池塘植藕对沉积物养分和酶活性的影响

为了揭示池塘种植莲藕对沉积物养分吸收及其养分转化相关酶的作用效果，将基本情况完全相同的黄颡鱼养殖池塘分为植藕组（Tf）和非植藕组（CK），观察两组池塘在黄颡鱼苗种培育过程沉积物中养分和4种酶（脲酶、磷酸酶、蛋白酶、蔗糖酶）活性的变化特征。结果表明，与CK相比，Tf沉积物中的TN、NH4+—N和NO3-—N在莲藕苗期后均显著降低，在莲藕休眠期分别降低了8.5%、54.1%和52.7%，其中NH4+—N减少是沉积物中TN降低的主要原因；从莲藕苗期至花果期TP明显下降，最大降幅达22.6%；苗期后有机质开始显著降低，休眠期相较未植藕池塘降低8.4%。对两组池塘而言，沉积物的酶活性均呈现先增加后降低的变化趋势，Tf沉积物中4种酶的平均活性均高于CK，酶活性的差异在莲藕苗期和休眠期达显著水平（P < 0.5）。分析表明，4种酶之间存在着显著正相关关系（P< 0.5），脲酶、磷酸酶和蔗糖酶活性与沉积物中NH4+—N的含量呈显著负相关，蛋白酶活性与沉积物中NO3-—N的含量呈显著正相关。

Effects of Planting Lotus Root on Sediment Nutrients and Enzyme Activity in a Culture Pond

In this study, lotus (Nelumbo nucifera) was planted in a yellow catfish (Pelteobagrus fulvidraco) culture pond to construct a symbiotic system. We explored the effects of lotus root (Nelumbo nucifera) on the removal of nutrients from fishpond sediments and on the activity of enzymes involved with nutrient conversion. Two aquaculture ponds (20 m × 22 m) with yellow catfish were set with the same basic conditions: (1) a treatment pond (Tl) planted with lotus and (2) a control pond (CK) with no lotus. On May 20 2020, lotus roots were planted in the treatment pond and on July 28 yellow catfish fry were released to both ponds. The sediment of both ponds was sampled on May 10 (before lotus was planted) and June 11, July 18, August 22, October 1 and November 1 (after pond was dormant) to include the different growth phases of lotus. The sediment samples were analyzed for physicochemical parameters and the activities of four soil enzymes (urease, phosphatase, protease, sucrase). Changes in sediment nutrient levels and enzyme activity were then monitored as the yellow catfish fry and lotus grew. After the lotus grew past the seedling stage, nutrient concentrations in the T1 sediment were significantly lower than in the CK sediment. After the ponds reached the dormant stage, TN was lower in T1 by 8.5%, NH+4-N by 54.1% and NO-3-N by 52.7%. The lower TN content in T1 sediment was due primarily to the lower NH+4-N. The TP content in sediments of Tl decreased significantly as the lotus grew from the seedling stage to the flowering stage, with a maximum reduction of 22.6%. After the seedling stage, the content of organic matter in the sediment decreased significantly, by 8.4% when the ponds had reached the dormant stage. In both ponds, the sediment enzyme activity increased initially and then decreased. The averages activities of the four enzymes in Tl sediment were all higher than those in CK sediment. The differences in enzyme activity increased through the growing season and were significant by the time the pond reached the dormant stage (P<0.05). Correlation analysis showed (1) a significant positive correlation among the activities of the four enzymes (P<0.05), (2) a significant negative correlation of urease, phosphatase and sucrase activities with NH+4-N content, and (3) a significant positive correlation of protease activity with sediment NO-3-N content. The results of this study demonstrate that planting lotus in a fish cultivation pond decreases sediment nutrient levels and increases the activities of nutrient converting enzymes.