磷肥用量对石灰性紫色土壤油麦菜产量、品质和养分形态的影响

Effects of phosphate fertilizer on yield,quality and plant nutrient form in lettuce in‘calcareous purple'soil

通过大田试验研究了两种磷含量石灰性紫色菜园土不同磷（0,45,90,135,180,270kg/hm^2）施肥水平对油麦菜产量、品质和养分形态的影响.结果表明,两个试验点施用磷肥均能显著提高油麦菜产量,增产率分别为9.5%～26.7%和8.1%～21.3%,均以P4（180kgP2O5/hm^2）最高,且施用磷肥对油麦菜的增产效果以试验点1（含湖村）优于试验点2（含金村）.磷肥施用量与油麦菜产量存在极显著的二次回归关系,试验点1油麦菜最高产量和经济最佳产量施磷量为219和215kg/hm^2,试验点2为195和191kg/hm^2.试验点1各处理维生素C、氨基酸和可溶性糖含量均呈下降趋势,以P2 降幅最大（达15.8%,27.8%和14.0%）,而硝酸盐含量呈上升趋势;试验点2各处理油麦菜维生素C 含量呈上升趋势,以P4、P5 增幅较大（为6.3%和20.4%）,氨基酸和可溶性糖含量呈降低趋势,以P4 降幅最大（为35.0%和8.3%）,硝酸盐含量呈下降趋势,以P2 降幅最大（6.9%）.两个试验点油麦菜全氮磷含量均以P4 最高,氮磷钾养分形态均分别以蛋白氮、非蛋白磷、非蛋白钾为主.各养分以钾素与油麦菜品质间的关系更为密切,试验点1油麦菜全钾含量与维生素C、氨基酸含量均呈显著正相关,而试验点2油麦菜蛋白钾含量与维生素C 含量呈显著负相关.两个试验点油麦菜磷素利用率均以P1 最高（8.14% 和9.38%）,P4 次之（4.64%和7.42%）.综合油麦菜各指标效应认为,在本研究区域有效磷（30～60mg/kg）缺乏的石灰性紫色菜园土壤环境条件下,推荐施磷量为180kgP2O5/hm^2.

Field experiments were conducted to examine lettuce production in‘calcareous purple'soils with six different phosphate( P) levels( 0,45,90,135,180 and 270 kg / ha P2O5) at two sites( 1. Hanhu village and 2. Hanjin village) in order to investigate effects of the different P fertilizer levels on yield,quality and plant nutrient form in lettuce.Yields of lettuce for the two sites were significantly increased( 9. 5%- 26. 7% and 8. 1%- 21. 3%,respectively) by application of P fertilizer and maximum yields were obtained from the P4treatment( 180 kg P2O5/ ha). There was a significant quadratic regression relationship between P fertilizer rates and yields of lettuce,the maximum yield and economic optimum application rates were,respectively,219 and 215 kg / ha( P2O5) for site No. 1,and 195 and 191 kg /ha for experimental site No. 2. Contents of vitamin C,amino acids and soluble sugar of lettuce were reduced in all treatments and in the P2 treatment were decreased,respectively,by 15. 8%,27. 8% and 14. 0% for site No. 1. At site No. 2,nitrate contents of the lettuce were decreased and vitamin C contents were improved in all treatments and were increased by6. 3% and 20. 4% in P4 and P5treatments,respectively. Levels of amino acids and soluble sugar were reduced in all treatments and for the P4 treatment were decreased by 35. 0% and 8. 3%,respectively. Nitrate contents were reduced,with the P2 treatment decreased by 6. 9%. The highest contents of total-N and total-P of lettuce were achieved in the P4 treatment for both experimental sites. With respect to forms of plant nutrients: N,P and K were mainly present as protein-N,non-protein-P and non-protein-K,respectively in the lettuce. K levels correlated more closely with lettuce quality than did N and P levels. Total-K showed a significantly positive correlation with vitamin C and amino acid levels for site No. 1,but protein-K showed a negative correlation with vitamin C for site No. 2. The maximum P use efficiency was obtained from the P1treatment( 8. 14% and 9. 38%,respectively),followed by the P4treatment( 4. 64% and 7. 42%,respectively),for the two experimental sites. Overall,from this study,the recommended application rate of P fertilizer for P-deficient ‘calcareous purple soil'used for vegetable production was 180 kg / ha( P2O5) under these conditions.