NaCl胁迫对苜蓿和羊草苗期生长及养分吸收的影响

通过模拟试验研究了NaCl胁迫对苜蓿和羊草苗期生长及养分吸收的影响。结果表明 ,NaCl胁迫对苜蓿生长及养分吸收的影响明显高于羊草。在稳定供水条件下 ,羊草生长的临界土壤溶液NaCl浓度为 2.54mmol/L ,临界土壤总盐量为 0.59% ;苜蓿生长的临界土壤溶液NaCl浓度为 130mmol/L ,临界土壤总盐量为 0.35%。苜蓿的光合能力受盐胁迫的影响比羊草大 ,尤其是日最大净光合速率随盐度水平的增加明显降低。随土壤含盐量的增加 ,苜蓿和羊草植株N、P含有率变化较小 ,但积累量显著减少 ;K的比吸收率显著降低 ,植株K含量减少 ;植株Na的SAR随土壤盐分增加显著提高 ,Na含量不断积累增加 ,植株K/Na降低

Effect of NaCl stress ongrowth and nutrient absorption in seedling of Medicago s ativa and Leymus Chinesis

Medicago sativa and Leymus Chinesis were expos ed to differentcontent of NaCl (26 mmol/L(T0), 125mmol/L(T1), 216mmol/L(T2), 30 8 mmol/L(T3)) in a controlled pot culture system for 30 days. Growth reduction b y salt-stressed was significantly greater in Medicago sativa than in Leym us Chinesis and Leymus Chinesis represented a higher salt resistance than Medicago sativa . The salinity critical values of NaCl concentration in soil were 130mmol/L f o r Medicago sativa , and 254 mmol/L for Leymus Chinesis. In total salt c onten t the values were 0.35% and 0.59%, respectively. The effect of salt stress on ne t photosynthesis rate (NPn) was more distinct in Medicago sativa than in L eymus Chinesis. Salt stress decreased the content of K, but did not affect t he contents of N and P. Comparison with Leymus Chinesis, Medicago sativa sh ow ed a lower specific absorption rate (SAR) of K, but a higher SAR of Na.