Submitted to: Plant Pathology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/14/2006
Publication Date: 3/5/2007
Citation: Koti, S., Reddy, K.R., Lawrence, G.W., Reddy, V., Kakani, V.G., Zhao, D., Gao, W. 2007. Effect of enhanced uv-b radiation on reniform nematode (rotylenchus reniformis linford and oliveira) populations in cotton (gossypium hirsutum l.). Plant Pathology Journal. 6(1):51-59. Interpretive Summary: High density radiation (UV-B) reaching the earth's surface has increased by 6-14% since 1980 and is projected to rise further in the near future. Over the past two decades, several studies were conducted to evaluate the effects of high density radiation on growth and development of crop plants. However, few studies have addressed UV-B induced changes in plant chemistry and their influence on pests such as insects, snails, and nematodes. To quantify increased UV-B radiation effects on nematode populations, cotton plants were exposed to several levels of radiation. Plant growth, development, drymatter accumulation, pigments, and phenolics, along with the number of eggs and nematode numbers in the root zone, were recorded. We observed increased levels of leaf and root phenolic concentration with increased levels of UV-B radiation and decreased number of eggs and nematodes in the root zone. The results of this study can be used to screen cultivars for nematode tolerance.
Technical Abstract: Ultraviolet-B (UV-B) radiation reaching the Earth's surface has increased by 6-14% since 1980s and climate models project that UV-B will continue to rise in the near future. Many studies have evaluated the effects of increased UV-B radiation on plant growth and development, but its effect on plant biota is less known. To understand the increased UV-B radiation effects on reniform nematode (Rotylenchus reniformis Linford and Oliveira) populations, cotton (Gossypium hirsutum L.) plants were exposed to three levels of UV-B radiation [0 (control), 6 and 12 kJ m-2 d-1] in a glasshouse from emergence. At each UV-B treatment, four populations [0 (N0), 2500 (N2500), 5000 (N5000) and 7500 (N7500)] of reniform nematodes were incorporated into the sterilized rooting medium. Plant growth, development, photosynthetic parameters, pigments, phenolics and the number of eggs and nematode numbers in the rooting medium were recorded at the end of the experiment, 40 DAS. Even though, UV-B radiation did not significantly affect growth and development, it did significantly increase leaf and root phenolic concentrations. UV-B treatments significantly decreased both the egg and nematode numbers in all the nematode population treatments. Significant negative correlation was found between root phenolic concentrations and egg (r2 = 0.88) and nematode (r2 = 0.86) numbers. Similarly, leaf phenolics also showed significant negative trend with egg (r2 = 0.53) and nematode numbers (r2 = 0.47). Therefore, current and projected UV-B radiation levels may have an important regulatory influence on nematode populations.