Regulating Effects Of Applying Biogas Liquid Manure On Source-sink Metabolism And Formation Of Grain Yield Of Summer Maize

Biogas liquid is a kind of high quality organic maneure, which is made of ferment product from dejection and crop stalks. There have been some studies about effect of biogas liquid on yield of maize, but studies about the mechanism of increasing yield by application of biogas liquid are limited. In this paper, regulating effects of biogas liquid on growth, sourse-sink metabolism and grain yield of summer maize were studied. The aim is to provide references for reasonable use of biogas liquid manure and realizing high yield and efficiency in summer maize production.A field experiment using hybrid Zhengdan 958 as material was conducted. Three biogas liquid manure application rates (15000,22500,30000 kg?hm-2) included in the experiment: 5000 kg·hm-2 biogas liquid manure applied at jointing, big trumpet and tasseling stages respectively(T2),7500 kg·hm-2 biogas liquid manure applied at jointing, big trumpet and tasseling stages respectively(T3)and10000 kg·hm-2 biogas liquid manure applied at jointing, big trumpet and tasseling stages respectively(T4). The main rusults are as follows.1. Effect of applyling biogas liquid manure on canopy characters of summer maize.Plant dry matter accumulation is important to formation of economic yield of summer maize.Application of biogas liquid increased leaf area index, shoot dry weight, plant height, ear position height, stem diameter and plant height uniformity to a certain extent. Of the three application rates used in this experiment, 22500 kg·hm-2 (7500 kg·hm-2 applied at jointing, big trumpet and tasseling stages, respectivtly) had the best effect on the characters abovementioned.2. Effect of applyling biogas liquid manure on chlorophyll content and photosynthetic rate in leaves of summer maizeChlorophyll content and photosynthesis rate in leaves were in sequence of T3> T4> T2> T1>CK, which showed that T3 was best to maintaining high chlorophyll content and photosynthesis rate. 3. Effect of applyling biogas liquid manure on activities of nitrate reductase (NR), glutamine synthetase (GS) and sucrose phosphate synthetase (SPS) in leavesApplication of biogas liquid manure could enhenced activities of nitrate reductase (NR) glutamine synthetase (GS) and sucrose phosphate snthetase (SPS) in leaves of summer maize. Of the three application rates in this experiment, the application rate in T3 (7500 kg·hm-2 applied at jointing, big trumpet and tasseling stages, respectivtly) had the best effect on increasing above enzymes of summer maize. Thus, the trentment T3 was more beneficial to accumulate assimilation in source4. Effect of applying biogas liquid manure on activity of sucrose synthetase (SS) in grains of summer maizeApplication of biogas liquid manure increased activity of sucrose synthetase (SS) in grains of summer maize. The application rate of T3 (7500 kg·hm-2 applied at jointing, big trumpet and tasseling stages, respectivtly) had the best effect on increasing sucrose synthetase (SS) of summer maize. Thus, the trentment T3 was more beneficial to keep the high conversion of assimilation capability in sink.5. Effect of applyling biogas liquid manure on activities of antioxidant enzymes (SOD,CAT),MDA content and resistanceT3 and T4 not only had higher SOD and CAT activitives, but also had lower MDA content, which indicated that the trentment (T3) and (T4) improved the ability of mesophyll cell to scavenge active oxygen reduced level of membrane lipid peroxidation and further kept the cell membrane stability.6. Effect of applyling biogas liquid manure on grain yield of summer maizeThe yield parameters such as ear diameter, ear length, grain rows per ear, grain, per row, kernels per ear, 1000-kernel weight and yield per unit area were improved significantly by the application of biogas liquid manure compared to control. The yield of each treatment was in sequence of T3 > T4 > T2 > T1 > control. The yield of T1,T2,T3 and T4 increased 23.7%,26.29%,40.7%,36.67% compared to control respectively. Of the three application rates in this experiment, 22500 kg·hm-2 (7500 kg·hm-2 applied at jointing, big trumpet and tasseling stages, respectively) obtained highest yield (14006.7 kg·hm-2), increasing by 40.7% compared to the control.7. Mechanism of increasing yield by applying biogas liquid manureAccording to the results, mechanism of increasing yield by applying biogas liquid manure was summarized. On the basis of selecting high yield potential varieties of summer maize, proper application of biogas liquid manure could regulate growth, source-sink metabolism and antioxidant enzymes activities. For instance, T3 treatment could increase leaf area index (LAI), improve population structure, and increase chlorophyll content and photosynthesis rate, enhence activities of nitrate reductase (NR) glutamine synthetase (GS) and sucrose phosphate snthetase (SPS) in leaves of summer maize, maintained a strong ability of assimilate provision. Moreover, It was beneficial to improve SS activities in grains, enhance the capacity of starch synthesis and increase grains filling rate. Thus, the high conversion of assimilation capability in sink was kept, protective enzymes were improved. Consequently, high yields and efficiency was realized.