Effect Of Straw Mat And Other Mulching Materials On Nitrate Metabolizing Of Soil,Roots And The Photosynthesis And Transpiration Of Apple Leaves

Surface coverage is an effective dry farming techniques, and straw mat is made of rice straw.The effective utilization of straw play an important role in social, environmental and ecological. The experiment explored the effect of straw mat and other mulching materials on nitrate metabolizing, soil water temperature environment and available nutrients and apple roots in soil of apple root-zone using three-year old potted apple trees(Malus domestica cv. Starkrimson) treated with mulching straw mat, agricultural carpet, transparent-plastic film and horticultural fabric in spring. The main results are as follows:1. For comprehensive effect of stabilizing soil temperature and increasing the content of water and available nutrients in root-zone soil, the order of comprehensive effect was straw mat, agricultural carpet, horticultural fabric and transparent-plastic film from high to low.The increment of relative water content in the soil mulched with straw mat and horticultural fabric was largest; transparent-plastic film had the highest stabilizing capacity on soil moisture change than other in the four treatments. In summer and early autumn, the temperature increment in the soil mulched with transparent-plastic film was the largest and that was the lowest mulched with straw mat. In late autumn, the temperature increment in the soil mulched with straw mat and agricultural carpet were largest and the maintaining effects of horticultural fabric on soil temperature was the poorest. Straw mat and agricultural carpet made the soil temperature more stabilized. Four treatments all enhanced the stability of soil p H and increased the content of soil organic matter, alkali-hydrolyzable N, available P and available K. The effect of straw mat on increasing soil available K was most obvious.2. Straw mat had the most significant stabilizing effect on the soil nitrate metabolism and transformation. Straw mat increased soil denitrification intensity and nitric nitrogen contents in summer and autumn, and decreased the activity of NR and Ni R in summer. The coefficient of variation of soil nitrification-denitrification intensity and NR activity after mulching straw mat was the lowest among the four mulching treatments. Agricultural carpet increased the soil NR and Ni R activity in summer, the nitric nitrogen contents between summer and autumn and the denitrification intensity in autumn, and decreased soil denitrification intensity in summer. Transparent-plastic film increased the nitrite nitrogen contents in summer, the contents of nitric nitrogen between summer and autumn, the nitrification intensity and Ni R activity in autumn, and decreased soil nitric nitrogen contents in summer. Horticultural fabric increased soil denitrification intensity in summer, nitrification intensity in summer-autumn and autumn and the contents of nitric nitrogen in autumn.3. The root activities of agricultural carpet and transparent-plastic film were higher than straw mat and horticultural fabric, and the stability of transparent-plastic film was best. The root NR of agricultural carpet and straw mat and the root NOS of straw mat were most obvious. The production of NO in roots was increased significantly after mulching straw mat. Agricultural carpet made the root NR and NOS more stabilized. The root fractal dimension was the highest and root structure was more complex after mulching straw mat, the root diameter, root volume and surface-area were the largest and the roots were thick and strong after mulching agricultural carpet; the total root length the highest after mulching transparent-plastic film; the number of root tips was the most after mulching horticultural fabric.4. Four treatments all increased chlorophyll and photosynthetic rate, especially in mulching horticultural fabric. Agricultural carpet made the chlorophyll and photosynthetic rate more stabilized. The effect of mulching on transpiration rate was bigger, so, the change of water use efficiency was affected greatly too. Straw mat made the new shoot thick and long; Horticultural fabric made the new shoot thick and short; Transparent-plastic film made the new shoot slender and long. The plant trunks of straw mat and horticultural fabric were highest.