| This paper indicated that the mulched drip irrigation inhibited soil air exchange,which leaded to cotton transient hypoxia in soil.Soil nutrient availability and nutrient absorption of cotton was affected,which impacted the growth of cotton.It studied the mechanism of effect of aeration irrigation on soil environment and the growth of cotton under mulched drip irrigation.The effect of 6 kinds of aeration methods was studied by indoor and experiments.Micro bubble generation device and urea peroxide were chosen.The 5 treatments?CK0,CK,PO,PCO,CO?in the hydroponics experiment and 3 treatments?CK,PO,CO?in the field experiments were carried out in 2014 and 2015 in order to research the effect of aeration on the agronomic and nutritional characteristics of cotton,physiological and growth characteristics as well as the soil environment.The oxygen consumption of cotton in bud stage and the synergistic mechanism of the physical oxygen and chemical oxygen on the growth of cotton were explicated.The effects of aeration on soil nutrient,microorganism and enzyme were studied preliminarily.Aeration could improve the soil oxygen environment and soil fertility,promote the growth of cotton,and provide the theoretical guidance for promoting the potential yield of cotton.The main results showed as follows:?1?The results of simulated experiments showed that the urea peroxide was better in the chemical oxygen and micro bubble generation device was better in the physical oxygen;The dissolved oxygen concentration of irrigation water increased significantly with the increasing of the oxygen concentration of micro/nano-bubble generating device,and it would gradually reduce along with the distance increasing.The rate of decay of DO was also increase with the increasing of the dissolved oxygen concentration in the irrigation water.?2?The results of hydroponics experiments showed that aeration water could significantly improve cotton seed germination rate,germination index and vigor index.Aeration could significantly promote the cotton root volume,total root absorption area,root activity area,root biomass,aboveground biomass,plant height,nitrogen uptake,phosphorus uptake,potassium uptake,SOD?POD and CAT activities in the cotton bud stage.The results showed:PCO>PO>CO>CK,PCO was the best.And it was proved that per plant oxygen consumption was 2.84?g·L-1·h-1-4.84?g·L-1·h-1 in the cotton bud stage.The oxygen consumption of cotton increased with the dissolved oxygen concentration of hydroponics solution increasing.Aeration could significantly decrease MDA content,which indicated that the cotton plant was hypoxic under hydroponics conditions,and aeration could relieve the degree of hypoxic.?3?The results of field experiments showed that aeration could reduce the available nutrient and organic matter contents in 0-40 cm soil layer.The decline of soil nutrient in20-40 cm soil layer is more than 0-20 cm.Aeration could promote the mineralization of soil organic matter,aeration increased soil nutrient availability and promoted the absorption of nutrients of cotton plant.Aeration could increase bacteria,fungi,soil microbial quantity and inhibit the activity of actinomycetes yet improve the activity of urease.?4?The field experiments also showed that aeration irrigation coul significantly increase the cotton plant height,stem diameter,biomass,boll number,boll weight and yield.The results of agronomic characters showed:CO>PO>CK,The results of boll number?boll weight and yield showed:PO>CO>CK,there were different effects on growth and yield of cotton between the physical aeration and chemical aeration.Aeration could promote the absorption of nitrogen,phosphorus and potassium in cotton,the results showed:CO>PO>CK;It was that aeration could help cotton on the nitrogen phosphorus and potassium absorption,aeration was conducive to nutrient accumulation so as to improve the yield of cotton.Aeration could enhance the root activity and SOD?POD activity,thereby enhancing the nutrient absorption and stress resistance of cotton.Aeration could decrease MDA content,which indicated that the cotton was hypoxic with drip irrigation under mulch,and aeration could relieve the degree of hypoxic.Aeration could reduce the efficiency of light conversion of weak light,increase the net photosynthetic rate,promote the accumulation of photosynthetic products and fasten the growth of cotton so as to reduce the content of chlorophyll. |
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