McSorley R, Dickson D W
J Nematol. 1989 Oct;21(4):490-9.
The relationships between densities of all members of a plant-parasitic nematode community and yield of 'Davis' soybean and between final and preplant population levels were examined in small plots on sandy soils in north-central Florida. Plant-parasitic nematodes present in the community included Belonolaimus longicaudatus, Criconemella sphaerocephala, Meloidogyne incognita, Paratrichodorus minor, Pratylenchus brachyurus, and Xiphinema sp. Plant growth, including stand count, soybean yield (kg/ha), and size of young plants, was occasionally inversely correlated (P </= 0.05) with densities of B. longicaudatus or P. brachyurus, but not with densities of other species or with a range of soil variables. The nature of this relationship varied with season, with more severe stand losses noted during 1987 than in 1988. Final population densities (Pf) of most nematode species showed significant (P </= 0.05) linear relationships to densities measured at planting or earlier (Pi). These relationships were stronger (higher r(2)) with the ectoparasite B. longicaudatus than with the endoparasites M. incognita and P. brachyurus. Criconemella sphaerocephala declined under soybean cultivation, reaching levels near zero after two seasons. A quadratic model showed an improvement (P </= 0.05) over the linear model in describing the relationship between Pf and Pi measured at planting for B. longicaudatus, and gave a better indication of the leveling off of Pf at high values of Pi.
在佛罗里达州中北部的沙质土壤小地块上，研究了植物寄生线虫群落所有成员的密度与‘戴维斯’大豆产量之间的关系，以及最终种群水平与种植前种群水平之间的关系。群落中存在的植物寄生线虫包括长尾纽带线虫、球形环线虫、南方根结线虫、微小拟毛刺线虫、短体线虫和剑线虫属。植物生长情况，包括植株数量、大豆产量（千克/公顷）和幼苗大小，偶尔与长尾纽带线虫或短体线虫的密度呈负相关（P≤0.05），但与其他物种的密度或一系列土壤变量无关。这种关系的性质随季节变化，1987年观察到的植株损失比1988年更严重。大多数线虫物种的最终种群密度（Pf）与种植时或更早测量的密度（Pi）呈显著（P≤0.05）线性关系。外寄生的长尾纽带线虫的这些关系比内寄生的南方根结线虫和短体线虫更强（r²更高）。球形环线虫在大豆种植下数量减少，两个季节后降至接近零的水平。对于长尾纽带线虫，二次模型在描述种植时测量的Pf与Pi之间的关系方面比线性模型有所改进（P≤0.05），并且能更好地表明在Pi值较高时Pf趋于平稳的情况。
