稻蟹共作系统对稻田水体丝状藻类的影响

Effect of rice-crab culture system on Spirogyra in paddy field

摘要:

在稻蟹共作稻田,采集放养不同密度幼蟹(60 ind/m²,低密度,T1;90 ind/m²,中密度,T2;120 ind/m²,高密度,T3)的稻蟹共作稻田和常规稻田(不放蟹,CK)的丝状藻类,测其干重量,研究稻蟹共作对稻田丝状藻类的影响.试验结果表明:在整个试验阶段,养蟹田丝状藻类的生物量显著低于常规稻田(P<0.05),说明幼蟹对稻田丝状藻类的生物量有明显的控制作用.6月17日,CK与T1的丝状藻类干重明显高于另两个处理(P<0.05),而T3明显低于其他处理(P<0.01);7月17日各处理丝状藻类的生物量均达到试验阶段的最大值,并且各处理间差异显著(T3 < T2 < T1 < CK, P<0.05; T3、T2 < T1 < CK, P<0.01);8月15日,各处理间有显著差异(T3 < CK,T2 < CK,T1 < CK,P<0.01;T2 < T1,P<0.05).根据本实验结果,稻蟹共作稻田大眼幼体的适宜放养密度为90 ind/m²,研究结果可为稻田生物防治丝状藻类提供理论指导,促进稻蟹共作技术的发展和推广.

Abstract:

Rice-crab culture system is a new ecological complex that combines rice culture with that of Eriocheir sinensis. The growth of Spirogyra will seriously affect the growth of rice and rice yield. To determine the effects of rice-crab culture systems on Spirogyra in paddy fields, periodic sampling was conducted in rice-crab culture systems with different megalopa densities (60 ind/m², T₁; 90 ind/m², T₂; 90 ind/m², T₃) and in conventional paddy field (CK) at five key dates (June 17th, June 28th, July 17th, July 30th and August 15th). The results show that the average dry weight of Spirogyra of the rice-crab culture fields and the conventional paddy fields were significantly different in the whole experiment period, and this shows the difference crab stocking density had obvious control action on the biomass of Spirogyra in the paddy fields. A certain amount of Spirogyra appeared on June 17, especially the average dry weight of Spirogyra of conventional paddy field (CK) and rice-crab culture field with low density of megalopa (T₁) were obviously higher than that of the other two treatments (P<0.05), and the average dry weight of Spirogyra of rice-crab culture field with high density of megalopa (T₃) was significantly lower than other treatments (P<0.01); On July 17th, the CK maximum biomass of Spirogyra, an average of dry weight 46.91±5.35 g, and area covered in 65%-75%, and other treatments also reached a maximum of the whole experiment period, and significant difference of different treatments(T₃ < T₂ < T₁ < CK, P<0.05; T₃ 1 < CK, T₂ < T₁ < CK,P<0.01); Sampling results on August 15, that there was no moss in rice-crab culture field with high density of megalopa (T₃), the T₂ lowest biomass of Spirogyra, the highest amount of in the CK, there were significant differences in different treatments (T₃ < CK, T₂ < CK, T₁ < CK, P<0.01; T₂ < T₁, P<0.05).The study provided additional theoretical guidance about biological control of Spirogyra and sustainable development of rice-crab culture systems. It provided another means of promoting the development of rice-crab culture technology.