NaCl胁迫对四种禾本科牧草种子萌发的影响

Effects of NaCl stress on seed germination and seedling growth of four Poaceae grass species

研究了4种多年生根茎型耐旱植物——羊草、高冰草、苇状羊茅和俄罗斯新麦草种子的萌发和根芽生长对不同浓度(0、50、100、150、200、300、400和500mmol.L-1)NaCl胁迫的响应。结果表明,4种牧草种子的发芽率随着盐浓度的增加呈下降趋势。其中,羊草种子耐盐性最差,300mmol.L-1NaCl处理的种子发芽率仅为1.5%,浓度超过300mmol.L-1时,没有种子萌发;高冰草、苇状羊茅和俄罗斯新麦草耐盐性较强,在500mmol.L-1NaCl时发芽率分别为17.3%、20.0%和18.1%。4种牧草的根长和芽长均与NaCl浓度呈极显著的负相关,但表现不同:随着NaCl浓度的增加,俄罗斯新麦草的根长下降速率最快,高冰草最慢;羊草芽长下降速率最快,高冰草最慢;羊草的根/冠比值呈上升趋势,而其他3种牧草则呈下降趋势。说明NaCl胁迫对羊草抑制表现为胚根<胚芽,而后三者则为胚根>胚芽。从种子发芽率和胚生长状况看,在种子萌发期内,羊草种子萌发和苗期的耐盐能力最差,而高冰草、苇状羊茅和俄罗斯新麦草的种子萌发和苗期生长均有较强的耐盐能力。

This paper studied the seed germination and seedling growth of four perennial droughttolerant rhizome grasses Leymus chinensis, Agropygron elongatum, Festuca arundinacea and Elymus junceus under effects of 0, 50, 100, 150,200,300,400, and 500 mmol NaCl·L^-1. With increasing NaCl concentration, the seed germination rate of test grasses had a decreasing trend. L. chinensis had the lowest salt tolerance. Its seed germination rate was only 1.5% at 300 mmol NaCl·L^-1, and no seeds germinated at 〉 300 mmol NaCl·L^-1. A. elongatum, F. arundinacea and E. junceas had higher salt tolerance. Their seed germination rate reached 17.3%, 20%, and 18.1%, respectively, at 500 mmol NaCl·L^-1. The root length and shoot height of test grasses were significantly negatively correlated with NaCl concentration. With the increase of NaCl concentration, E. junceus had the greatest decrement of its root length while A. elongatum had the smallest one, and L. chinensis had the greatest decrement of its shoot length while A. elongatum had the smallest one. The root/shoot ratio of L. chinensis increased while that of the other three grasses decreased with increasing NaCl concentration, illustrating that for L. chinensis, the inhibitory effect of NaCl was stronger on root growth than on shoot growth, while for the other three grasses, it was in adverse. In sum, L. chinensis had the lowest salt tolerance during its germination and seedling stages, while the other three grasses had higher salt tolerance in their seed germination and seedling growth.