Potassium Fertilization Effects on Cotton Lint Yield, Yield Components, and Reniform Nematode Populations

originally found in Mississippi in 1980 and by 2002 was estimated to infest 32.4% of the cotton hectarage in Cotton (Gossypium hirsutum L.) lint yields have not changed apMississippi (Lawrence et al., 2002). Although genetics preciably during the last decade. Because more and higher infestations is still probably the predominant reason for the lack of of reniform nematodes (Rotylenchulus reniformis) have been identified in mid-southern USA fields, this nematode might be a mitigating yield improvements, these higher field infestations of factor in the cotton yield stagnation. The objectives were to determine reniform nematodes may also be a mitigating factor. how varying rates of K fertilization interacted with different cotton The emergence of reniform nematodes as an economgenotypes to influence dry matter partitioning, lint yield, fiber quality, ically challenging pathogen in cotton production has led and reniform nematode populations. Nine cotton genotypes were to the desire to incorporate cotton genotypes resistant grown in the field under two levels of K fertilization (0 and 112 kg to reniform nematodes into current production schemes. K ha 1) and two levels of aldicarb [2-methyl-2-(methylthio)propionalWhile reniform nematode resistance exists in some of dehyde 0-methylcarbamoyloxime] application (0 and 1.68 kg a.i. ha 1) the diploid Gossypium species, no commercial cotton from 1999 through 2001. Reniform nematode numbers and abovecultivars have yet been identified that possess reniform ground dry matter partitioning were determined at various times in resistance (Koenning et al., 2004). While screening efthe growing season. Lint yield, yield components, and fiber quality were determined at the end of the season. Cotton grown with K forts of cotton cultivars have yet to detect resistance to fertilization hosted a 12% larger post-harvest population of reniform reniform nematodes (Robinson et al., 1999), the number nematode than the unfertilized control plants. Plants grown without of commercial genotypes that could be screened at any K fertilization averaged a 10% greater specific leaf weight than the one time is constrained by the logistics of the experiK fertilized plants. Of the 9 genotypes grown, only PayMaster 1218BR ment. Some cotton germplasm lines have been identified increased lint yield (10%) in response to K fertilization. An interaction that support statistically less nematode reproduction between aldicarb application and K fertilization for lint yield during (Robinson et al., 2004). Most of these screening efforts the 2000 growing season indicated that both reniform nematode parautilized plants grown in pots inside greenhouses or sitism and insufficient K fertilization may impose limitations to lint growth chambers, with the resistance characterized by yield production. Large reinform nematode populations may be supthe ability of the nematodes to reproduce relative to pressing the yield response to K fertilization. Production practices that encourage robust plant growth may enhance proliferation of that of a standard susceptible host (Koenning et al., 2004). existing reniform nematode populations. Research quantifying how various aspects of plant growth and development are impacted by reniform nematode parasitism among a diverse group of cotton genotypes under field conditions is limited. Jones et al. (1959) reI recent years, lint yields in the midsouthern portion of the U.S. cotton (Gossypium hirustum L.) producported that fumigation to suppress reniform nematode populations in field plots produced cotton yield increases, tion belt have become stagnant with little or no improvement as newer varieties have been adopted (Meredith, earlier maturity, and larger bolls. Lint percentage was inconsistently increased as a result of suppressing reni2002). While this yield stagnation period has coincided with increased usage of transgenic cotton genotypes in form nematodes in their research. Following a period during the late 1980s and early the USA, recent research has indicated that at least some of the new transgenic cottons were not more sus1990s when late season K deficiency symptoms could occasionally be observed in cotton production fields across ceptible to moisture deficit stress, in terms of yield, than their conventional cotton recurrent parents (Pettigrew, the U.S. production belt, considerable research has been conducted on cotton K fertility during the past 15 yr. 2004). During this similar time frame, reniform nematodes (Rotylenchulus reniformis) have also become more From this research, we have learned that because of decreased leaf photosynthesis (Bednarz and Oosterhuis, entrenched as a serious economic pathogen in the Mississippi Delta (Koenning et al., 2004). This nematode was 1999), reduced leaf area index (Pettigrew and Meredith, 1997), and lower levels of solar radiation interception (Gwathmey and Howard, 1998), K deficiency can lead USDA-ARS, Crop Genetics and Production Research Unit, P.O. to reduced cotton lint yields and poorer fiber quality Box 345, Stoneville, MS 38776. Trade names are necessary to report (Bennett et al., 1965; Cassman et al., 1990; Minton and factually on available data; however, the USDA neither guarantees nor warrants the standard of the product or service, and the use of Ebelhar, 1991; Pettigrew et al., 1996). One of the other the name by USDA implies no approval of the product or service to interesting findings from this period of research is the the exclusion of others that may also be suitable. Received 29 Dec. fact that increased levels of root galling from the south2004. *Corresponding author ([email protected]). ern root-knot nematode (Meloidogyne incognita) were Published in Agron. J. 97:1245–1251 (2005). found on cotton plants grown under K-deficient condiCotton doi:10.2134/agronj2004.0321 © American Society of Agronomy Abbreviations: DAP, days after planting; LAI, leaf area index; SLW specific leaf weight. 677 S. Segoe Rd., Madison, WI 53711 USA 1245 Published online July 13, 2005