Effect Of Interaction Between Soil Fertility And Irrigation On Grain Yield And Quality Of Wheat And Its Physiological Basis

In order to investigate the effect of the inter-action of soil fertility and irrigation on the yield and quantity of wheat, to provide a theoretical basis for research of reducing the application of water and fertilizers and cultivation technique for high yield, the research was initiated from 2004 to 2006, at the Experiment station of Shandong Agriculture University in pot culture method. Four cultivars were selected to study, viz. Jimai20, Zimai12 and PH1521 with strong gluten and Lumai21 with medium gluten. The coupling effect of soil fertility and irrigation on the changes of population, yield and its structures, photosynthetic feature, metabolism of carbon and nitrogen, grain quality and water utility efficiency were studied. The nitrogen balance and nitrogen fertilizer utility efficiency were also studied by 15N isotope tracing technique. The main results were as follow.1. The yield of winter wheat was improved with the increasing of soil fertility and irrigation quality. But the sensitivity of two factors was different. The result of mathematical analysis demonstrated that, the yield of two cultivars was very significantly affected by soil fertility, but Jimai20 was the only one whose yield was significantly affected by water factor. The comparation of grain yield of two cultivars between six treatments was that, treatment 2>treatment 4>treatment 1>treatment 3>treatment 6>treatment 5. Compared with the treatment of medium fertility and full irrigation, the yield of treatment of high fertility and limited irrigation was only decreased from 0.06%~5.3%. On the contrary, compared with the treatment of low fertility and full irrigation, the yield of the treatment of medium fertility and full irrigation increased by 12.86%~21.98%. The result showed that high soil fertility is the basis of water-saving and high-yield wheat production.The average yield result of two water treatment was studied as that, the yield of high fertility of Lumai21 increased by 5.06% and 38.27% compared with medium fertility and low fertility, and the medium fertility increased by 31.61% compared with low fertility. The average yield of three fertility treatment showed that, the yield of full irrigation increased by 7.09% compared with limited irrigation. The yield of high fertility of Jimai20 increased by 12.04% and 46.25% compared with medium fertility and low fertility, the yield of full irrigation increased by 17.18% compared with limited irrigation. The result showed that soil fertility was the main factor which affect yield on the condition of high fertility, irrigation was minor factor. There was evident compensatory effect on irrigation and soil fertility on the condition of low fertility. The reaction of Jimai20′s yield to water and fertility was more sensitive than Lumai21.2. The photosynthetic rate and transform efficiency and potential activity of light-energy in chlorophy PSⅡsystem of flag leaf after flowering were promoted with increased soil fertility and irrigation quantity. But the effect of fertility on Pn,ФPSⅡa nd Fv/Fm was more sensitive than irrigation. Though Pn decreased gradually during the growth stage, but the time which Pn andФPSⅡbegin to drop was significantly delayed on the condition of high fertility than which on low fertility. High photosynthetic rate was maintained on the condition of high fertility with limited irrigation quantity. The variation tendency of daily change of net photosynthetic rate(Pn) was showed as that: high fertility>medium fertility>low fertility, full irrigation>limited irrigation at same soil fertility. There was no significant difference between the treatment of high fertility with limited irrigation and the treatment of medium fertility with full irrigation. The result showed that coupling effect of appropriate soil fertility and irrigation has regulation effect on Pn of flag leaf. The photosynthetic active duration of flag leaves of Jimai20 was longer than Lumai21, and its average photosynthetic rate is higher 3.21%~34.84% than Lumai21.3. Sugar content in flag leaf and soluble sugar content in stem increased with the increase of soil fertility. And between irrigation treatments there were no significant difference from blossoming to14days after anthesis, and the treatment of full irrigation is less higher than the treatment of limited irrigation 14 days after blossoming. Among these treatments, the sugar content in flag leaf and soluble sugar content showed as that, the treatment of high fertility with limited irrigation> the treatment of medium fertility with full irrigation, the treatment of medium fertility with limited irrigation> the treatment of low fertility with full irrigation. The activity of NR and GS increased with the increase of soil fertility and it promoted the activity of nitrate reductase, so grain protein content and yield of protein increased significantly. And irrigation had no significant effect on the activity of NR and GS from blossoming to14days after anthesis, and the treatment of full irrigation is less higher than the treatment of limited irrigation 14 days after blossoming. For the content of water carbohydrate increased on the condition of full irrigation, its protein content was less than limited irrigation, however, its yield of protein was higher. The content of three kind of protein components increased with fertility increased, monomeric protein content and soluble gluteinin could be raised by irrigation, but insoluble glutenin content decreased. Amylose content and ratio of amylopectin and amylase increased with the increase of soil fertility and irrigation quantity, but the change of amylopectin content was not evident.4. Soil fertility and irrigation had great effect on nitrogen fertilizer utility efficiency and water utility efficiency. The amount of total N accumulated in wheat plant and which derived from soil increased with increase in soil fertility. Nitrogen uptake proportion from soil was showed as that, high fertility>medium fertility>low fertility, while nitrogen uptake proportion from fertilizer showed the reverse tendency. Which showed it could effectively reduce dependence on nitrogen fertilizer with the increase of soil fertility, the proportion distribution in grain decreased significantly at the same time. Nitrogen fertilizer utility efficiency was as follows: medium fertility>high fertility>low fertility, the loss efficiency was low fertility >high fertility >medium fertility and there were no significant difference in residue rate. Irrigation quantity increasing could enhance the capacity to absorb nitrogen on different fertility, it also increased loss efficiency of fertilizer nitrogen, decreased residue rate in soil and distribution rate in grain. The absorption efficiency of nitrogen fertilizer was varied from 39.08% to 53.08% in different treatment, N remained in soil ranged in 21.80%~33.59% and losses in 18.81%~34.62%. Nitrogen uptake proportion from fertilizer was varied from 29.88%~47.55%.Water utility efficiency increased significantly with the increase of soil fertility. The water utility efficiency of high fertility and medium fertility increased by 37.36% and 23.15% compared with low fertility, high fertility increased by 11.53% compared with medium fertility. And water utility efficiency of limited irrigation increased by 14.42% compared with full irrigation.5. The result of single-factor experiment on soil fertility suggested as that: Grain protein content and protein yield of different wheat could be improved significantly with the increase of soil fertility. In the mean time, zeleny sedimentation volume and wet gluten content increased significantly, dough development time and stability time extended significantly too. Processing quality of different types of wheat cultivars was not only controlled by their own genotype, but also influenced by the impact of soil fertility. There was obvious difference between cultivars with strong gluten and cultivars with medium gluten in RVA parameter. High soil fertility base could prolong peak viscosity, through viscosity, final viscosity, peak time, setback and pasting temperature of Zimai12 and PH1521. But Lumai21 went in the opposite direction. These facts tell that the effect of soil fertility base on wheat quality is different because of different varieties.