The influence of verticillium wilt epidemics on cotton yield in southern Spain

Abstract

Experiments were conducted in the Guadalquivir Valley of Andalucía, southern Spain, in 1986 and 1987, using field plots naturally infested with different inoculum densities of the defoliating and nondefoliating pathotypes of Verticillium dahliae to determine the influence of verticillium wilt epidemics on yield of cotton cultivar Coker 310. The total number of bolls, the number of open bolls, and seed cotton yield were related to the growth stage of plants at first appearance of foliar symptoms, and to inoculum density and virulence of the V. dahliae pathotype prevailing in the soil. For the three yield components, the greatest reduction was observed in plants showing symptoms before opening of first flowers (about 650 degree-days after sowing). Yield increased with delay in the development of foliar symptoms during the crop season, and the effect of the wilt epidemics on yield was small or nil for plants that developed symptoms after opening of the first bolls (1400-1500 degree-days after sowing). A multiple regression equation was derived that related yield reduction to the physiological time accumulated from the time of sowing until the appearance of foliar symptoms and to the rate of disease intensity increase over physiological time. This multiple point model explained about 70% of the variation in cotton yield loss due to verticillium wilt.

Quantitative Trait Locus Mapping for Verticillium wilt Resistance in an Upland Cotton Recombinant Inbred Line Using SNP-Based High Density Genetic Map

“…These result variations in field investigations might be explained by the fact that in the natural field conditions, the cotton plants were subjected to the pressure of a mixture of VW strains. The quantity of soil fungi, virulence of the strains, and the developmental and environmental factors (Bejarano-Alcázar et al, 1997) might contribute to these result variations. Similar results were reported in a previous study, in which a parent reckoned susceptible during field investigations turned to be resistant in the greenhouse after root wounding for the pathogen inoculation (Fang et al, 2013a).…”

“…Plenty of genetic maps have been constructed using both interspecific (Bejarano-Alcázar et al, 1997; Mert et al, 2005; Zhang et al, 2015) and intraspecific (Jiang et al, 2009; Fang et al, 2013b; Ning et al, 2013; Zhang et al, 2014b) populations. However, most of the maps used for intraspecific cross studies have very low genome coverage (< 50%) and do not allow a genome-wide detection of QTLs with high resolution.…”

“…The use of a genetic map with higher map resolution and better genome coverage will still be valuable for QTL mapping and might provide more useful information to better understand VW resistance mechanism in upland cotton. On the other hand, plants responses to VW infection are sensitive to other factors, such as, the virulence of the strains, the level of inoculation, and the developmental and environmental factors (Bejarano-Alcázar et al, 1997). Therefore, the evaluation of VW resistance at different stages of growth (seedlings, flowering, and mature stage) and different environments (controlled conditions in greenhouse and naturally infected conditions in open field) appears to provide more promising information for VW resistant breeding practice in cotton.…”

Seed transmission of verticillium wilt of cotton

“…However, V. dahliae was detected in several countries on three continents (Bejarano-Alcázar et al 1997;Elena 1999;Katan 2000;Korolev et al 2008;Zhengjun et al 1998) during a 15-year period, and the disease often appeared in previously uninfested fields. For this reason, seed transmission of V. dahliae is being reexamined as a potential means of disease spread.…”

Scientific opinion on the pest categorisation of Verticillium dahliae Kleb

“…total number of bolls, number of open bolls and seed yield, were related to the growth stage of plants at first appearance of foliar symptoms, to inoculum density and the virulence of V. dahliae pathotype. The greatest reduction in yield was observed in plants showing symptoms before opening of first flowers, whereas small or nil reduction in yield was recorded for plants that developed symptoms after opening of the first bolls (Bejarano-Alcázar et al, 1997).…”