Agronomic and physiological responses of resistant and susceptible cotton genotypes to reniform nematode severity and soil nitrogen
AdvisorChastain, Daryl R.
Reddy, K. Raja
CommitteeSnider, John L.
Krutz, L. Jason
Stetina, Salliana R.
Embargo TypeVisible to MSU only for 2 Years
Embargo Lift Date05/16/2022
Rotylenchulus reniformis (RN) nematode infection has been identified as a major biotic factor limiting cotton yield (~8%) in Mississippi. Cotton researchers are striving to develop resistance to RN and develop management practices to mitigate the problem. Reniform nematode and soil nitrogen (N) directly affect cotton growth and physiology, however, responses to RN and N may vary across a wide genetic background. The overall objective of this research was to determine the role that host plant resistance to reniform nematode and soil nitrogen plays in cotton growth, physiology, and yield and controlling RN populations. In experiment 1, the effect of RN on resistant (Gossypium barbadense introgressions; 08SS110-NE06.OP and 08SS100) along with a susceptible genetic standard (Deltapine 16) and a commercially, susceptible cultivar (PHY 490 W3FE) was studied based on growth, development, and yield characteristics under field conditions. In experiment 2, the effect of N application rates, ranging from 0-150%, with 100% being recommended rate, on early season morphological and physiological traits of the resistant and susceptible genotypes were studied in the presence and absence of RN under greenhouse conditions. In the field project, agronomic traits varied among genotypes at a given sampling time but growth rates, described by three-parameter sigmoidal function (r2 = 0.95 to 0.99), were not different among genotypes. Further, genotypes exhibited higher agronomic and physiological traits, including plant height, main stem nodes, leaf area, net photosynthetic rates, and hand-picked lint yields in 2018 than 2017. In the greenhouse study, 08SS110-NE06.OP performed physiologically better across RN environments than other genotypes, but growth rates with respect to soil N treatments, described by linear or quadratic function (r2 = 0.72 to 0.99), were not different among genotypes. No interactions between soil N treatments and RN based on physiological and growth traits were observed at the time of harvesting. In both projects, resistant genotypes suppressed reniform nematode population at the time of harvesting. RN resistant lines have no biological significant effect on plant growth, development, or yield but do suppress RN populations.