Studies On Techniques Of Establishment And Seed Production In Cleistogenes Songorica

The native grasses play an important role in grass cultivation and ecological restoration.Pot and field experiments were conducted under various conditions to study:1) effects of soil water content on Cleistogenes songorica seed germination,seedling emergence and seedling growth;2)effects of mulching on C.songorica seedling establishment;3)effects of different plant density on seed yield and yield components.The results showed that:1.Soil water content significantly influenced C.songorica seed germination,seedling emergence and seedling growth.The optimal soil water content for seed germination and seedling emergence in sand were 6%-8%;and the highest seedling biomass was attained when soil water content was 8%in the pot experiment.2.Effects of mulches on C.songorica seedling establishment varied with soil moisture conditions.The mulches showed no effects on seedling establishment when irrigated every 5 days but significantly increased seedling survival rate when irrigated every 15 days.Under 15 days interval irrigation condition,seedling establishment rate under sand mulching(40.7%)is the best than other mulching treatment and control (22.2%).Film mulching(23.6%)did not increase seedling establishment in compared to control but significantly greater than mulching with straw(15.9%).The plant height,leaf number,tiller number,leaf area and aboveground biomass with sand mulching were significantly greater than other treatment and control under two irrigated conditions.3.Plant density significantly influenced the C.songorica seed yield.The seed yield of 300,000 plants/hm~2 treatment was significantly greater than other treatments.As the density increased from 50,000 plants/hm~2 to 300,000 plants/ hm~2,seed yield increased form 129 kg/hm~2 to 1344 kg/hm~2,but not significantly different between 300,000 plants/ hm~2 and 500,000 plants/hm~2.4.Plant density significantly influenced the C.songorica aboveground biomass, canopy width,diameter of fertile tillers and leaf area,but not plant height.As the density increased,the leaf area increased;but the aboveground biomass,canopy width and diameter of fertile tillers increased first and then decreased.Plant density significantly influenced the seed yield components,such as fertile tillers/m~2,inflorescences/ fertile tillers,seeds/inflorescence and 1000-grain weight.As plant density increased,the fertile tillers/m~2 increased,but no regularity was observed in the inflorescences/fertile tillers, seeds/inflorescence and 1000-grain weight.5.The path analysis showed that the fertile tillers/m~2 was the most important factor influencing the seed yield.The seed yield were significantly positive correlated to fertile tillers/m~2 for each density treatments,the total correlation coefficients ranged from 0.631(500,000 plants/ hm~2)to 0.812(150,000 plants/ hm~2),the direct correlation coefficient ranged from 0.515(250,000 plants/hm~2)to 0.788(500,000 plants/hm~2),and the indirect correlation coefficients ranged from -0.159(500,000 plants/hm~2)to 0.208(50,000 plants/hm~2).When the plant density were 50,000,250,000 and 300,000 plants/hm~2,seed yield were significantly positive correlated to seeds/inflorescence;and the seed yield were significantly positive correlated to inflorescences/fertile tillers when plant density was 150,000 plants/hm~2;but no correlation was observed between seed yield and 1000-grain weight under all density treatments.In brief,the optimal soil water content for C.songorica seed germination,seedling emergence and seedling growth in sand were 6%-8%.Sand mulching significantly increased the seedling establishment rate and seedling growth under drought condition. The optimal plant density for seed production was 300,000 plants/hm~2,and the fertile tillers/m~2 was the most important factor in determining seed yield.