Studies On Physiological Regulation Role Of Water Retaining Slowiy-release Fertilizer And Melatonin In Salt Tolerance Of Rice Seedlings

In recent years,due to the strong expansion of the scope and intensity of human activities,it leads to serious decline in soil quality,such as soil salinization,which seriously damages the survival of human ecology Environment and the maintenance of human livelihood of the cultivated land.Soil salinization has led to a serious decline in soil quality and a serious shortage of soil productivity.In response to this situation,the research workers have been exploring to improve soil salinization of soil fertility of the scientific method.In order to explore the regulation effect of new materials on soil salinization,this study selected a new type of slow-release fertilizer(the following abbreviation to as matrix fertilizer)and melatonin as materials to study the regulation effects of two materials on rice growth under salt stress,The main results were as follows:1.The application of matrix fertilizer under low salt stress(soil salinity:0.268%)and high salt stress(soil salinity:0.468%)could improve the growth of rice seedlings,and mainly reflected in:The changes of the morphological characteristics and root morphology of rice seedlings.At 20 days and 40 days of culture,the more ratio of matrix fertilizer,the more growth of rice under low salt treatment and high salt treatment.The total root length,root volume,root surface area and root tip number showed obvious increase in varing degrees.The rice seedlings growth was still obvious increased under low salt treatment for 80 d applied with matrix fertilizer,especially 4%matrix fertilizer treatment.After 60 days of high salt treatment,all the rice seedlings died.The changes of rice biomass and leaf parameters.Under low salt stress,the biomass,the maximum leaf length and the chlorophyll showed a significant increase with the increase of the ratio of matrix fertilizer and the time of culture.The leaf temperature was decreased.The leaf length and leaf chlorophyll content in the shoots and root biomass were significantly increased by 20 d,2%and 4%matrix fertilizers under high salt stress.Under salt stress,nitrogen(N),phosphorus(P)and potassium(K)in the shoots and roots of rice seedlings were increased with the increase of the ratio of matrix fertilizer.The application of matrix fertilizer significantly reduced the Na content in rice.Under low salt stress,Na+transport coefficient increased with the increase of matrix fertilizer ratio.The changes of photosynthetic parameters of rice seedlings under low salt stress were the best when the rice seedlings were cultured for 80 days.With the increase of the ratio of matrix fertilizer,the changes of the parameters showed different trends,the Pn,Gs,Ci,Tr and WUE were significantly increased and Ls shows significantly decreased when the ratio of matrix fertilizer was 4%.The change of antioxidant enzyme activity.Under low salt stress,all antioxidant enzyme activities showed different changes.With the increase of the ratio of matrix fertilizer,superoxide dismutase(SOD),catalase(CAT),ascorbate peroxidase(APX)and other enzyme activities were increased,especially at the 4%matrix fertilizer,and peroxidase(POD)showed a significant decrease.2.The rice experiments were carried out in hydroponic culture and foliage spraying melatonin(MT).The results were as follows:Under salt stress,the growth of rice seedlings were seriously inhibited,and the salt stress of rice was very serious and could not survive under 150 mM NaCl.The effect of MT was enlarged at 75 mM NaCl.Spraying MT could effectively alleviate salt stress and promote the growth of rice seedlings.With the increase of MT concentration,the plant height,biomass and mineral ion selective absorption of rice seedlings were getting better.The effect was the most significant when MT concentration was 200 μM.In addition,the Na+ uptake of aboveground and root were decreased significantly applied with MT.According to the preliminary test results that we could know the 200 μM MT has the best effection.Thus,we choose 200 μM MT for the next research.Under 75 mM NaCl stress,spraying 200 μM MT could significantly increase the aboveground biomass of rice seedlings,but did not change the effect of root biomass.The relative water content of leaves of rice seedlings was significantly increased,and the relative conductivity was decreased applied with MT.The results showed that the spraying of 200μM MT promoted the increase of N,P and K contents in shoots and roots of rice seedlings.Under salt stress,spraying MT significantly reduced the uptake of Na+ in the shoots of rice seedlings and decreased the transport coefficient of Na+,the MT promoted the selective absorption of K and Na,and promoted the transport of K+.MT also affected the activity of antioxidant enzymes of rice seedlings,significantly enhanced the activities of SOD,CAT and APX.In addition,spraying MT also enhanced the photosynthesis of rice leaves.