重庆柑橘园钙素营养研究

研究重庆柑橘园的钙素营养现状，为合理管理柑橘园钙素营养提供科学依据。通过对重庆市218个柑橘园土壤及叶片的采样分析和调查研究，结果表明，重庆市柑橘园土壤钙含量丰富，平均为3316.7 mg/kg，其中49.5%的土壤有效钙含量较高（＞3000 mg/kg），缺钙的土壤（1000 mg/kg）仅占 17.9%；但是柑橘叶片钙含量不足或缺乏（30 g/kg）的柑橘园占38.3%，叶片钙含量过高(70 g/kg)的仅占0.3%；叶片钙含量不足的样本数明显高于缺钙土壤；土壤钙与柑橘叶片钙含量的关系因土壤钙含量的不同而存在差异，当土壤有效钙含量低 (1000 mg/kg)时，叶片钙含量也低(30 g/kg)，叶片钙含量随土壤有效钙含量的增加而升高，二者呈极显著正相关 y=0.0151 x +16.459 (r =0.608**, n=39， r 0.01=0.408)；当土壤有效钙含量呈高量或过量时，二者的相关关系不显著，叶片缺乏和过量现象并存。缺钙土壤和钙含量高的土壤上都可能出现叶片缺钙现象，在管理柑橘园钙素营养时，应综合分析影响钙素营养的各种因素，选择适宜的钙肥种类、施钙方式和时期，结合土壤的供钙能力、柑橘种类及砧木、营养元素之间的平衡等，制定出合理的管理模式。

Study on calcium nutrition in Chongqing citrus orchards

Status of calcium nutrition in Chongqing citrus orchards was studied to propose comprehensive management measures for Ca nutrition of citrus orchards. Ca contents in soils and leaves of 218 citrus orchards were studied. The results show that there is abundant soil Ca in Chongqing citrus orchards with an average of 3316.7 mg/kg, and soil available Ca contents in 49.5% citrus orchards exceed 3000 mg/kg belonging to excessive range and those in 17.9% citrus orchards are less than 1000 mg/kg which are in the range of deficiency. The Ca contents in leaves of 38.3% citrus orchards are in the range of deficiency（30 g/kg）, and those of 0.3% citrus orchards exceed 70 g/kg which is in excessive range. This indicates that soils with abundant Ca do not ensure the need of citrus trees to Ca nutrition. The relationship of Ca contents in soils with those in citrus leaves is not certain because of the change of Ca contents in soils. When the content of available Ca in soils is low, Ca concentrations in leaves are increased with the increase of soil Ca contents and there is a significant positive correlation y=0.0151 x +16.459 (r=0.608**, n=39，r0.01=0.408). When soil Ca content is in high or very high range, it is not correlated with Ca contents in leaves, and leaves with both deficient and excessive contents are found. As a result, not only Ca deficiency in soils could lead Ca deficiency in leaves, but also excessive Ca in soils could cause Ca deficiency in leaves. When managing Ca nutrition in citrus orchards, every factor influencing Ca availability should be considered, which includes types and application methods of Ca fertilizers, phases, the ability of soil to supply Ca, citrus cultivars, rootstocks, the balance of main nutritional elements, and then propose rational management measures of Ca nutrition.