The relationship between commercial cotton cultivars with varying Meloidogyne incognita resistance genes and yield

Abstract

Small plot cotton cultivar trials (12 trials) were conducted from 2016 to 2019 in fields infested with Meloidogyne incognita. Entries in these trials included commercial cultivars with partial and high resistance to M. incognita, as well as cultivars with no known resistance. Different resistant groups were created based on different cotton seed companies and their descriptions of the M. incognita resistant cultivars. Groups were none (susceptible); partial resistance found in Stoneville or Fibermax cultivars (PR-FM/ST); partial resistance found in PhytoGen cultivars (PR-PHY); resistance (unknown gene(s)) in Deltapine cultivars (NR-DP); and highly resistant cultivars homozygous for RK1 and RK2 resistant genes in PhytoGen cultivars (HR-PHY). The highest lint yields using a mixed model analysis were found in the PR-FM/ST (1,396 kg lint/ha), HR-PHY (1,327 kg lint/ha), and PR-PHY (1,314 kg lint/ha) groups. Yield for NR-DP (1,234 kg lint/ ha) was not different (p > 0.05) than yield for susceptible cultivars (1,243 kg lint/ha). If the older resistant cultivars from Deltapine and PhytoGen (those with only Roundup Ready® herbicide technology) were removed from the analysis, then HR-PHY yields increased by 133 kg of lint/ha to 1,460 kg lint/ha and NR-DP yields remained approximately unchanged (1,227 kg lint/ha). Newer HR-PHY had much improved yield over the first HR-PHY cultivars. Newer HR-PHY averaged 17% higher yield than the susceptible group. LOG 10 (M. incognita eggs/500 cm 3 soil + 1) were highest for the susceptible cultivars (3.2), followed by PR-FM/ST (2.6), NR-DP (2.4), PR-PHY (2.1), and lowest with HR-PHY (1.4). The newer HR-PHY cultivars (those with ENLIST ® herbicide technology) combine excellent yields (17% higher than susceptible cultivars) with high (96%) suppression of M. incognita.

Evaluation of Meloidogyne incognita and Rotylenchulus reniformis nematode-resistant cotton cultivars with supplemental Corteva Agriscience nematicides

“…Each year of the experiments, new seeds of each cultivar were assessed and, in both years, the PHY 360 (R) and PHY 332 (R) supported less than 35% and first 20%, respectively, of the populations that developed on the susceptible PHY 340 cultivar. Considerable progress has been made since the initial introduction of the first commercial cotton cultivar LA887, which was registered with partial resistance to M. incognita ( Jones et al, 1991 ; Wheeler et al, 2020 ). Breeding efforts have been working toward the commercial release of resistant cultivars including the initial breeding with the G. hirsutum species by Starr et al, (2007) and Weaver et al, (2007) and with G. longicalyx by Robinson et al (2007) and Bell et al (2014).…”

“…We observed the reduction in nematode populations on these newly released cotton cultivars. These new cotton cultivars have improved from the first PHY 417 WR cotton cultivar, which had high resistance to M. incognita but poor yield potential and thus had limited commercial adaptation (Fuchs et al, 2015; Wheeler et al, 2020 ).…”

“…Currently, there are at least 10 cotton cultivars with one or two genes for resistance to M. incognita available through Corteva Agriscience, Bayer, and BASF ( Kichler, 2021 ). Cotton cultivars that have some form of resistance to M. incognita are listed in Table 1 ( Weaver, 2015 ; Corteva Agriscience, 2018; Wheeler et al, 2020 ).…”

“…The two PhytoGen R. reniformis -resistant cultivars contain three genes for resistance, which include two genes for resistance to M. incognita and an additional gene that adds the R. reniformis resistance. The cotton cultivars with R. reniformis resistance are listed in Table 1 ( Weaver, 2015 ; Corteva Agriscience, 2020; Wheeler et al, 2020 ). High-yielding cotton cultivars often are planted on large percentages of the acres without rotations.…”

Cotton host resistance as a tool for managing Rotylenchulus reniformis in Louisiana

“…Crop rotation to a non-host, such as corn and grain sorghum, can also be used for management of reniform nematode populations in a field ( Davis et al 2003 ); however, such rotations may not be as economically profitable as cropping with a susceptible crop, such as cotton and soybean. Cotton host resistance has been used to reduce damage associated with other nematode species, including southern root-knot nematode ( Meloidogyne incognita ) ( Ogallo et al 1997 ; Koenning et al 2001 ; Wheeler et al 2014 ). Deploying effective cotton host resistance to reniform nematode may provide an additional management tool for reniform nematode in cotton production.…”