15N tracer elements were used to study the effects of fertilization either using a fertilizer applicator or broadcast application in the radial ditch(CK) on nitrogen absorption,utilization,and distribution,and fruit quality and yield of five-year-old trees of the early-maturing peach 'Yuhualu' and ten-year-old trees of the late-maturing cultivar 'Chinese Peach'.After fertilization with the fertilizer applicator,the percentage nitrogen derived from fertilizer(Ndff%) of new shoot leaves increased significantly from the new shoot growth stage and throughout the growing season the Ndff% and chlorophyll content of new shoot leaves were maintained at high levels,while the growth rate of new shoots was accelerated significantly at the new shoot growth stage.After the fruits were harvested,the Ndff% of the fruit flesh and stone were 3.64 and 4.73 times higher,respectively,than those of CK.The nitrogen absorptivity of the plant was 20.35% at the end of the growing season,which increased 5.87 percentage points than that of CK.These results indicated nitrogen was absorbed more quickly and transported to newly developing organs following fertilization with the fertilizer applicator and,in addition,nitrogen utilization efficiency was significantly improved.After fertilization with the fertilizer applicator,the percentage residual nitrogen fertilizer was 49.33%,whereas with broadcast fertilization in the radial ditch,the residual nitrogen fertilizer was 50.46%;the difference between the two methods was not significant.Fertilization with the fertilizer applicator was beneficial to improve yield and the soluble solids content of peach fruit.Provided with 1000 kg/ha compound fertilizer applied with the fertilizer applicator each year,the soluble solids content of peach fruit was 14.14% and the fruit yield was 26780 kg/ha,respectively,an increase of 3.31 percentage points and 3525 kg/ha over that of CK(1250 kg/ha).

Five genotypes pakchoi〔Brassica campestris L. ssp. chinensis(L.)Makino var. communis Tsen et Lee〕including‘Suzhouqing’,‘Huangxinwu’,‘Piaoercai’,‘Kangre 605’and‘Nannongaijiaohuang’were selected. The genotypic variations of Zn tolerance and Zn accumulation were studied under 5 different zinc levels(0.43,100,200,400 and 800 mg·L-1)by pot experiment with sand culture in solar greenhouse. The results indicated that the shoot biomass of 5 varieties was slightly increased under different zinc levels. Only the root growth of‘Kangre 605’was inhibited under the highest Zn solution, while the roots of the other 4 genotypes were slightly affected. The root tolerance indexes of all the genotypes ranged from 0.82 to 1.90. So they showed very high tolerance to Zn stress. Comparatively, the tolerance of‘Kangre 605’was inferior. The Zn concentration and accumulation in different organs were increased greatly with enhancement of Zn level. The Zn content in roots was the highest. However, Zn accumulation in it was the lowest. More than 60 % Zinc absorbed by roots was transferred to up ground. The redundant zinc absorbed by‘Suzhouqing’,‘Huangxinwu’,‘Kangre 605’and‘Nannongaijiaohuang’was mostly stored in petioles, and leaves were primary storing organ in‘Piaoercai’. Comparatively, Suzhouqing's ability for accumulating Zn is the strongest. While‘Nannongaijaohuang’is the weakest, but it has very high translocation ability.

Nitric oxide(NO) serves as a bioactive molecule involved in antioxidant and anti-stress agent in tolerance responses to abiotic stress.A hydroponic experiment was conducted to investigate the effects of exogenous sodium nitroprusside(SNP),a NO donor,on photosynthetic characteristics,bioluminescence intensity,chlorophyll and mineral element contents in tomato(Lycopersicon esculentum Mill.) plants treated with 50 μmol/L CuCl2.The application of 100 μmol/L SNP significantly increased chlorophyll contents,net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs),copper(Cu),calcium(Ca),iron(Fe),zinc(Zn),manganese(Mn) contents in leaves and copper(Cu),potassium(K),iron(Fe),zinc(Zn) contents in roots;and dramatically decreased ultraweak luminescence intensity,fluorescence intensity,phosphorescence intensity and calcium(Ca) content in roots induced by CuCl2.While the mitigate response of SNP to Cu stress were inhibited by addition of hemoglobin(a NO scavenger).No significant difference on photosynthetic,bioluminescent characteristics and mineral element contents in tomato was observed by the application of sodium nitrate or nitrite(the decomposition products of NO or its donor SNP) or sodium ferrocyanide(an analog of SNP) which did not release NO.We concluded that exogenous NO could improve photosynthetic characteristics,decrease ultraweak luminescence intensity,fluorescence intensity,phosphorescence intensity,maintain the mineral nutrition balance,alleviate the inhibition of tomato by copper stress.

Two genotypes non-heading Chinese cabbage suzhouqing and nannongaijiaohuang were selected as materials. The chemical bound forms of Zn and root exudation under high Zn stress were studied by hydroponic experiment. The main results were as following: Under normal Zn level, the chemical forms of Zn in three organs were diverse in deferent organs between genotypes. HAc extractable-Zn, ethanol extractable-Zn and NaCl-extractable Zn were separately dominant in roots, petioles and leaves. Only four molecular weight organic acid could be detected. Under Zn stress(13 mg/L and 52 mg/L) NaCl-extractable Zn became a predominant form. Oxalic acid, tartaric acid, malic acid, lactic acid, acetic acid, citric acid and amber acid were all detected. So we speculated that NaCl-extractable Zn and organic acid were related to Zn tolerance. Some organic ligands like proteins and pectinate which could form compound body with Zn were beneficial for alleviating zinc toxicity. And the variance of organic acid enhanced the adaptability to Zn stress by chelation.