Mitigative Effects Of Seawater Stress On Aloe Vera By Phosphorus And Its Mechanism

Long coasting extended around our country, and there were 10 million hektare stubble fields in which usable salina at seashore were up to 2 million hektare stubble fields. Thereby development of seawater irrigation agriculture were efficacious measure to solve problems of too large population and lack of plantation and freshwater. On the other hand, it could initiate new scopes on sustaining use of natural resource by growing plant with marked economic benefits and salt tolerance under seawater irrigation in tideland. Aloe vera, a member of the Liliaceae plant family which coming from Africa or mediterranean sea area has prominent economic benefits involved in hairdressing, view and admire, edibility and officinal effects. Therefore, Aloe vera was used as experimental materials to study the effects of exogenous P on frond growth, osmotica accumulation, nutient contents and active components in plant subjected to seawater stress by physiological and biochemical analysis and X-ray electron probe microanalysis. The results obtained were listed as follows.Exogenous P application(SHP)significantly promoted growth and development of aloe seedlings under 30% seawater stress. High P treatments(SHP)markedly promoted leaf elongation rate, significantly increased plant dry weight, water content, chlorophyll content and root vigor, decreased the R/S ratio and electrolytic leakage of leaves distinctly.High P treatments(SHP)significantly increased free amino acid and organic acid contents in aloe leaves, decreased Na~+ and Cl~- contents in roots, promoted K~+ and Ca~2+ transport form root to leaves, and maintained high K~+/ Na~+, Ca~2+/ Na~+, Sk, Na of leaves. At the same time, X-ray electron probe microanalysis results showed that: exogenous P application(SHP) distinctly decreased relative amount of Na+, Cl' in roots, increased relative amount of K+, Ca2+ in fascicular cells of roots and relative amount of K+, Ca2+ in leaves of aloe under 30% seawater stress.30% seawater stress markedly reduced N, P, K contents in leaves of 1 yeared aloe. Under 30% seawater stress, P application of 90 mg P2O5 Kg~-1 significantly enhanced dryweights, water content, AP and P content in leaves, K content in root and and significantly improved transport of N from roots to leaves. At the same time, P application of 150 mg P2O5 Kg~-1 significantly improved AP and soluble sugar content in 1 yeared aloe, but decreased its dry weight and water content obviously.Consequently, exogenous P application(SHP) significantly improved aloe seawater tolerance, moreover the regulation on ions absorption and distribution might be attributed to the mitigative effects of seawater injury on aloe. At the same time, P application markedly enhanced aloe seawater tolerance by improving its nutrition condition. And P3 (90 mg P2O5Kg~-1) level was optimal quantity of exogenous P application on 1 yeared aloe under 30% seawater stress.