| Zinc is an essential micronutrient for plant and animal, it enters into to the food chain through plant, and it enters the diets of human being directly or through animal indirectly, so the balance of nutrition and the health of buman being is affected by zinc. Zinc in wheat grain is the most important source of zinc nutrition to people whose stape food mainly depends on wheat food. So zinc deficiency of wheat grain can lead to zinc deficiency of sensitive people easily. And the most useful approach to solve this problem is to increase the zinc concentration of wheat grain, application of zinc fertilizer and screening the wheat genotypes with high zinc efficiency at present. This study was to investigate effects of calcacium carbonate on the availability of soil zinc in calcareous soil, and the effects of zinc fertilization on the effects of zinc concentration and bioavailability of different types, the wheat genotypes with high zinc efficiency or with better response on residual effect in the soil were expected to be screened to improve the nutrition qulity of wheat. The main results of this study are as follows:(1) High concentration calcium carbonate in calcareous soils usually limits plant Zn uptake. In this paper, a solution culture experimentwas conducted to study the effects of CaCO3 addition with or no Zn supply on the growth and Zn up take of three genotypes winter wheat seedlings. The results showed that Zn supply or CaCO3 addition had no significant effects on seedlings biomass and root/canopy ratio, and there was no significant difference among the three genotypes. CaCO3 addition led to leaf chlorosis. No matter with or no Zn supply, CaCO3 addition had no significant effects on the Zn concentration and accumulation in wheat root, stem, and leaf. Zn supply increased the Zn concentration in Yuanfeng 998, Zhongyu 6, and Xiaoyan 22 by 80.0%, 104.8% and 139.6%, respectively. For Yuanfeng 998, a sensitive genotype to Zn-deficiency, the increment of Zn concentration and accumulation was much lower than that of Zhongyu 6 and Xiaoyan 22, non-sensitive genotypes to Zn-deficiency. Zn supply or CaCO3 addition had no significant effects on the P content in root, stem, and leaf, but the corresponding P content of Yuanfeng 998 was obviously lower than that of the other two genotypes. Zn supply greatly decreased the P/Zn ratio in root, stem and leaf, and CaCO3 addition also showed the same tendency. Under Zn-deficiency, CaCO3 addition caused leaf chlorosis, but did not decrease wheat plant Zn up take. In conclusion, at least under solution culture condition, high concentration calcium carbonate had no obvious inhibitory effect on plant zinc uptake, and whether this situation was true in calcareous soils is worthy to be further investigated.(2) High content of calcium carbonate in calcareous soil is one of major factors which cause zinc deficiency of crops. In this research, varied amounts of calcium carbonate was added artificially to the calcareous soil and different levels of calcium carbonate was formed to investigate the effect of calcium carbonate on available zinc content in soil, the growth situation as well as Zn, Fe nutrition of two different wheat genotypes (Yuanfeng 998, Zhongyu 6). The obtained results showed that, the available Zn content of soil increased over 3 times at harvest from the initial 0.65 mg/kg at beginning of culture when adding Zn fertilizer (40 mg/kg) to soil; high content of calcium carbonate decreased the availability of zinc, and only about 1.3% of zinc added was taken up by wheat plants during the culture period, and most of newly added available zinc was transformed into unavailable form. The uptake of Fe by wheat plants was inhibited significantly when calcium carbonate content was high as 111.8 g/kg, however, the inhibition would become weaker when adding more calcium carbonate to soil. There existed obvious differences for their growth between two tested wheat genotypes, the ratio of root/shoot and tillering number of Zhongyu 6 was higher significantly than that of Yuanfeng 998. The Zn concentration and content of wheat plants was greatly increased following Zn application, the Zn concentration of root was inhibited when calcium carbonate was added to 111.8 g/kg, whereas it was not obvious for other parts of wheat plants. In addition, the Fe concentration of leaf and translocation efficiency was increased with Zn application.(3) 10 genotypes which were planted in Shaanxi Guanzhong Plain Area mainly were chosen in this study, a field experiment was carried out on calcaous soil for two years in succession, Zn fertilizer was applied in the first year, no zinc fertilization in the second year, but nitrogen fertilization was conducted in the continouns two years. The soil zinc contents of different forms in 0-20 cm and 20-40 cm soil depths was determined before wheat sowing, the filling stage and maturity stage, respectively. The results obtained showed that the Zn concentration in wheat grain could be increased by zinc fertilization on calcareous soil in which had low level of available zinc contend. The available Zn content in topsoil could be increased by planting wheat, the content of EX-Zn, WBO-Zn, CARB-Zn and OXMn-Zn were all increased by zinc fertilization, and these different forms of Zn could be utilized by wheat plants in the next year, furthermore, the contents of these various forms of Zn decreased after the wheat harvest, only the content of MIN-Zn was higher in soil at Zn fertilization compared to no zinc fertilization, so the potential Zn source in the soil reduced, and the zinc fertilizer response was decreased, but the available Zn content was still in high level, so it is worth further studying the residual effect of Zn fertilizer applied on the growth of wheat in the years that followed; application of nitrogen fertilizer increased the absorbtion of Zn from soil to wheat, but the soil can compensate the consumption by itself; To the combination of nitrogen and Zn fertilization, application of nitrogen fertilizer increased the absorbtion of Zn to wheat, but decreased the available zinc content in the soil which increased by zinc fertilization at the same time.(4) Grain yield and Zn concentration of wheat grain were also investigated in the experiment to screen the genotypes with high Zn efficiency and with better response on residual effect in the soil. Zn fertilization increased grain yield to some extent, but there existed obvious genotypic difference of the increasing effects, among the 10 genotypes tested, Wunong148, Xinmai13 and Shanyou253 were three genotypes with high Zn efficiency; Xiza1, Shanyou225 and Xiaoyan22 were three genotypes with low Zn efficiency. The Zn concentration in grain of wheat geontypes with low Zn effiency could be increased by application of Zn fertilizer, but Zn fertilizer reponses of the genotypes with high Zn efficiency was not significant. Nitrogen fertilization was mainly beneficial for leaf growth, and it could increase the numbers of tillers and the chlorophyll SPAD values, the leaf chlorosis could be alleviated by application of nitrogen and zinc fertilizers. The result of this study showed that the range of translocation ratio of Zn to the grain was 46.3-64.8%, indicating that only about half of the total Zn taken up was translocated to the wheat grain, so a great deal of Zn remained in the shell, leaf and stem, reusing or increasing the translocation ratio could enhance the utilization of Zn fertilizer. The Zn translocation ratios of a majority of genotypes were increased by Zn fertilization, but the extent was not so large, and the zinc tranlocation ratios of a few of genotypes were decreased.
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