Physiological Mechanisms Of Different Controlled Release Compound Fertilizers Influencing On Yield And Quality Of Summer Maize

Reducing the application of nitrogen fertilizer and raising the utilization efficiency were one of the key factors which influenced free-pollution production of maize. Using of controlled release fertilizers was a good choice. In order to elucidate the mechanism of'grain yield increasing, the field experiment was taken for two years and analysed the effect of different controlled release compound fertilizers (CRF and SCF) with different dose on yield and quality of summer maize;and discussed the influences of controlled release fertilizer on photosynthetic traits, mineral nutrition, ammonia volatilization and nitrogen use efficiency of summer maize. The principal results were as follows:1 Effects of controlled release fertilizer on yield of summer maizeThe maize yields of CRFIII and SCFIII treatments increased significantly by 13.15% and 14.15% under the same amount of N, P2O5 and K2O as CCF (common compound fertilizer), CRFII and SCFII (25% less than CCF) treatments also increased significantly by 9.69% and 10.04%, even CRFI and SCFI (only half amount of CCF) can reach the same yields compared to CCF. The increase of 1000-kernel weight was significant while kernel numbers per ear and kernels per row were not increased remarkably. The dry matter accumulation of controlled release fertilizer treatments was also respectively increased, especially in the days after anthesis.The main reason for increasing yield comparing with that of CCF was that the nutrition of controlled release fertilizer was released as the need of maize, which could supply to the nutritious demand of maize in its growth stages. The plant of maize grew strongly, increasing of the plant height and stalk diameter was significant. There were still many green leaves which became effete and fell off latterly. in last stages. The time of higher photosynthesis was longer than that of CCF so that the high-yield was true.2 Effects of controlled release fertilizer on quality of summer maize kernelFertilization improved the quality of maize kernel in varying degrees. The maize content and yield of crude protein (CP), the concentrations of ether extract (EE) and soluble sugar (SS) of CRFIII and SCFIII treatments increased significantly under the same amount of N, P2O5 and K2O as CCF (common compound fertilizer), CRFII and SCFII (25% less than CCF) treatments also increased significantly, even CRFI and SCFI (only half amount of CCF) could reach the same level of nutrition elements compared to CCF. The concentration of starch was different, that of less quantity fertilizer treatments was higher than that of more, but not significantly. The yield of starch was opposite exactly. The ratio of amylopectin and amylose content were enhanced remarkably compared to CK, controlled release fertilizer treatments had no difference from CCF.3 Mechanisms of physiology and biochemistry for controlled release fertilizer affecting yield and quality in summer maizeThe leaf area, photosynthetic pigment (Chl.a, Chl.b and Carno.) content and photosynthetic rate of maize leaf of CCF treatment were higher than those of CRFs and SCFs treatments during early growth stage (before jointing stage), but the differences between fertilizer treatments were not obvious. The trend was opposite during medium and late growth stage and the differences were obvious. CRFIII, CRFII and SCFIII, SCFII treatments could keep higher leaf area, photosynthetic pigment content and photosynthetic rate, dropping slowly relatively. Staying higher photosynthetic capacity during late growth stage was the direct results those conduced. This was important reason that CRFs and SCFs treatments obtained high yield.The N accumulation of plant reflected the condition of N uptake in maize plant during the whole growth stage. The N uptake in plant of CCF was increasing quickly and higher than those of CRFs and SCFs treatments during early growth stage (before jointing stage), while the controlled release fertilizer treatments kept increasing steadily,. The increasing trend was still staying even though during late growth stage, the N uptake in plant was higher than CCF significantly. Most low parts of leaves were still green and its growth stage was longer. The changes showed that controlled release fertilizer could control the release of nutrients and satisfied the nutrients needs of plant during late growth stage and improve the accumulation of photosynthate in plant, that create conditions for high-yield of maize.N concentrations in leaf, stem and grain declined with the growth process, that of controlled release fertilizer treatments declined slower than those of CCF treatment. N uptake in nutritive organs (leaf and stem) increased at first and decreased later, peak value appeared in anthesis or 10 days after anthesis. N uptake in grain increased all through with grain weight increase and the difference was enlarged with the growth process.Controlled release fertilizer applications could improve soluble protein (SP) content in ear leaf significantly and delay the reduction of assimilative key enzyme—NRase activity, that was propitious to N assimilation and synthesis of protein, which were the physiological basic for higher crude protein yield. Soluble protein (SP) content and NRase activity in ear leaf of CRFII and SCFII (25% less than CCF) treatments were also higher than those of CCF treatment significantly. The results showed that controlled release fertilizer had high efficiency of improving N metabolism.Controlled release fertilizer increased the activities of SOD and POD, Elevating amplitude of CRFII,CRFIII and SCFII,SCFIII treatments was great, that of CRFI and SCFI treatments was little. The trend of CAT activity was declining while controlled release fertilizer increased its activity, and at the same time decreased the MDA content. Therefore the protective enzymes to eliminate active oxygen and other peroxide free radicals were improved, as a result leaf senescence process was delayed.4 Effects of controlled release fertilizer on ammonia volatilization from soil in summer maize fieldA kind of venting method was designed to determine ammonia volatilization from soil in summer maize field. The results showed that the ammonia volatilization rate of the controlled-release fertilizer (CRF and SCF) treatments increased slower than CCF treatment and the highest rates appeared at 7 days after the CCF's second day. Total ammonia volatilization from CRF and SCF ranged from 0.78kgN/ha to 4.43kgN/ha and was 51.34% to 91.34% respectively lower than CCF.5 Effects of N efficiency after controlled release fertilizer applications on summer maizeANUE (agronomic N use efficiency) of controlled-release fertilizer (CRF and SCF) treatments were significantly elevated comparing to CCF. SNDR (soil N dependent rate) was the ratio of amount of N uptake in CK treatment and N uptake in N application treatments. The nutrition absorption of maize became less as SNDR was less. This experiment showed that N uptake of the plant was more as the maize yield was higher, and SNDR was less. N uptake of maize from fertilizer was higher. ANR (apparent N recovery) of CRF and SCF treatments'range was from 32.76% to 53.33%, average was 40.78% and higher than 35%(the general average ANR). ANR of CRF treatments was from 32.76% to 53.33% and that of SCF treatments was from 34.88% to 45.99%. ANR (apparent N recovery) of CRF and SCF treatments was higher than CCF treatment and the trend of ANR was declined by increasing fertilizer application.