部分根系供磷对黄瓜根系和幼苗生长及根系酸性磷酸酶活性影响

Effects of the Part of P-supply Roots on Cucumber Seedling Growth,P Concentration in Shoot and Root and Secreted Acid Phosphatase Activity by Root

通过分根处理研究了部分根系供磷对黄瓜幼苗生长、植株体内的含磷量及根系酸性磷酸酶活性的影响。结果表明 ,2 0 %根系缺磷 (1条根缺磷 ,4条根供磷 )可以促进根系及植株地上部的生长 ,其根系及地上部的生物量分别是正常生长植株的 1.39倍和 1.2 1倍。2 0 %根系缺磷 ,还可以促进其它供磷根系对磷的吸收。分根处理后 ,2 0 %根系缺磷不影响植物对磷营养的需要 ,但却表现出了R/S比增大的典型缺磷反应 ,说明植物感应缺磷根系起着比地上部更为重要的作用。分根处理后不供磷根系的酸性磷酸酶活性显著高于供磷根系的酸性磷酸酶活性 ,并且根系的酸性磷酸酶活性只与根系的含磷量显著相关 ,与地上部的磷营养状况关系不明显。这说明 ,缺磷条件下 ,黄瓜植株根系分泌酸性磷酸酶活性的增高 ,是黄瓜根系对低磷胁迫的适应性机理 ,而不是地上部改善体内磷营养的调控机理。

The split root technique (Fig.1) was adopted to study the effects of supplying P to 20% or 80% of the roots system on cucumber seedling growth,P concentration in shoot and root and root acid phosphatase activity. The results showed that the placement of 20% roots in P free nutrient solution could increase shoot and root growth,the dry weights of shoot and root increased by 39% and 21% over those of the control ( Figs.2 ,3),and it also could increase root uptake of phosphorus. Placing 20% of root in P free nutrient solution did not decrease the P concentration in shoot (Fig.6),but gave a larger R/S ratio than that of +P treatment (Fig.5),which [HJ6”:2]indicts that response of root to P deficiency stress was earlier than that by shoot. From 2 d after split root treatments,the activity of acid phosphatase secreted by root in P free nutrient was higher than that by root in full nutrient solution (Fig.7),and the activity acid phosphatase secreted by root was significant correlated to P concentration in root (Fig.8),but not to P concentration in shoot. So we could say that the acid phosphatase secreted by root was a response of it to P deficiency stress,but not the regulation P deficiency stress by shoot.