7份红萍种质资源生态化学计量特征比较及饲用价值评价

Ecological Stoichiometry Characteristics and Feeding Value Evaluation of Seven Azolla Germplasm Resources

【目的】比较不同红萍种质资源在广西桂林的生态化学计量特征,评价其饲用价值,为红萍的养分管理和生产利用提供科学依据。【方法】在露天土壤水培养条件下,检测细绿萍(Azolla filiculoides Lam)、卡州萍(A.caroliniana Willd)、覆瓦状萍[A.imbricate(Roxb.) Nakais]、羽叶萍(A.pinnata R. Brown)、杂交萍(Hybrid Azolla)、回交萍2(Backcrossed Azolla. MH2)和回交萍3(Backcrossed Azolla. MH3)等7份红萍种质资源的养分含量和营养指标,分析其碳(C)、氮(N)、磷(P)和钾(K)的生态化学计量特征,并通过隶属函数法综合评价其饲用价值。【结果】覆瓦状萍的鲜生物量和繁殖系数最高,分别为1.69 kg/m^2和0.77 kg/d/小区;细绿萍、卡州萍、覆瓦状萍、杂交萍、回交萍2和回交萍3的N、P和K三要素总分达一级有机肥标准,羽叶萍的N、P和K三要素总分达二级有机肥标准;7份红萍种质的N/P(3.80~5.46)均较低,说明N是红萍生长的限制因子;各种质的饲用价值排序为杂交萍>卡州萍>细绿萍>回交萍3>回交萍2>覆瓦状萍>羽叶萍。【结论】在广西桂林地区露天土壤水培养条件下,N是红萍生长的限制因子;7份红萍种质资源作为绿肥均具有较高的潜在应用价值,其中覆瓦状萍的鲜生物量和繁殖系数最高,生长适应性最强,杂交萍的饲用价值最高,该2份种质资源更适宜在桂北地区的稻—萍—鱼/鸭农业生态模式中推广应用。

【Objective】To provide scientific basis for guiding nutrient management and utilization of Azolla,the ecological stoichiometry characteristics of different Azolla germplasm resources in Guilin, Guangxi were compared,and their fertilizer and feeding values were evaluated.【Method】Under the condition of outdoor soil hydroponics,nutrient contents and indexes of seven species of Azolla germplasm resources,including A. filiculoides Lam,A. caroliniana Willd,A. imbricate(Roxb.) Nakais,A. pinnata R. Brown,Hybrid Azolla,Backcrossed Azolla. MH2 and Backcrossed Azolla. MH3 have been researched. The ecological stoichiometry characteristics of C,N,P and K were analyzed,and the feeding nutritional value was comprehensively evaluated by membership function method.【Result】The A. imbricate(Roxb.) Nakais had the highest fresh biomass(1.69 kg/m^2) and reproductive coefficient(0.77 kg/d/plot). The total score of N,P and K elements of A. filiculoides Lam,Azolla caroliniana Willd,A. imbricate(Roxb.) Nakais,Hybrid Azolla,Backcrossed Azolla. MH2 and Backcrossed Azolla. MH3 reached the first-class organic fertilizer standard,and A. pinnata R. Brown reached the second-class organic fertilizer standard. The N/P of seven Azolla species were low(3.80~5.46),which indicates that nitrogen maybe the limiting factor for the growth of Azolla. The comprehensive evaluation of feeding value of Hybrid Azolla,A. caroliniana Willd,A. filiculoides Lam,Backcrossed Azolla. MH3,Backcrossed Azolla. MH2,A. imbricate(Roxb.) Nakais and A. pinnata R. Brown follow a descending order.【Conclusion】Under the condition of outdoor soil hydroponics in Guilin,Guangxi,nitrogen is the limiting factor affecting the growth of Azolla,and the seven Azolla germplasm resources have high potential application value as green manure. Among them,the fresh biomass,propagation coefficients and growth adaptability of A. imbricate(Roxb.) Nakais was the best. However,the feeding value of Hybrid Azolla was the optimal. Therefore, A. imbricate(Roxb.) Nakais and Hybrid Azolla are more suitable to be applied in the rice-Azolla-fish/duck agricultural ecological model in northern Guangxi.