Effects Of Cadmium On Physiological Characteristics, Pod Yield And Seed Quality Of Peanut And The Regulation Of Calcium

This experiment was carried out in agronomy experimental station of Shandong Agricultural University in 2009-2010. Pot experiment was carried out to study the effects of cadmium stressing on peanut growth, physiological characteristics, yield and quality with peanut cultivars of Yuhua15 and XB023 and the effects on the physiological characteristics such as peanut growth, leaf chlorophyll content, photosynthetic rate and protective enzymes, as well as yield and quality in response to cadmium stressing after applying calcium fertilizer.The main research results were as follows:1. Effects of Cadmium on Physiological Characteristics of Peanut Cd could promote peanut vegetative growth, when the concentration of Cd was 1.00 mg/Kg and 2.50 mg/Kg, but could inhibit peanut vegetative growth, when the concentration of Cd was 7.50 mg/Kg and 15.0 mg/Kg. The critical density of XB023 resistant to Cd stressing was higher than that of Yuhua15. There was little influence on the chlorophyll content, photosynthetic rate and activity of protective enzymes at light Cd stressing (1.00 mg/Kg), and light Cd stressing didn't cause leaf senescing. Medium Cd stressing (2.50 mg/Kg) could obviously decreased the chlorophyll content, photosynthetic rate, but increased the activity of SOD, POD and CAT of Yuhua15 leaves, and didn't cause its leaf senescing, there was little influence on XB023 leaves at medium Cd stressing; Heavy Cd stressing (7.50 mg/Kg) decreased obviously the chlorophyll content, photosynthetic rate, increased the content of MDA of XB023 leaves, and caused its leaf senescing. Cd stressing could obviously decreased the activity of GS, GDH and GOGAT in two variety peanut leave. Applying Cadmium could increased the Cd content in peanut kernel, and the content was beyond the the national standards in peanuts for food(Cd content≤0.5mg/Kg). Light and medium Cd stressing could increased the Ca content in peanut leaf, stem and root, but heavy Cd stressing decreased the Ca content. Compared with two peanut varieties, the Ca cntent of XB023 was higher than that of Yuhua15 under cadmium stressing. 2. Effects of Cadmium on Pod Yield and Seed Quality of PeanutCd stressing decreased the yield of pod and kernel. The yield of Yuhua15 begins to decrease obviously when the concentration of Cd is 2.50 mg/Kg(medium Cd stressing), however, that of XB023 is 7.50 mg/Kg(heavy Cd stressing). Cd stressing could increase the content of soluble sugar, decrease the content of protein and fat, and reduce the ratio of oleic acid to linoleic acid(O/L) in Yuhua15 kernels; But Cd stressing could decrease the content of soluble sugar and fat, reduce the ratio of oleic acid to linoleic acid(O/L) in XB023 kernels. Light and medium Cd stressing could increase the content of protein and its components of Lys and Thr in peanut kernels. Compared with the XB023, Yuhua15 was Cd-sensitive cultivar and was injured easier under Cd stressing.3. The Regulatin of Calcium on Cadmium StressingApplication of Ca fertilizer could alleviate Cd impacts on the main stem height and branch length of peanut, which correspondingly increased the plant dry weight. Meanwhile, application of Ca fertilizer could alleviate Cd impacts on photosynthesis, which resulted in the increase of chlorophyll content, leaf photosynthetic rate, the activities of superoxide dismutase (SOD), peroxidase (POD), catlase (CAT) and the soluble protein content, and the decrease the content of malondialdeyde (MDA). So, the damage of peanut leaves induced by cadmium stress could be alleviated following application of Ca fertilizer. Application of Ca fertilizer increased both pod and kernel yield significantly with the increase of the pod weight, kernel rate and pod number per plant. Applying Ca fertilizer also increased the content of fat and protein of peanut kernel, and improved peanut kernel quality under cadmium stressing. Calcium fertilizer application could reduce the Cd content of kernels in both Yuhua15 and XB023, and the effect on the former cultivar was better than that on the latter one. It may be have different mechanisms for relieving the effects of cadmium stress on the two peanut varieties after appliying of Ca fertilizer. In terms of Yuhua 15, application of Ca fertilizer alleviated the damage caused by cadmium stress through reducing the plant's absorption of cadmium. On the XB023, that may be mainly through promoting plant vegetative growth and physiological characteristics.