Preliminary Study On High-yielding Cultivation Of Sesbania Cannabina In Saline Soil

The area of soil salinization is expanding year by year,and the degree of salinization is becoming more and more serious.It has become a major abiotic stress factor affecting ecological environment safety and agricultural production.Sesbania cannabina is one of the pioneer crops in saline-alkali land management because of its good ability to improve saline-alkali land.The experiments were conducted respectively at the Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education(32°30’N,119°43’E),Yangzhou,Jiangsu Province,China and Coastal Forest Farm of Dafeng,Dafeng town(33°20’N,120°47’E),Yancheng City,Jiangsu Province,China from 2016 to 2017.The Dafeng test site is a beech forest,the beeches have been planted for 3 years.Experimental field had loamy soil,with a textural class of clay loam and the initial fertility status of N=0.72 g kg-1,P=1.45 mg kg-1,K=279 mg kg-1,organic matter of 19.75 g kg-1,pH of 8.8 and salt content of 1.68 g kg-1.In this study,the effects of exogenous gibberellin(0,70,140,210 mg/L),planting density(120000 and 200000 plant/hm2)and nitrogen rate(0,180 and 360 kg/hm2)on germination,seedling growth,yield and yield components of Sesbania cannabina were studied under salinity stress(0,70,140,210 mM and moderate saline land).The main results were as follows.1.Effects of Salinity and Gibberellin on Germination and Seedling Growth of Sesbania cannabinaThe decrease of water uptake,water uptake percentage,water uptake rate,germination rate,germination index,shoot and root length,ratio of root to shoot and MDA level were aggravated with increased salt concentration.At the 210 mM NaCl level,the germination percentage.germination rate,germination index,shoot and root length,and ratio of root to shoot were decreased by 14.4%,71.6%,61%,55%,78.4%and 51.6%respectively.Germination percentage and alpha-amylase were slightly improved at low level of salt stress(70 mM),but significantly inhibited at high(140 mM)and severe(210 mM)salinity.On the contrary,GA3(especially at 140 mg/L)improved germination,seedling growth and alpha-amylase activity,decreased MDA level under each salinity level.At the 7th day after germination,at 140 mg/L GA3 level,MDA content decreased by 22.2%,whereas the alpha-amylase activity increased by 59.7%.Moreover,the enhanced effect of GA3 was more prominent at low salinity condition.2.Effects of Presoaking with GA3 on Growth and Yield of Sesbania cannabina Grown in Saline SoilGibberellin application promoted the growth and yield of Sesbania cannabina.As compared with the control treatment,height,root length,SPAD readings,the contents of starch,soluble sugar and soluble protein,the activities of SOD,CAT and POD,total biomass,pod number per plant,seed number per pod and seed yield were significantly higher in the GA3 treatments.With the increase of GA3 level,these parameters were first increased and then decreased while sucrose content was first decreased then increased.At 140 mg/L GA3 level,pod number per plant,seed number per pod and total yield increased by 40.4%,59.1%and 115.5%.However,the application of GA3 had no observable effects on 1000-seed weight.3.Effects of Density and Nitrogen Rate on Growth and Physiological Traits and Yield of Sesbania Cannabina Grown in Saline SoilExcept for dry matter,relative growth rate(RGR),N uptake and total seed yield,the comprehensive traits of Sesbania Cannabina at low plant density level were better than those at high density level,but density had no significant effects on the activities of antioxidant enzymes.180 kg N/hm2 increased significantly height of Sesbania cnnabina,but had no significant effects on root length.At 120000 plant/hm2 level,180 kg N/hm2 significantly increased the content of chlorophyll and soluble protein as well as N uptake,enhanced photosynthesis and promoted the accumulation of photosynthetic products,finally increased the biomass and seed yield;increased the activities of SOD,CAT and POD and hence,enhanced the resistance of Sesbania Cannabina.At 200000 plant/hm2 level,the best performances of traits were observed at 360 kg N/hm2level.Density and nitrogen rate had no significant effects on 1000-seed weight.In all treatments,the best performances of comprehensive traits of individual plant were observed at the combine of 120000 plant/hm2 and 180 kg N/hm2 level,pod number per plant and seed number per pod increased by 44.7%and 19.3%.However,the maximum total seed yield and characteristics of Sesbania Cannabina populations were reached at the combine of 200000 plant/hm2 and 360 kg N/hm2 level,and the total yield increased by 103.9%.This study suggests that exogenous GA3 can be a useful pathway to promote Sesbania cnnabina production under slight and middle saline conditions,and the optimal gibberellin level in the present study was 140 mg/L GA3.The best performances of comprehensive traits of individual plant were observed at the combine of 120000 plant/hm2 and 180 kg N/hm2 level whereas the maximum total seed yield and characteristics of Sesbania Cannabina populations were reached at the combine of 200000 plant/hm2 and 360 kg N/hm2 level.