外源Ca2+和IBA对NaCl胁迫下能源植物杂交狼尾草幼苗生长的影响

以能源植物杂交狼尾草(Pennisetum americanum×P.purpureum)为实验材料,在NaCl胁迫条件下用外源IBA(100 mg/L),CaCl_2(浓度分别为0、1、2、5 mmol/L)处理杂交狼尾草幼苗,处理3周后测定植物的存活率、鲜重、干重、株高、生根数和地上部分、地下部分的离子含量。结果表明,经过IBA溶液预处理的杂交狼尾草幼苗的存活率、鲜重、干重、株高、生根数明显高于未处理的幼苗;在NaCl胁迫下,随着外源Ca~(2+)浓度的升高,杂交狼尾草幼苗的存活率、鲜重、干重、株高、生根数以及Ca~(2+)含量都明显升高并在CaCl_2浓度为2 mmol/L时达到最大值;随着外源Ca~(2+)浓度的升高,Na~+含量、Na~+/K~+降低,当CaCl_2的浓度为2mmol/L时,Na~+含量、Na~+/K~+最低。以上结果表明外源Ca~(2+)和IBA对NaCl胁迫下杂交狼尾草幼苗生长有促进作用,可以缓解NaCl胁迫对杂交狼尾草幼苗生长的抑制作用,提高杂交狼尾草幼苗在NaCl胁迫下的成活率;缓解盐害的最适的Ca~(2+)浓度为2mmol/L。

Effects of exogenous Ca2+ and IBA on seedlings growth of energy plant hybrid Pennisetum under NaCl stress

More than 6% of the world''s total land area is impacted by salt. Most cultivated plants are sensitive to salt stress, which triggers ionic disturbance and has osmotic and toxic effects due to high cellular Na⁺ concentrations, which ultimately greatly reduces vegetative growth. Calcium is an indispensable nutrient for plant growth and development, and it also plays important role in plant response to abiotic stresses. Calcium deficiency phenomenon is universal in Chinese arable land and its shortage in salinized land is more intense and severely limits the growth of crops. Addition of Ca²⁺ could reduce the growth inhibition induced by salt stress by increasing Na⁺/K⁺ ratios, maintaining normal metabolism, stabilizing the cell membranes, and balancing absorbed ions. Hence, the liberal application of Ca²⁺ fertilizers is the recommended treatment for enhancing soil Ca²⁺ availability, stimulating plant yield, and preventing further deterioration of saline land. Indoyl-3-butyric acid(IBA) is a safe and efficient plant growth regulator, which is mainly used to promote rooting and root development. IBA, as an important plant hormone, participates in plant growth and development. Studies showed that IBA treatment can increase root growth and survival rate of plants under salt stress. A hybrid Pennisetum(Pennisetum americanum× P.purpureum) is now widely regarded to have substantial potential as a bioenergy plant and a forage source for livestock production. It has been characterized as having good stress resistance, fast growth, and high yield. Coastal areas are considered to be ideal sites for cultivation of energy plants since they are occupy large areas and usually cannot be used as farmland due to high soil salinity. Hence, the hybrid Pennisetum is an ideal crop for this type of land. Therefore, in order to better guide the bio-transformation of saline lands using this potential energy plant, the effects of exogenous Ca²⁺ and IBA on the growth of seedlings of energy plant hybrid Pennisetum were examined under saline conditions. In a pot experiment, we investigated the effects of exogenous Ca²⁺ and IBA on the survival rate, fresh weight, dry weight, plant height, root number, and ion content in the hybrid Pennisetum seedlings under NaCl treatment. The results indicated that the survival rate, fresh weight, dry weight, plant height, and root number of hybrid Pennisetum seedlings pre-treated with IBA were significantly higher than those in untreated, control plants. Under NaCl stress, the survival rate, fresh weight, dry weight, plant height, root number, and Ca²⁺content in hybrid Pennisetum seedlings significantly increased with increasing Ca²⁺ content; the maximum effect was observed in treatment with 2 mmol/L Ca²⁺. The content of Na⁺ and Na⁺/K⁺ ratio decreased with increasing Ca²⁺ content reaching the maximum effect at 2 mmol/L Ca²⁺. The results showed that exogenous Ca²⁺ and IBA promoted the growth of the hybrid Pennisetum seedlings under NaCl stress, relieved the NaCl stress on the hybrid Pennisetum, and increased the survival rate and salt tolerance of the hybrid Pennisetum seedlings at the optimum content of 2 mmol/L Ca²⁺. These findings provide a theoretical basis for practical application of IBA and Ca²⁺ fertilizers when large-scale cultivation of hybrid Pennisetum occurs on saline land.