Effects Of Sowing Date,Density And Shading On Yield And Quality Of Non-Heading Chinese Cabbage

Non-heading Chinese cabbage is also called green vegetable,'youcai' and Chinese little greens,etc.Non-heading Chinese cabbage seedling is the seedling stage of Non-heading Chinese cabbage(Brassica rape L.ssp.Chinensis),native to China.It adapts to cool and the optimum growth temperature is 18-20?.High temperature and strong light will lead to 'summer off-season',which is known as lack of green leaves vegetables supply.From April to October,temperature exceeds the growth temperature of non-heading Chinese cabbage seedling in rain-shelter and insect-proof cultivation in plastic tunnel.What's more,the temperature and light conditions in summer are unfavorable to the growth of non-heading Chinese cabbage seedling,which is easy to cause growth disorders.According to the characteristics of temperature and light,suitable planting density and shading rate can effectively alleviate the damage caused by high temperature and strong light,which is conducive to the growth,yield and quality improvement of non-heading Chinese cabbage.The experiment was based on the characteristics of temperature and light in different sowing dates,2 cultivation measures(density and shading rate)were adopted to investigate the effects of density on growth of non-heading Chinese cabbage in different sowing date to find suitable density under different sowing dates.According to the environmental characteristics of high temperature and strong light,we select the appropriate shading rate to ensure good yield and quality in different periods.In addition,by means of the yield and quality of different types of Chinese cabbage at different sowing dates,we can make clear the suitable cultivar in different sowing date.The aim was to put forward a set of cultivation techniques to deal with different sowing dates,providing experience for the production of high quality and efficiency.The main results are as follows:1.We used non-heading Chinese cabbage 'Qinglan' and 'Kangre605' as materials,which was cultivated in insect-proof and rain-shether plastic tunnel,and setted up 1125 plant,875 plant,625 plant and 375 plant per square,sowing in April 9th,May 17th and August 18th.The effects of growth density and sowing date on the growth,yield and quality of non-heading Chinese cabbage were studied.The results show that using the density of 1131.33 and 1146.67 plants per square sowing of 'Kangre605' in April 9th and May 17th could achieve high yield and good quality.Using the density of 1226 and 1216.67 plants per square sowing of 'Qinglan' in April 9th and May 17th could have a high yield and good quality.773.33 plants per square sowing of 'Kangre605' and 777.33 plants per square sowing of 'Qinglan' in August 18th would achieve high yield and good quality.However,seedling number is reducing in August 18th,and we need to increase the amount of seedling to ensure a suitable density.What's more,'Kangre605' has higher yield and better quality in April 9th,May 17th and August 18th according to our research.2.In order to study the effects of sowing date and shading rate on the growth,yield and quality,we used non-heading Chinese cabbage seedling 'Kangre605','Qinglan' and'Huangmeigui' as the object of study and cultivated in insect-proof and rain-shether tunnel with shading rate 0%,30%,45%,60%,75%while the actual shading rate is 0%,29.3%,43.2%,54.2%and 62.6%after covering sun-shade net sowing in June 6th,July 16th and August 18th respectively.The results show that in June 6th,'Kangre605' had high yield in no shading treatment and good quality in 30%shading rate.'Qinglan' had high yield in 45%shading rate and good quality in 30%shading rate.'Huangmegiui' had high yield in 45%shading rate and good quality in 30-45%shading rate.In a word,using the variety of'Huangmeigui'had a best effect and covering sun-shade net with 30-45%shading rate could improve the production and quality in June 6th.Sowing in July 17th and August 18th,increasing shading rate had a obvious effect on yield improvement,the shading rate of 60%made a higher yield and 45%shading rate made better quality.In summary,it's more suitable to use 'Huangmeigui'in July 16th,and 'Kangre605' in August18th.