Effect Of Covering With Fly Net On Growth Of Summer Brassica Campestris SSP.Chinensis Makino

Brassica campestris ssp.chinensis Makino in seeding stage is usually called Chinese Little Greens and the foliar age is usually less than10leaves. It is an important green leaves vegetable and very popular among the people. Brassica campestris ssp.chinensis Makino likes cool, stands cold and but doesn’t stand high temperature. In addition, high temperature and high humidity in summer and autumn is one of the main factors which limites the growth. Protection facilities which has more than40℃high temperature at noon in most parts of China, often seriously affect the yield and quality of Brassica campestris ssp.chinensis Makino. Summer with high temperature and high humidity is also the high season for the disease and pest which is very serious during the growth period and we need chemical control. Due to the short growth cycle and the long pesticide-degrading cycle, it is vulnerable to bring about excessive pesticide residues and affect the public health. Therefore, safety of Brassica campestris ssp.chinensis Makino in summer and autumn often becomes a hot social issue of concern to the people. Insect net covering, as a new type of vegetable cultivation technique, was developed in recent years. It has advantage of shading and pest control function, which has played a positive role in pest control in summer and off-season cultivation. Research on effect of covering with fly net on the yield, quality and photosynthesis of Brassica campestris ssp.chinensis Makino is very few.The study uses Shanghai chinese little greens of green leaves vegetable(Brassica chinensis L.) which were eaten widely and have strong heat resistance as test material, uses20accounts,40accounts and60accounts specifications anti-insect network cover cultivation, comparatively researches the anti-insect effect and yield through different accounts number anti-insect network cover cultivation, analysis the effect of mesh insect net covering cultivation on the soluble protein, soluble sugar and VC content of heat-resistant shanghai chinese little greens,and studies the photosynthetic characteristics of shanghai Chinese little greens under different mesh insect nets. Major findings are as follows:Firstly, the study uses shanghai chinese little greens as test material and uses20accounts,40accounts and60accounts specifications anti-insect network cover cultivation to study pest control effect and yield. Results showed that covering insect net cultivation of feather dishes can against heavy rain, prevent insects and disease, and increase the production by comparing with the open field cultivation. Pest control effect is related to accounts, and60mesh insect net is the best and it can kill90%diamond back moth, Pieris rapae sp., Phyllotreta striolata, Cabbage Aphid and Bemisia tabaci. Plant yield comparison tests show that40mesh insect net has the maximum production of1033.8kg-667m-2.Secondly, by analyzing the internal and external environmental factors such as light intensity, temperature and relative air humidity of20accounts,40accounts and60accounts insect net, the results indicate that the insect nets reduced the light intensity in the network, increased temperature and relative humidity of the air, so the influence on network environment has its pros and cons. By analyzing the effect of different insect net specifications on the quality of shanghai chinese little greens, we found that insect nets can improve VC soluble protein and soluble sugars of shanghai chinese little greens, reduce the contents of mineral nutrient elements, such as Ca, Fe, Zn, Mn, Cu and increase the contents of Mg, but not by much.40accounts insect net is more suitable for the cultivation of shanghai chinese little greens in the summer, because the VC contents, soluble protein and soluble sugars is increased by12.83%,48.57%,9.8%respectively. The results of this study has laid a good foundation for further research on covering insect net cultivation of chinese little greens.Thirdly, we used20accounts,40accounts and60accounts specifications anti-insect network cover to cultivate Shanghai Chinese little greens in summer to study the main photosynthetic pigment and photosynthetic parameters. Results indicate that the insect nets have inhibitory effects of light intensity, the greater the number of the insect account is, the more serious the shading is. In addition, a variety of cover conditions can improve the content of photosynthetic pigments. Under the different treatment, the total photosynthetic pigments and carotenoids of40mesh are2.165mg-1-1and0.127mg-1-1respectively. In the three kinds of insect nets,40accounts specifications anti-insect network has the highest net photosynthetic rate of17.837mol·m-2·s-1in the measurement of photosynthetic parameters.