Field Performance and Heritability of Thrips Resistance for Cotton Variety Development

In the absence of synthetic pesticide applications, thrips (Thysanoptera: Thripidae) management can be more problematic in organic production systems than conventional cotton systems.  Additionally, nearly all organic cotton acreage on the Texas High Plains (THP) is planted with one or two conventional cultivars and seed-saving is near-ubiquitous, as these cultivars are no longer commercially available.  Therefore, development of new thrips-tolerant, non-transgenic cultivars has the potential to greatly improve the availability and diversity of viable cultivars and overall production of organic cotton on the THP.  Fifteen advanced breeding lines (developed by the Texas A&M Cotton Improvement Program at Lubbock), 4 cultivars, and 1 newly-released germplasm line (developed by the Texas A&M Cotton Improvement Program at College Station) were planted at 2 field locations in 2013.  Each genotype was evaluated for thrips resistance potential and overall field performance under organic management.  Thrips resistance was assessed using visual injury ratings at both study sites, whereas weekly thrips monitoring from each genotype occurred at one of the field sites.  Yield and fiber quality data were collected to evaluate overall field performance of each genotype.  In addition, two broad-sense heritability trials were conducted to evaluate the inheritance of the thrips resistance trait and potential utility in variety development.  Two separate families were evaluated, each originating from different interspecific Gossypium hirsutum L. and Gossypium barbadense L. crosses.  One family was evaluated at the field level, while the other was evaluated in a greenhouse test.  Results are presented herein.