Study on the Feeding Intensity of Grass Carp at Different Physiological Stages on Water Hyacinth ( Eichhornia crassipe )

[Objectives]This study was conducted to investigate the feeding intensity of different sizes of grass carp on water hyacinth.[Methods]Grass carp of 10 sizes,i.e.,50,100,150,200,250,300,350,400,450 and 500 g,were put in cages.Thirty grass carp were stocked in each cage,and only water hyacinth was fed.The grass carp were caught after 120 d,and the food intake and growth of the grass carp were analyzed.[Results]The body weight of all sizes of grass carp increased significantly,and the overall length of grass carp increased significantly.Compared with feeding feed,the body length and body weight in the experimental treatments were lower,and they were more slender;and the feed coefficient of small-sized grass carp was slightly larger than that of large-sized grass carp.When the stocking size was above 414.7 g,the net weight gain of grass carp increased rapidly,and the total food intake also increased.[Conclusions]This study provides a theoretical basis for achieving an ideal purification effect of water hyacinth on aquaculture water by maintaining the growth of grass carp and the biomass and coverage of water hyacinth within suitable ranges.

Dry Matter Accumulation,Moisture Content in Maize Kernel and Their Influences on Mechanical Harvesting

[Objective] The aim of this study was to investigate the dry matter accumulation,moisture content in maize kernel and their influences on mechanical harvesting.[Methods] Using Zhengdan 958,Xianyu 335,Hongda 8 and Liyu 16 as experimental materials,we preliminarily measured the dynamic changes of dry matter accumulation and moisture content with the days after pollination lasted,and investigated the effect of moisture content in kernels on mechanical harvesting of Zhengdan 958 and Liyu 16.[Results] During summer growing season,Zhengdan 958 and Liyu 16 became physiologically mature and suitable for harvesting at about 51 days after pollination,Xianyu 335 and Hongda 8 required 58 days to become physiologically mature and suitable for harvesting after pollination.At physiologically mature stage,the moisture contents in kernels of Zhengdan 958,Xianyu 335,Hongda 8 and Liyu 16 were respectively 33.74%,28.86%,32.05% and 35.24%,respectively.Adopting mechanical harvesting at physiologically mature stage,the kernel loss rate of Zhengdan 958 and Liyu 16 was consistent with the range of mechanical operation index（kernel loss rate of 0.84%≤2%）,while the percentage of broken kernels did not accord with the range of mechanical operation index（kernel crashing rate of 10.12%≧1%）.The results indicate that Zhengdan 958 and Liyu 16 are not suitable for mechanical harvesting using full feeding combine havester.[Conclusion] This study provided theoretical basis for improving the maize harvest index under delayed harvesting.