荔枝叶片养分含量动态及不同比例钾、氮肥施用效应

【目的】探索荔枝叶片养分含量的周年变化规律及钾、氮肥不同施用比例对荔枝产量及其种植效益的影响，为荔枝生产中的施肥管理、营养调控与增产增效提供理论依据和实践指导。【方法】在大田栽培条件下，以1995年嫁接苗种植的国内主栽品种妃子笑为试材，设置钾、氮肥不同施用比例（K2O/N分别为0.6、0.8、1.0、1.2和1.4）5个处理，随机区组排列，于2009~2012年3个生长季在广东省惠州市荔枝主产区进行试验。在荔枝不同生育期定期采集荔枝叶片测定矿质元素含量，荔枝成熟时于田间按小区实收称重测产。【结果】荔枝叶片不同生育期的养分含量存在明显差异；在整个生育期，叶片养分含量的大小均表现为N﹥K﹥Ca﹥Mg﹥P﹥S﹥B﹥Zn﹥Mo；叶片K与Ca、Mg含量有极显著的负相关关系，K与Zn含量呈显著负相关，而Ca、Mg、Zn含量两两间呈显著正相关；叶片N与S、B含量呈显著负相关，而S与B呈极显著正相关；叶片P与Ca、Si含量呈显著负相关，而Ca与Si呈显著正相关。等氮基础上随着K2O/N比的提高，荔枝产量和种植效益均出现先升高后降低的规律；以K2O/N比例为1.0~1.2时荔枝产量最高、效益最好。【结论】在我国荔枝主产区以保持钾、氮肥养分施用比例（K2O∶N）为1.0~1.2为宜。

Dynamic changes of nutrition in litchi leaves and effects of potassium and nitrogen fertilization

【Objectives】Field experiment was conducted to determine the annual changes of element contents in litchi leaves and the effects of the nitrogen (N) and potassium (K) ratio on the yield and planting benefits of litchi，aiming to provide a theoretical basis and practical guidance for fertilization management, nutrition regulation in litchi production. 【Methods】The cultivar Feizixiao litchis，the main domestic grafted seedlings, were planted in 1995 and taken as tested material. Field experiments with different ratios of potassium over nitrogen (K2O/N: 0.6, 0.8, 1.0, 1.2 and 1.4) were conducted in the main litchi plant region of Guangdong in the 3 growth seasons from 2009 to 2012. Litchi leaves were collected periodically to measure the contents of mineral elements. When litchis are ripe, the actual yields of litchis were weighed in the field.【Results】The nutrient contents in litchi leaves vary significantly in different growing stages. During the whole growing period, the contents of nutrient elements in litchi leaves are in order of N K Ca Mg P S B Zn Mo. The K content is highly and negatively correlated with the contents of Ca and Mg, and significantly and negatively correlated with that of Zn. The contents of Ca, Mg and Zn are positively and significantly correlated with each other. The N content is negatively and significantly correlated with the those of S and B in leaves, and the contents of S and B show significant positive correlation with each other. The content of P exhibits significant negative correlation with Ca and Si, while the contents of Ca and Si are significantly and positively correlated with each other. Under the same N application rate, the yield and planting benefits of litchi are increased at first with the increase of ratio of K2O to N and then decreased. Litchi has the highest yield and benefit when the ratio of K2O to N ranges from 1.0 to 1.2. 【Conclusion】The ratio of K2O to N ranges from 1.0 to 1.2 is recommended for the main litchi production areas of China.