Plant‐Parasitic Nematode Effects on Water Use and Nutrient Uptake of a Small‐ and a Large‐rooted Tall Fescue Genotype1

Abstract

AbstractPlant‐parasitic nematodes often adversely affect tall fescue (Festuca arundinacea Schreb.) on sandy soils in the Southeast. Stand and yield reduction and damage to root systems by plant‐parasitic nematodes have been reported, but little is known about the effect of these nematodes on plant functions such as water use and nutrient uptake.A controlled‐environment room experiment was conducted to determine the effect of plant‐parasitic nematodes on water use and nutrient uptake of two tall fescue genotypes with differing root systems, and to determine the feasibility of developing plants with root characteristics that would minimize the detrimental effects of nematodes. One of the genotypes (AF‐81) had many small‐diameter primary roots with a median diameter of 1.0 mm. The other genotype (AF‐7) had fewer and larger roots with a median diameter of 2.2 mm. The two genotypes were grown in Cahaba loamy sand topsoil (Typic Hapludult, fine‐loamy, siliceous, thermic) with and without a mixed population of plant‐parasitic nematodes. Measurements were made of root development, water use, forage yield, and Ca, Mg, and K content of the forage.The small‐rooted genotype produced 30% more forage and was more efficient in water use than the large‐rooted genotype. Nematodes suppressed forage yield of the small‐ and large‐rooted genotypes by 9 and 50%, respectively, but had no effect on water use efficiency. Nematodes severely retarded root growth of the large‐rooted genotype, but had only a moderate effect on root growth of the small‐rooted genotype. The large‐rooted genotype supported twice the population of lance nematodes (Hoplolaimus galeatus [Cobb] Sher.) as did the small‐rooted genotype. Nematodes reduced forage Mg content of both genotypes to levels that could cause tetany in ruminants. Root size may be important in determining the effect of plant‐parasitic nematodes on plant performance and should be considered by plant breeders in developing nematode‐tolerant cultivars.