Effects Of Balanced Fertilization On Mulberry Yield And Quality And Its Fertilization Model

The silk industry is the traditional industry of China with5,000years of history. The silk industry in China, which is competitive industry and in a monopolistic position in the international market, has made a significant contribution to national economic development and export. Mulberry is an important material basis of the silk industry, the level of mulberry leaf yield per unit area of and its quality directly affects the growth and development of the silkworm and the production and quality of cocoons and silkworm eggs, thereby affecting the economic benefits of the sericulture industry as a whole. Mulberry is a perennial economic forest tree species with high ecological value. Furthermore, the mulberry with high nutritional value, good palatability, no feeding obstacle, high digestion rate, in addition to feed silkworm, is currently of the most potential for development among the woody forage plants; and it can be developed as a high-quality livestock feedstuff. Mulberry leaves are rich in1-DNJ, flavone and other natural active ingredients, which have significant effect on lowering blood sugar, anti-oxidation and anti-age. Therefore, the mulberry is also of great potential in the fields of both food and medicine. The yield per unit area, quality and the level of active ingredient content of mulberry leaves and branches are not only related to varieties of mulberry, pruning and irrigation, but also closely related to the mulberry nutrient management and the mulberry nutritional characteristics.According to fertilization problems in the main producing areas of hilly sericulture in Sichuan Province, the modern fertilizers quadratic regression "3414" experimental design was used to conduct field trials in this study. The effects of N, P and K on mulberry in the aspects of growth and development, dry matter accumulation, photosynthetic characteristics, protective enzyme activities, membrane lipid peroxidation, utilization and distribution of nutrient uptake, leaf quality and content of active ingredients were studied in this paper. The results revealed the laws of growth and development, nutrient uptake and distribution, quality formation and yield formation. The fertilization parameters of mulberry were also systematically studied to build and efficient and high quality fertilization, which provide a scientific basis for the rational fertilization of the local mulberry. The main results in this study were listed below:1. The effect of N, P and K on the growth and dry matter accumulation of mulberryTo promote mulberry growth and development and improve the unit area of mulberry leaf yield of dry matter accumulation, the modern fertilizers quadratic regression "3414" experiment design was conducted in the summer cutting pruning, perennial test mulberry to study the effects of N, P and K treatments on the growth and development indicators of mulberry in different growth stages of leaves, twigs, shoots and leaf yield per plant, etc. The results shew that with the growth and development process moving forward mulberry main indicators of growth and development was gradually increased, and vigorous early growth and development with a decrease at the late stage; the right amount of NPK fertilizer can promote the growth and development of mulberry, while inadequate or excessive fertilization is not conducive to the mulberry normal growth and development. Spring and autumn per plant leaf yield survey analysis shows that the per plant leaf yield throughout the year in autumn was significantly higher than that in the spring; with the increase of NPK fertilizer application rate, leaf yield per plant gradually increased, and each reached maximum at the levels of two, and additions of fertilizer decreased leaf yield per plant. Effect of nitrogen fertilizer on plant leaf yield performed of N2>N3>N1>N0, phosphorus and potassium on the plant leaf yield performance of the P2>P1>P3>P0and K2>K1>K3>K0respectively.Spring and autumn dry matter accumulation analysis shew that the dry matter accumulation performance of leaves>twigs> shoots, and autumn>spring in the twig leaves, while spring>autumn in the twigs; Effect of nitrogen fertilizer on dry matter accumulation performed of N2>N3>N1>NO in leaves, N3>N2>N1>NO in the spring shoots; N2>N1>N0>N3>,N3>N2>N1>N0in the autumn and spring twigs; phosphorus fertilizer on dry matter accumulation performance of P2>P1>P3>P0in leaves, P2=P3>P1>P0in spring shoots and P2>P3>P1>P0, P3>P2>P1>P0in spring and autumn twigs respectively; potassium fertilizer on dry matter accumulation performance of K2>K1>K3>K0, K3>K1>K0>K2in spring shoots, and K3>K2>K1>K0, K2>K1>K3>K0in spring and autumn twigs respectively.By building an effect equation of fertilization with hectares of mulberry dry matter accumulation as a function and fertilizer nitrogen, phosphorus and potassium fertilizer levels as the factors, mulberry leaf dry matter accumulation, the shoot dry matter accumulation and branches dry matter accumulation and fertilization in the amount of fertilizer effect equation P value<0.05, equation fitted successfully. The results suggested that the recommended fertilization amount was694.36Kg/hm2N,198.15Kg/hm2P2O5,274.26Kg/hm2K2O, the maximum amount was8045.04Kg/hm2based on the leaves dry matter accumulation; the recommended fertilization amount was1000.05Kg/hm2N,242.04Kg/hm2P2O5,218.01Kg/hm2K2O, the maximum amount was5969.05Kg/hm2based on the twigs dry matter accumulation; the recommended fertilization amount was883.76Kg/hm2N,204.48Kg/hm2P2O5,426.59Kg/hm2K2O, the maximum amount was1410.24Kg/hm2based on the spring shoots dry matter accumulation. After proved by production practice, the best fertilization program will provide a reference for the construction of high quality mulberry of hilly silkworm in Sichuan Province.2. Effect of N, P, K on the photosynthetic characteristics of mulberryPhotosynthesis is one of the important physiological processes in mulberry; more than90%of dry matter of mulberry trees is from the photosynthesis in mulberry leaf; and the strength of photosynthesis directly affect the yield and quality of mulberry leaves. Photosynthesis is affected not only by the genetic characteristics of the crop itself, but also by many environmental factors including humidity, temperature, light intensity, concentration of carbon dioxide, minerals, nutrition, etc. At present, many studies have focused on the basic characteristics of mulberry photosynthesis and the response of photosynthetic rate to light intensity, temperature, CO2concentration and micro-meteorological factors, the effect of stress and the implementation of the artificial cultivation techniques on mulberry photosynthetic characteristics. However, few studies on the effect of mineral nutrient elements, especially N, P and K with the application on the photosynthetic physiology of the mulberry have been reported. With the development and application of the photosynthetic detector in China, domestic and foreign scholars have on in-depth and extensively researched the impact of the different fertilization treatments on crop photosynthetic characteristics. Therefore, in this study, starting from the photosynthetic physiology, to explore the mulberry leaf photosynthetic characteristics and the effect of different fertilization treatments on the regulation of photosynthesis of mulberry, using Li-6400xt portable photosynthesis system, through the in vivo determination, using summer cutting pruning, perennial test Mulberry Sichuan826mulberry varieties as test materials, the relationship between the NPK fertilizer application and the mulberry function leaf chlorophyll content, leaf area index, net photosynthetic rate, stomatal conductance, intercellular CO2concentration, transpiration rate was studied. The results shew that with the growth and development of mulberry, spring mulberry leaf chlorophyll content (Chla+b), stomatal conductance (Cond) gradually increased with the advancement of the growth period, showing a trend of first increase then decrease in autumn; net photosynthetic rate (Pn) show a trend of first increase then decrease in both spring and autumn; leaf area index (LAI), intercellular CO2concentration (Ci) and transpiration rate (Tr) show a trend of gradually increase in both spring and autumn. Different N, P, K fertilizer levels had a significant impact on mulberry photosynthetic indicators; appropriate N, P, and K fertilization amount can improve the LAI, of Chla+b and Pn, Cond, Tr of mulberry tree, while lack or excess fertilization reduce its photosynthetic capacity; the Ci of mulberry leaves without fertilizer was significantly higher than that of fertilization tree. Appropriate N, P and K application level N2P2K2(N600kg.hm-2,P2O5210kg.hm-2, K2O300kg.hm-2) can keep the mulberry function leaves suitable for photosynthetic state, and keep a long period of high photosynthetic rate. This study can provide a theoretical basis for high-quality and high-yield mulberry fields construction.3. Effects of N, P and K on the mulberry leaf protective enzyme activities and membrane lipid peroxidationPlant Stress Physiology is to study the physiological and biochemical changes and mechanisms of plants under stress conditions. The main adversities with important impacts on plant include Water deficit, low temperature, high temperature, salinity, environmental pollution and other physical and chemical adversities. In addition, the mineral nutrient elements applied improperly will cause nutrient stress on crop. Nutrient stress causes reactive oxygen metabolic disorders, cell membrane structure destroyed in plants. As the protective enzymes in organisms, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) play a certain role in removing harmful free radicals generated under stress condition. Malondialdehyde (MDA) is a plasma membrane oxidation product, and the level of its content reflects the plasma membrane peroxidation degree. In recent years, many studies have been reported on mulberry fertilization; however, no study has been reported on effects of the fertilizer on protective enzyme activities and membrane lipid peroxidation. Therefore, in this paper, using mulberry as materials, the effects of N, P, K fertilizer ration on the protective enzyme activities and membrane lipid peroxidation of the functional leaf of mulberry were systematically studied to reveal the mechanism of mulberry leaf senescence and provide a theoretical basis for improving the quality of mulberry leaves, and extending the functional period of mulberry leaf. The results show that with the growth and development of mulberry in spring, soluble protein content, superoxide dismutase, catalase activity, peroxidase activity and malondialdehyde content increased in mulberry with different treatments; with the growth and development of mulberry in autumn, soluble protein content, superoxide dismutase, catalase activity and peroxidase activity firstly increased and decreased later in mulberry with different treatments, while malondialdehyde content gradually increased; throughout the growing period, with the increase of fertilization amount in the same treatment, soluble protein content, superoxide dismutase, catalase activity and peroxidase activity all significantly increased, while malondialdehyde content significantly decreased, each reach the best point at level2(N2P2K2). Therefore, scientific N, P, K ratio and application amount (N2P2K2:600kg/hm2N,210kg/hm2P2O5,300kg/hm2K2O) can significantly improve the mulberry leaves in the activities of protective enzymes, reduce membrane lipid peroxidation and effectively delay the mulberry leaf senescence.4. The impact of balanced fertilization on the mulberry nutrient uptake and distributionN, P and K are the three fertilising elements essential for plant growth and development, N, P and K nutrient content, the absorbing amount and their distribution and other nutritional characters of plants are the basis for scientific fertilization. Most researches show that N, P, K and its combined application can significantly promote the growth and development of crops, improve the nutrient content in plant and increase their nutrient uptake and accumulation. Few studies on the effects of fertilization on the N, P and K contents and nutrient uptake amount of mulberry have been reported. Studies in China have focused on the pot experiments, while field test is rare. Furthermore, the previously reports did not have enough fertilization level design; therefore, it was difficult to draw accurate conclusions. In this paper, the summer cutting mulberry trees were used as research materials to explore the law the effects of N, P and K on the mulberry nutrient absorption and distribution. Through field trials, the effects of different fertilization treatments of N, P and K on the N, P and K contents and absorbing amount and distribution in the different parts of mulberry trees such as leaves, branches, shoots, etc, in spring and autumn were studied. The results show that, in the aspect of the fertilizer types, the absorbing amount in different parts performs the same as N>K>P; in the aspect of nutrition distribution, spring leaves>shoots> branches, autumn leaves> branches, leaves> branches although the year. Different amount of N, P and K significantly affected the N, P and K contents and the absorption and distribution of nutrition of mulberry leaves, branches and shoots in spring and autumn; the nutrient content and absorption at level2and3of N, P and K fertilization were significantly higher than those of level1and level0. Properly increase in N, P and K fertilizer application will increase the N, P and K contents and nutrition absorption in each part of the mulberry trees.In spring, with the increase of N application, shoots and leaves grew vigorously, which inhibited the growth and N absorption of branches, the N contents in branches performed as N2>N3>N1>N0. As the effect of N fertilizer on spring branches'dry matter accumulation was N2>N1>NO>N3, the spring branches' N absorption performed as N2>N1>N3>N0; with the increase in the amount of nitrogen fertilizer, nitrogen content of spring shoots, autumn branches and mulberry leaf increased, and overall performance as N3>N2>N1>N0; dry matter accumulation in spring shoots and autumn branches increased with the increase in the amount of nitrogen fertilizer, and nitrogen uptake also shew N3>N2>N1>N0; Mulberry leaf dry matter accumulation was maximum (N2>N3>N1>N0) at levels2, therefore its nitrogen uptake of the overall performance of N2>N3>N1>N0. The content and absorption amount of P in spring mulberry branches, the shoot content increased with the increase of phosphate fertilization and its performance of P3>P2>P1>P0; The P content and absorption of Pin the summer cutting mulberry branches in autumn firstly increased and decreased later with the increase of P fertilization with the performance of P2>P3>P1> P0; the P content and absorption of mulberry leaves in spring and autumn performaned as P2>P1>P3>P0and P1>P2>P3>P0respectively, which indicated that proper amount of P fertilizer improved the growth of mulberry leaves, while excess P fertilizer inhibited the growth of mulberry leaves, reducing the accumulation of dry matter and subsequently affecting the absorption of P. The K content and absorption amount in mulberry trees firstly increased and decreased later with the increase of K fertilization, and reached maximum at K2level, with the performance of K2>K3>K1>K0. All through the year, the K content in mulberry leaves increased with the increase of K fertilization only in spring.5. Effects of balanced fertilization on mulberry leaf quality and its active ingredient contentWe have systematically investigated the nutrient management conditions of mulberry in the Sichuan hills sericulture main producing areas. The results shew that the site conditions of Sichuan mulberry were poor, and its soil fertility was low. The unscientific usage of fertilizer resulted in soil nutrient deficiency and unbalanced. The inefficient usage of N and P fertilizer resulted in the low yield and quality of mulberry leaves, which severely inhibited the development of sericulture production in Sichuan Province. Previous studies mainly focused on the effects of different fertilizers on the leave yield and quality, cocoon yield and quality. However, no study on the mulberry leaves quality, especially the yield of mulberry leaves and its contents of flavonoids and1-deoxynojirimycin and other biologically active components using balance fertilization techniques has been reported. The results of modern medical research show that the mulberry leaves are rich in1-deoxynojirimycin (DNJ) and flavonoid and other active compounds, presenting hypoglycemic, anti-oxidation, anti-aging and other health and therapeutic efficacy. In this paper, summer cutting mulberry trees were used as research materials to explore the law of effects of N, P and K on the quality of mulberry trees and the formation of main active compounds. The effects of different N, P, K fertilization treatments on the contents and yield of flavonoids,1-deoxynojirimycin, crude protein and soluble sugar in spring and autumn mulberry leaves were studied using the "3414" balance fertilization method. The results shew thatthe contents of determination indicators significantly increased with the increase of single N, P, K fertilizers application, while excess application resulted in no significantly variation or significantly decrease of the contents. By further fitting the determination indicators production in mulberry leaves and N, P, K fertilizers response equations, the highest yield and related recommended fertilization parameters were obtained. The highest yield and recommended fertilization parameters of flavonoids,1-deoxynojirimycin, crude protein, soluble sugar were (147.90Kg/hm2;675.96Kg/hm2N,326.49Kg/hm2 P2O5,462.90Kg/hm2K2O),(13.55Kg/hm2;720.93Kg/hm2N,225.11Kg/hm2P2O5,323.63Kg/hm2K2O),(1816.83Kg/hm2;718.46Kg/hm2N,220.11Kg/hm2P2O5,305.23Kg/hm2K2O),(1042.65Kg/hm2;666.54Kg/hm2N,204.41Kg/hm2P2O5,243.18Kg/hm2K2O) respectively. This experiment may provide a theoretical reference and guidance for the Sichuan region of great efforts to develop the comprehensive development of mulberry and the establishment of high quality and yield mulberries with specific target products.6. The establishment of mathematical models of hilly region mulberry balanced fertilization in Sichuan ProvinceFertilization model is one of the core content of the fertilizer technology. Fertilizer response function model is a statistical model, which can reveal the interaction of diverse fertilizers and theoretically calculate the highest and best fertilization amount when reaching the highest and best yield and evaluate the interaction between the fertilizers."3414" fertilizer trial design is one of the best quadratic regression D-optimal designs. The "3414" design program not only has the regress optimal design's advantages of less process and high efficiency, but also meets the professional requirements of the fertilizer test and fertilization decisions. In this study, according to the problem exists in the hilly the sericulture main producing areas of Mulberry nutrient management process in Sichuan Province, to increase leaf yield and production efficiency per unit area of mulberry, using the modern fertilizers quadratic regression "3414" design program, the regress relationships between mulberry leaves and N, P, K were simulated with the leaf yield as the objective function and selecting the fertilization level of fertilizer elements N, P, K as regulatory factors. Through trial studies,3kinds of7varieties N, P, K fertilizer response functions were obtained. The fertilizer factors weights of various types of function to obtain the best mulberry leaf yield performed as K>PK>P>NPK>NK>N>NP, and the best of output to input ratio fertilizer factor weights expressed as K>PK>NPK>P>NK>NP>N. Of the three kinds of functions, the ternary quadratic fertilizer effect function (Y=20313+0.25X1+43.48X2+34.47X3-0.01X12-0.14X22-0.06X32+0.05X1X2+0.02X1X3-0.07X2X3, X1,X2,X3are N, P, K fertilizers effect factors) was full-factor model, which could be used as recommending fertilization program of mulberry. The effect of single factor analysis showed that the K fertilizer presented the greatest impact on the production of mulberry leaf yield. Therefore, in all simulation functions, quadratic fertilization effect equation of K fertilizer factor (Y=25002.27+44.728X3-0.084X32) obtained the highest ratio of best yield to input. The usage of the optimal fertilization of600kg/hm2N,210kg/hm2P2O5,254.33kg/hm2K2O can obtain the best economy of mulberry leaf yield of30945.00kg/hm2with the fertilization input of4403.65Yuan/hm2; and the ratio of production to input reached to17.57. After proved by production practice, the best fertilization program may provide a reference for the construction of high-yield mulberry fields of the hilly sericulture area in Sichuan Province.