钙磷对紫花苜蓿根瘤菌体系酸铝胁迫的修复效应

Remediating Effect of Ca^(2+) and P on Growth and Nodulation of Alfalfa-Rhizobium After Acidity and Aluminum Stresses

为初步探究钙、磷在酸铝胁迫之后对豆科植物及其根瘤菌共生结瘤的修复效应,本试验采用水培培养法,以紫花苜蓿和耐酸苜蓿根瘤菌91522为材料,探讨了钙磷对酸铝胁迫后苜蓿根瘤菌生长、存活及苜蓿结瘤、初生根伸长的影响.结果显示,5mmol/L Ca2+能够显著提高酸铝胁迫下耐酸根瘤菌的生长和存活,4μmol/L P素在Ca2+的基础上进一步提高根瘤菌存活率.在钙、磷共同存在的条件下,苜蓿初生根的伸长量比酸铝胁迫对照提高了5～7倍;在铝毒害之后,通过补充Ca2+和P,苜蓿结瘤数、瘤鲜重、现瘤时间、农艺性状得到了显著的恢复;高浓度(10mmol/L)Ca2+对苜蓿根瘤菌生长有更好效果,但对苜蓿结瘤效果则不如5mmol/L Ca2+.初步认为,钙磷可以通过提高根瘤菌在酸性环境下的存活、苜蓿根系生长以及参与根瘤菌与豆科宿主识别过程来恢复酸铝毒害后的苜蓿-根瘤菌共生结瘤过程.

Alfalfa and its acid-tolerant rhizobium strain 91522 were used as materials in a water culture ex periment to study the effects of calcium and phosphorus on the growth and nodulation of the alfalfa-rhizo- bium system under acidity and aluminum stresses. The research showed that 5 mmol/L Ca2＋ significantly improved the growth and survival of rhizobium compared with the control and that under the same Ca2＋ level the addition of 4 μmol/L P further enhanced rhizobium survival rate. By combining Ca2＋ and P, the elongation of alfalfa primary root was raised by 5--7 times over that of the control under the acidity @ alu- minum stress condition. When Ca2＋ and P were added in combination, the nodular number, nodule fresh weight, with th time of nodule occurrence and agronomic t e treatment 5 mmol/L Ca2＋ , 10 mmol/L C ralt a2＋ s of alfalfa were satisfactorily recovered. Compared had better effect of improving nodule growth of al falfa but poorer effect on nodulation. It was tentatively concluded that Ca2＋ and P could recover the symbi osis nodular process after alfalfa suffered from acidity and A1 toxicity, by improving rhizobium survival and root growth and by participating in the identification process between the legume host and its rhizobi- um strain.