁迫(p H值)主要抑制桑树种子萌发过程中根系生长和活力指数,尤其是p H大于8.0时,桑树幼根褐化、变软,根系生长主要受p H值和缓冲量等碱性条件的制约。因此,盐胁迫限制了桑树种子发芽,碱胁迫抑制了萌发中根系生长。这是松嫩平原盐碱土制约植被恢复的重要限制因素之一。

During germination, seeds of mulberry were treated with 16 different of alkalinity and salinity conditions, which were established by mixing NaC1, NaHCO3, Na2SO4, and Na2CO3 at various proportions. Germination parameters （germination rate, germination index and germination energy etc.） and root growth parameters （root length, vigor index etc.） were investigated. The correlations of indexes and stress-caused factors during mulberry seeds germination were analyzed by using method of subordinate function value. The results show that salinity, pH, buffer capacity were the dominant stress acting factors in all of stress indexes during mulberry seed germination and root growth under complex saline and alkali conditions; Salinity was the leading factor on the germination of mulberry seeds than alkali stress, but root length and vigor index were inhibited more seriously by alkali stress than salt stress; While alkaline stress （pH value） mainly inhibited the root growth during germination and vigour index of Mulberry seeds, Mulberry root became darkened and soft when pH was over 8, so root growth was mainly inhibited by pH and buffer capacity. It was found that the germination of mulberry seeds was inhibited by salinity, and the root growth were limited by alkali stress. These stress were one of the most important limiting factors of vegetation recovery in Songnen Plain, Northeast China.