The Effect Of Foliar Leaching On Mineral Nutrition Of Plant Under NaCl Stress

Under solution cultivation condition in greenhouse, maize, wheat and soybean were used to study the effect of NaCl stress on plant growth and mineral nutrition balance, as well as genotype difference, approach the mechanism of salt-tolerance, investigate the effect of foliar leaching solution of different pH on alleviating plant salt stress and increasing plant growth. The results were as following:1. Generally the biomass of wheat and maize decrease with NaCl stress. The shoot biomass of wheat decreases less than that of root. The relative salt-tolerance of wheat varieties under different NaCl stress is not accordance. The shoot biornass of maize decreases greater than that of root. The results of maize are reverse. The tolerance of two varieties to low NaCl stress is very strong.2. The Na and K concentrations in shoot of wheat and maize are higher than that of in root. Na concentrations in shoot of wheat increases more than these in shoot as the NaCl stress develops. The shoot Na concentrations of salt-tolerance varieties of wheat and maize are lower than that of salt-sensitive varieties, and the K concentrations are higher. The shoot Na concentrations of the two crops are highly negatively correlated with the growth.3. The K+/Na+ ratios of the shoot and root of the two crops decrease with the increasing of NaCl stress. The K+/Na+ ratio and SK+.Na+s in shoot are higher than these in root and the SK+.Na+s of salt-tolerance varieties are higher than these of salt-sensitive varieties.4. Comparing with the control, the shoot Ca concentrations of wheat decrease under low NaCl concentrations and increase under high NaCl concentrations. The root Ca of wheat and shoot and root Ca concentrationsof maize increase with the increasing of NaCl stress. The shoot Ca concentrations of two crops are higher than that in root. The Na+/Ca+2 ratios of the two crops increase with the NaCl stress and these show that Na/Ca ratios can response to the salt-tolerance of plant better than these of Ca concentrations. The shoot Mg concentration of the two crops keeps unchanged among different NaCl stress treatments and the root Mg concentration decreases with the increasing of NaCl stress.5. The N concentrations in different part of maize increase or keep steady under NaCl stress. The P concentrations in different part of maize increase violently in NaCl stress. The P concentrations decrease with the increasing of the leafage.6. The effects of foliar leaching on growth of plants under NaCl stress differ with the plant categories and varieties. Foliar leaching decreases the Na concentrations in most varieties of wheat and soybean under NaCl stress.7. Foliar leaching advances the growth of salt-sensitive maize variety under high NaCl stress, i.e. it alleviates the salt stress; reduces the shoot K concentrations under high NaCl stress. Foliar leaching of acid solution decreases the Na concentrations of plant under high NaCl stress. Foliar leaching does not affect the Ca and Mg concentrations of the plants under NaCl stress. There is no significant difference of relative water contents of plants among different leaching solutions.8. The mineral nutrition concentrations of shoot leachate increase with the growth and are higher in no NaCl treatments than in NaCl treatments. Acid leaching solution increases the NO3--N, NH4+-N, total N, Mg and Zn concentrations, decreases the Na concentration and has no effect on organic N, K and Ca concentrations of leachate. Taking the difference of the shoot biomass into account, the relative concentrations of Na, Ca and Zn in NaCl treatments are higher than in no NaCl treatments but K concentrations are lower and Mg concentrations have no change.