Study On Growth Characteristics And Corresponding Cultivation Techniques For Hydroponically Grown Long-mat Seedlings Of Rice

Wuyunjing23,a conventional japonica rice cultivar widely-grown in area of the middle and lower reaches of Yangtze River of China,was used as test material.Different rice seedlings cultivated from conventional nutritional soil(CK),matrix(OS)and hydroponics with long mat(HLMS)were used for comparing qualities of seedling and mechanical transplanting,growth characteristics of field population,yield and economic benefit.We also optimize the key factors(planting space,planting depth,different nitrogen fertilizer managements)that affect rice field growth characteristics and grain yield.These results will provide a theoretical foundation and practical reference for the large-scale application of HLMS.The main results of this study are the following:1.Effects of different seedling raising mediums on seedling quality and growth of transplanted riceOur results showed the number of appeared leaves of HLMS was more than those of CK and OS,but the root growth of HLMS was weaker than those of CK and OS,also tillering slower.There was no significant difference in yield among different seedling raising methods(HLMS,CK,OS).However,the seedling quality of HLMS was same as that of CK and OS.No significant difference was observed in mechanical transplanting quality,but the yield of HLMS2 was significantly higher than that of CK and equivalent with that of OS,enabling high-yield and high-efficiency rice production.In addition,the method of raising seedlings with soilless water reduced the production input,and the final ratio of yield and input was significantly higher than that of nutrient soil and substrate.Soilless culture of seedlings is a feasible method for raising rice with high yield and high efficiency.2.Study on suitable transplanting space of long mat seedlings cultivated with Hydroponics for Japonica riceThe missing hill rate decreased accompany with the increasing of mechanical transplanting spaces.The rates of floating seedling had no significant difference among different treatments.Tillers of stem per plant increased significantly while tillers of stem for the whole population decreased obviously.During the stage of panicle differentiation,accumulation of dry matter per plant increased while that for the whole population decreased accompany with the increasing of mechanical transplanting space.There was no significant difference among different seedling raising methods during the heading stage,but increased at the beginning and then decreased during mature stage.High yields were obtained when the spaces at 12 and 14 cm due to the high spikelet number.Thus,mechanical transplanting space between 12 and 14 cm(23.8-27.8 hills/m2)is the suitable space for HLMS to obtain high yield for Japonica rice in area of the middle and lower reaches of Yangtze River.3.Study on suitable transplanting depth of long mat seedlings cultivated with Hydroponics for Japonica riceRice soilless hydroponic technology developed in the field of mechanical transplanting seedlings,but the depth of mechanical transplanting influences the quality of mechanical transplanting,recovery and tillering of the seedling,accumulation of dry matters,yield and yield components.The results showed that the recovery of the seedling was delayed,the accumulation of dry matters reduced and the leaf area index decreased when the depth of mechanical transplanting at 3 cm,and this finally reduced the yield.However,when the depth of mechanical transplanting less than 2 cm,the rates of floating seedling increased,and the grain number per spike and the rate of seed formation decreased,which led to the reduction of yield.Thus,the suitable depth of mechanical transplanting is between 2 and 3 cm.4.Effects of different nitrogen fertilizer management on growth characteristics of Long Mat Seedlings Cultivated with Hydroponics for Japonica riceWith the increase of the amount of nitrogen fertilizer,the rice yield increased while maintained at a certain level when the number of nitrogen fertilizer up to 225 kg·hm-2,and the availability of nitrogen fertilizer reduced significantly.Increasing of the ratio of nitrogen fertilizer during later stages of the plants improved the accumulation of dry matters and yield.Our study demonstrated that the most appropriate amount of nitrogen fertilizer for Japonica rice Wuyunjing23 was 225 kg·hm-2,and the ratio of basic tiller fertilizer and panicle fertilizer was 5:5,which was considered to be the most effective way for utilization of nitrogen fertilizer.