Overlapped Tray Seedling Raising Model for Mechanical Transplanting of Rice

With the development of China's social economy,transfer of rural labors,and rise of labor costs,the rice production technologies are changing from manual operation to mechanical operation.The core of mechanical rice production is mechanical planting,while the key to mechanical planting is the seedling raising.On the basis of analyzing and studying the problems and experience of traditional mechanical transplanting of rice,a new overlapped tray seedling raising model was introduced.Main features of this model: substrate seedling raising and overlapped seedling tray.The seedling trays for seeding line are overlapped,and the overlapped trays are moved into the seedling room with controlled temperature and humidity.The temperature of the seedling room is controlled at 30-32℃,and the humidity of the seedling room is controlled at above 90%.After about 48 h,when the seedling height reaches 0.5 cm,move the seedling trays to the nursery.This model consists of one seeding center( seedling raising center) and N nurseries,to realize 1 + N seedling raising for mechanical transplanting of rice.One seeding center can provide seedlings for several hundred to several thousand hectares of mechanical transplanting of rice,and provide a new model for social services.This model could improve the quality of seedlings,increase the seedling survival rate by about 20%,reduce the seedling raising costs by 15%-20%,reduce the seedling raising risks,and greatly increase the utilization rate of the site and equipment of seedling raising center.

Effects of Low Temperature after Flowering on Grain Filling and Plant Hormone Contents in Rice

Four varieties, indica-japonica hybrid rice Yongyou 538 and Yongyou 17, indica rice Zhongzheyou 1 and japonica rice Zhejing 88 were treated under low temperatures in different time periods of grain filling stage, to analyze endogenous hormone changes and differences in different treatments in grain filling process. The results showed that the effects of low temperatures in different time periods after flowering on grain filling showed an order of early stage 〉 middle stage 〉 late stage, while the difference between the effects of lower temperatures on grain filling in middle and late filling stage was not significant, and the effects of low temper- atures on Yangyou 17 and Zhongzheyou 1 were higher than those on Yangyou 538 and Zhejing 88. Low temperature in early filling stage after flowering aignifieanfly slowed grain filling of Yongyou 17 and prolonged filling duration, while the effect on Yongyou 538 was not significant. Under low temperature treatments after flow- ering, changes in endogenous hormone contents in various varieties differed to certain degrees, IAA and ZR contents in grains of Yongyou 17 in early and middle filling stage decreased significantly, while GA3 and ABA contents were improved remarkably ; and Yongyou 538 showed significantly reduced GA3 content in grains, but higher IAA and ZR contents, which were the main reason for normal filling in grains. Proper hormone regulation measures could be taken in production to improve filling of rice grains under low temperature.

Structural feature and tectonic evolution of Awati-Bachu area in Tarim Basin

The research area is situated in the western part of Tarim basin,which includes Awati depression and Bachu uplifted block. It underwent three times processes of compression in a large scale and a near term extension since Cambrian. The first compression occurred during Middle Cambrian to Devonian, which formed fault band folds in NW axial direction. They were "under-water uplift"and distributed all over the research area. The second compression occurred in Late Permian and formed fault band folds and a few fault propagation folds in NS axial direction. They are developed near Tumuxiuke fault belt and the northern research area. The western anticline is bigger than the eastern one in extent and size. The third compression occurred during Palaeogene to Quaternary and formed tumuxiuke fault belt and fault propagation folds in NW direction. They are distributed over the south part of the research area. Tumuxiuke fault belt is a big scale dextral reversed strike-slip fault belt; it transformed or destroyed the fold structure of the research area. A short-term extension occurred during Early Permian. Tarim Basin is in the rift forming stage of craton, and there exist widespread basic volcanic rocks, basic intrusive bodies and dikes.

Root morphology in response to nitrogen supply in mid-season indica rice cultivars released in different decades

Dear Editor,Roots,as a major organ of plants,are involved in nutrient and water acquisition,and might play a vital role in yield increase and efficient N absorption with genetic improvement.Because of the great differences in growth period and pattern between the old and new rice cultivars,it is difficult to clarify how genetic improvements contribute to root growth in rice.For example,for a solution culture system,Wu et al.suggested that total root length increased with increasing year of release for maize hybrids,while shoot dry weight,

Visible-light-induced chemoselective reactions of quinoxalin-2(1H)-ones with alkylboronic acids under air/N_(2) atmosphere

A visible-light-induced chemoselective reactions of quinoxalin-2(1 H)-ones with alkylboronic acids in the presence of air(O_(2)) and N_(2)atmosphere was developed under transition-metal free conditions, providing 3-alkylquinoxalin-2(1H)-ones and 3,4-dihydroquinoxalin-2(1H)-ones, respectively. The overall strategy accommodates a broad scope of substituted quinoxalin-2(1H)-ones and alkylboronic acids with good to excellent product yields.