Effect Of Planting Date, Mulching And Soil Moisture On Growth And Development Of Onion

Temperature and moisture is the two most important indexes to plant growth. The suitable temperature and moisture are of great significance to crop assimilation, growth, , productivity and quality. Soil temperature and moisture are affected by many factors including: climatic conditions, mulching, and irrigationTo estabolish an appropriate onion planting mode, for improved yield and quality, a field experiment was conducted under the climate condition of Hexi region,The experiment consisted 12 treatments of four explanting dates, three mulching styles, and three irrigation quantities. The main fingdings are as following:1.Effect on growth and development of onion of different planting date. the onion which planted on April 3 th, it formed bigger assimilation system on the early growth ,so the growth,yield and quality of onion are best in eventually. the temperature and meteorological conditions of minqin is proper to the growth of Onions. the colonization of April 18 th is following and it is too late for planting on May 18th.although the death of onion were strained, later high temperature against plant growth and photosynthesis and the temperature exceeds the suitable scope grow onion it also Restrain the growth of the leaf and cause assimilation system built slowly.such as the plant height(76.87cm) and stem diameter(2.21cm) was highest of onion which were planted on April 3th ,it is lowest for plant height(57.66cm) and stem diameter(1.48cm) of onion which were planted on May 18th . the plant height and stem diameter of onion were 24.99% and 33.03%which were planted on April 3th higher than that of onion which were planted on May 18th respectively. The yield of April 3th planting and April 18th treatment were 7070.2 kg/667m2 and 6714.5kg/667m2 respectively.the yield increase rate of two planting date treatments were 10.04% and 4.49% respectively. May 18th treatment decrease rate was 39.4%; Yield water efficiency and unilaterally water efficiency of April 3th planting and April 18th treatment are higher than contrast. Yield water efficiency and unilaterally water efficiency of April 3th planting treatment was 13.25kg/m~3 and 7.95yuan/m~3,which were 1.17kg/m~3and 0.7yuan/m~3 higher than contrast.2.Effect on growth and development of onion of different mulching. the soil temperature of 5cm,10cm and 20cm under black plastic,transparent plastic and sand in the whole growth period of onion were 25.25℃,26.56℃和25.18℃;24.35℃,24.64℃和23.71℃;22.79℃,23.34℃和22.19℃。Soil temperature of transparent plastic 1.31℃and 1.38℃of 0~5cm is higher than black plastic and sand respectively;black plastic 0.07℃higher than sand;Soil temperature of transparent plastic 0.29℃a nd 0.93℃of 0~10cm is higher than black plastic and sand respectively;black plastic 0.64℃higher than sand;Soil temperature of transparent plastic 0.55℃and 1.15℃of 0~20cm is higher than black plastic and sand respectively;black plastic 0.6℃higher than sand. the tread of soil temperature of 5cm,10cm and 20cm increased first and then decreased under different mulchings. the maximum is 32℃,34℃and 33.17℃;30.5℃,32℃and 30.67℃;30.5℃,32℃and27.67℃respectively. But root of covered transparent film is premature consenescence and it caused plant consenescence in the last stage of growth. and affect the yield of onion the effect of Transparent plastic film is less,sand film is the worst. Sand film treatment decrease rate was 32.5% than black plastic film; transparent plastic film decrease rate was2.8%,there was no difference between transparent plastic and black plastic obviously. But the two was higher than sand film. unilaterally water efficiency ang yield water efficiency of black plastic were 0.25 yuan/m~3 and 0.41kg/m~3 higher than transparent plastic. unilaterally water efficiency ang yield water efficiency of black plastic were 3.02kg/m~3 and 1.82 yuan/m~3 higher than transparent plastic.3.Effect on growth and development of onion of different soil moisture. onion survival rate(71.7%) is highest in the treatment of full irrigation (533.6 m~3/667m2), mild water (433.6 m~3/667m2)is less(68.3%),moderate water(380.2m~3/667m2) is the worst(64.8%).onion survival rate of full irrigation was higher than moderate water obviously. Effect on growth and development of onion of different mulching: onion survival rate(71.7%) is highest in the treatment of black plastic (70.76%), transparent plastic (69.69%) is less, sand film is the worst(64.30%). During mature stage, FW of bulb of onion of full irrigation were 29.67% and 43.42% higher than mild water and moderate water. FW of above ground part of full irrigation were 21.95% and 40.86% higher than mild water and moderate water . FW of bulb of onion of black plastic were 9.79% and 33.95% higher than transparent plastic and sand film. the yield of moderate water and mild water decrease rate was 48.88% and 29.18%. unilaterally water efficiency ang yield water efficiency of full irrigation were 12.84% and 28.25% , 12.97%and 28.29% higher than moderate water and mild water respectively. Compactness,pyruvic acid, Vc and Onion oil of full irrigation treatment is highest, mild water is less and moderate water is the worst. Soluble sugar and Soluble protein of moderate water were 26.85% and 12.81%,23.10% and 10.33% than full irrigation and mild water respectively. Compactness,pyruvic acid,Vc and Onion oil of black plastic treatment is highest, transparent plastic is less and sand film is the worst. Soluble sugar and Soluble protein of sand film were 17.30% and 13.74%,22.62% and 16.373% than black plastic and transparent plastic respectively.4.Effect on photosynthetic character of onion of different planting date,mulching and soil moisture. The effect of planting date on Pn of each treatment in onion leaves significantly different from 9:00 to 15:00. Pn is highest at 10:00, which were 12.03,11.93,11.46 and 10.33umol/m-2s-1 respectively on April 3th, April 18th, May3th and May 18th. T1 and T2 treatment were 4.97% and 4.10% higher than May3th; Gs were 583.62,523.21,473.43 and 389.33mmol ? m-2 ? s-1 at 8:00 on April 3th, April 18th. Pn and Gs of onion leaves were highest under black plastic mulching. Pn of black plastic and transparent film mulchings were 10.56% and 8.81% higher than sand mulching. Gs of black plastic and transparent film mulchings were 12.02% and 8.60% higher than sand mulching. Pn and Gs on different soil moisture treatment show: black film> Transparent film> covered of sand .there were no significant differences between black film and Transparent film,the two was significantly higher than covered of sand.