荔枝、龙眼叶片中钾、钙、镁交互作用指标诊断标准的建立

植物钾、钙和镁3种养分之间存在交互作用,因此于2016~2019年在华南荔枝、龙眼主产区22个妃子笑荔枝园和8个储良龙眼园采集末次梢老熟期和果实膨大期叶片样本,测定叶片钾、钙、镁元素含量,用充足范围法研究荔枝、龙眼不同生育期的钾、钙、镁交互作用指标[K/Ca、K/Mg、K/(Ca+Mg)及Ca/Mg]的诊断标准值。结果表明,荔枝、龙眼叶片中钾、钙、镁交互作用指标在同一年份同一生育期的不同树之间、不同年份的同一生育期之间以及同一生长周期的不同生育期之间的差异均很大。但是,荔枝、龙眼高产群体的上述指标在不同年份的同一生育期的差异明显较小,而同一生长周期内不同生育期的差异仍为极显著(P<0.001),表明不同生育期应有不同的诊断标准。利用充足范围法,在荔枝叶片钾、钙、镁含量处于适宜范围的基础上,末次梢老熟期叶片K/Ca、K/Mg、K/(Ca+Mg)和Ca/Mg的适宜水平分别为3.1~4.2、4.1~4.9、1.8~2.2和1.15~1.54,果实膨大期的分别为0.51~0.92、1.63~2.81、0.40~0.73和2.62~3.66;在龙眼叶片3种养分含量为适宜水平的前提下,末次梢老熟期叶片K/Ca、K/Mg、K/(Ca+Mg)和Ca/Mg的适宜水平分别为1.55~2.06、8.9~10.2、1.32~1.69和5.1~6.2;果实膨大期的分别为0.46~0.61、5.3~7.5、0.42~0.56和11.1~12.8。上述指标为诊断荔枝、龙眼叶片中钾、钙、镁营养的平衡状态及指导3种养分的平衡施用提供了数据参考。

Establishment of diagnosis norms for interaction indexes of foliar K,Ca and Mg in litchi and longan

There are interactions among the three mutrients of plant,potassium(K),calcium(Ca) and magnesium(Mg). Twenty two typical litchi(cv. Feizixiao) orchards and 8 typical longan(cv. Chuliang),located in the main litchi and longan production regions of South China,were chosen in 2016 ~ 2019. A total of 193,186 and 159 litchi leaf samples were gathered at fruit swelling stage(FSS) of 2016,the terminal shoot maturing stage(TSMS) of 2016 and FFS of 2017,respectively. And,82,82,49 and 49 longan leaf samples were collected at TSMS of 2017,FSS of 2018,TSMS of 2018 and FSS of 2019,respectively. Foliar K,Ca and Mg concentrations in all samples were detected. Sufficiency range approach(SRA) was used to establish the diagnosis norms for interaction indexes of foliar K,Ca and Mg,which were characterized as K/Ca,K/Mg,K/(Ca+Mg) and Ca/Mg. The results showed that all the interaction indexes of foliar K,Ca and Mg significantly varied among trees at the same growth stage in the same year,between the same growth stages of different years and between various growth stages within the same growth cycle. The variation of the interaction indexes for the high yield population was obviously smaller than that for the whole population of both litchi and longan. However,significant difference was still observed for these indexes for various growth stages even in the same growth cycle(P<0.001).It indicated that different diagnosis norms of interaction indexes were required for various growth stages of litchi and longan.According to SRA,while foliar K,Ca and Mg were within the appropriate ranges,the optimal values of foliar K/Ca, K/Mg,K/(Ca+Mg) and Ca/Mg were recommended as 3.1 ~ 4.2,4.1 ~ 4.9,1.8 ~ 2.2 and 1.15 ~ 1.54 at TSMS,and 0.51 ~ 0.92,1.63 ~ 2.81,0.40 ~ 0.73 and 2.62 ~ 3.66 at FFS for litchi,respectively. Similarly,those values were suggested as 1.55 ~ 2.06,8.9 ~ 10.2,1.32 ~ 1.69 and 5.1 ~ 6.2 at TSMS,and 0.46 ~ 0.61,5.3 ~ 7.5,0.42 ~ 0.56 and 11.1 ~ 12.8 at FFS for longan,respedively. The above diagnosis norms provide quantitative reference for evaluation of the balance of foliar K,Ca and Mg and their balanced application for both litchi and longan.