Effect of Simultaneous Water Deficit Stress and Meloidogyne incognita Infection on Cotton Yield and Fiber Quality

摘要

Both water deficit stress and Meloidogyne incognita infection can reduce cotton growth and yield, and drought can affect fiber quality, but the effect of nematodes on fiber quality is not well documented.To determine whether nematode parasitism affects fiber quality and whether the combined effects of nematode and drought stress on yield and quality are additive (independent effects),synergistic,orantagonistic,weconductedastudyfor7yrina fieldinfestedwith M.incognita.Asplit-plotdesignwasusedwith the main plot factor as one of three irrigation treatments (low nonirrigated, moderate irrigation, and high irrigation waterreplete) and the subplot factor as 0 or 56 l/ha 1,3-dichloropropene.We prevented water deficit stress in plots designated as water-replete by supplementing rainfall with irrigation.Plots receiving moderate irrigation received half the water applied to the water-replete treatment.The severity of root galling was greater in nonfumigated plots and in plots receiving the least irrigation, but the amount of irrigation did not influence the effect of fumigation on root galling (no irrigation 3 fumigation interaction).The weights of lintand seedharvestedwerereducedin nonfumigatedplotsandalsodecreasedasthelevelof irrigationdecreased,butfumigation didnotinfluencetheeffectofirrigation.Nematodesaffectedfiberqualitybyincreasingmicronairereadingsbuttypicallyhadlittleor no effect on percent lint, fiber length (measured by HVI), uniformity, strength, elongation, length (based on weight or number measured by AFIS), upper quartile length, or short fiber content (based on weight or number).Micronaire also was increased by water deficit stress, but the effects from nematodes and water stress were independent.We conclude that the detrimental effects caused to cotton yield and quality by nematode parasitism and water deficit stress are independent and therefore additive.