|Meredith Jr, William|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2005
Publication Date: 7/13/2005
Citation: Pettigrew, W.T., Meredith Jr, W.R., Young, L.D. 2005. Potassium fertilization effects on cotton lint yield, yield components, and reniform nematode populations. Agronomy Journal. 97:1245-1251. Interpretive Summary: In recent years, lint yields in the midsouthern portion of the U.S. cotton production belt have become stagnant with little or no improvement as newer varieties have been adopted. This time period also saw widespread adoption of transgenic cotton varieties in production systems and the entrenchment of reniform nematodes (microscopic worms) as a serious economic pathogen in the Mississippi Delta . In addition, no commercially available cotton varieties are known to suppress reproduction of the reniform nematode. Prior research involving potassium fertility in cotton demonstrated that potassium deficient plants were more susceptible to predation from the southern root-knot nematode. It is not know how potassium effects reniform nematode populations. Therefore, the purpose of this three year study was to determine how multiple cotton varieties (transgenic and conventional) responded to two levels of potassium fertilization (fertilized and unfertilized) in terms of growth and development, lint yield production, and the population levels of reniform nematodes detected. Similar levels of reniform nematode infestation were observed with all of the varieties grown. Cotton grown with potassium fertilization hosted a 12 % larger population of reniform nematodes than the unfertilized plants. Presumably, the potassium fertilized plants were more robust with larger root systems for the reniform nematodes to feed and reproduce upon. Because of an apparent lack of useful resistance in commercially available varieties, producers should be aware that production practices that support robust plant growth may also encourage the proliferation of reniform nematodes to yield limiting population levels in certain soil types, if they are already present in the field.
Technical Abstract: Cotton (Gossypium hirsutum L.) lint yields have not changed appreciably during the last decade. Because more and higher infestations of reniform nematodes (Rotylenchulus reniformis) have been identified in mid-southern USA fields, this nematode might be a mitigating factor in the cotton yield stagnation. The objectives were to determine how varying rates of K fertilization and of aldicarb application interacted with different cotton genotypes to influence dry matter partitioning, lint yield, fiber quality, and reniform nematode populations. Nine cotton genotypes were grown in the field under two levels of K fertilization (0 kg K ha-1 and 112 kg K ha-1) and two levels of aldicarb application (0 kg a.i. ha-1 and 1.68 kg a.i. ha-1) from 1999 through 2001. Reniform nematode counts and above ground dry matter partitioning were determined at various times in the growing season. Lint yield, yield components, and fiber quality were determined at the end of season. Cotton grown with K fertilization hosted a 12 % larger post-harvest population of reniform nematode than the unfertilized control plants. Plants grown without K fertilization averaged a 10 % greater specific leaf weight than the K fertilized plants. Of the 9 genotypes grown, only PayMaster 1218BR increased lint yield (10 %) in response to K fertilization. An interaction between aldicarb application and K fertilization for lint yield during the 2000 growing season indicate that both reniform nematode predation and insufficient K fertilization may impose limitations to lint yield production. Larger reinform nematode population may be suppressing the yield response to K fertilization. Production practices that encourage robust plant growth may enhance proliferation of existing reniform nematode populations.