Development Of "Seed-mat" And Evalution Of Seedling Quality For Mechanized Rice Transplanting

Rice is one of the most important food crops in the China.It is planted by different methods such as seedling transplanting,seedling throwing and direct seeding etc.,and seedling transplanting is the major planting method under intensive production system.In recent years,due to the large number of rural laborers shift to the secondary and tertiary industries,labor becomes a shortage and labor price increases.It also results in lower comparative benefit,the proportion of transplanting rice by machine instead of traditional artificial planting is increasing.At present,the technical bottleneck in machine transplanting is the lack of large-scale factory seedling technology.The main problems in the existing machine-transplanting seedlings include large soil consumption in the tillage layer,high energy consumption due to heavy carpet weight,poor seedling packing force,long seedling recover period after mechanical transplanting,and high leakage rate,which require to be highly improved.Therefore,this study explored the use of materials such as husk crushed material as a raw material to create a “seed-mat” to acquire a soilless cultivation of carpet-like seedlings suitable for rice mechanized rice transplanting.Through the screening of different types and amounts of bio-starch,a 28 cm × 58 cm seed-matrix-integrated lump “seed-mat” was produced;based on the lump “seed-mat”,the nutrient element formula and the regulator formula of the lump “seed-mat” was selected,and the quality of the seedlings and the mechanical transplanting adaptability under different seeding methods were compared.The purposes of our study were to establish a lump “seed-mat” with soilless seedlings and integrated seeds with rice husk as raw material,the quality of seedlings was evaluated,to provide technical support for the application of the soilless seedling “seed-mat”.The main results showed that:1.The crushed husks was used as one of the materials for the production of the sheet-like “seed-mat” with the size of 28 cm×58 cm.By optimizing the ratio of binder and matrix composition,integrating the cost and structural strength of seed-mat,we selected 60 g/plate of corn oxidized starch as the most suitable binder for seed-mat.On the basis of the optimum formula for a “seed-mat”,the total weight of the “seed-mat” for 1 hm2 was 164.5 kg,which was the 11% of the weight of traditional carpet seedling with nutritional soil,and the cost of raising seedling was 416.5kg/hm2,which was equivalent to that of traditional substrate nursery seedling.2.The nutrition formula of “seed-mat” was established.The best N,P,and K nutrition formulas for “seed-mat” was a combination of 1 g/plate,0.6 g/plate and 0.2 g/plate,respectively using crushed husk as material.Besides,in the case of no fertilizers,the optimum amount of commercial sturdy-seeding agent was added in “seed-mat”.The shoot dry weight,root dry weight,length of the longest root and the ratios of shoot dry weight to height(DW/H)of seedling,roots number and root volume compared with other nutrition formulas were all relatively higher,as well as the high quality of seedling when adopt N,P,and K nutrition formulas.In the case of no fertilizers,the quality of seedling had an improvement firstly,followed by a continuous reduction,with the increase of the amount of commercial sturdy-seeding agent in “seed-mat”.3.Established the method that the bast fiber films were impregnated by paclobutrazol and non-direct contact with seeds on the regulation of seedlings height and tillers differentiation.The result presented that 20 mg/L had the best effect and excessive concentration had significant inhibiting effect on the growth of seedling.4.The comparison between seedlings quality of the “seed-mat” in dry and wet nursery seedlings pointed out that the root of “seed-mat” under wet nursery seedling was more flourishing than dry nursery seedling and the force of root entanglement of wet nursery reached 84 N-97 N,while in the dry nursery was 17 N-34 N.Therefore,when raising seedlings using “seed-mat”,we suggested to adopt wet nursery seedling method.In summary,developed “seed-mat” material formula together with seed and soilless substrate,optimized the seedlings substrate board nutrition formula and the treatment of non-contact control seedling height,the soilless “seed-mat” cultivated high quality seedlings suited for mechanized transplanting were realized,to provide technical support for the application of the soilless seedling “seed-mat”.