Mohammed, Abdul Razack , Rounds, Elliott W. , Tarpley, Lee .
Response of rice tillering to sub-ambient levels of ultraviolet-B radiation.
Low levels of ultraviolet-B (UV-B: 280-320 nm) radiation below the canopy in densely planted rice (Oryza sativa L.) fields have a negative impact on tiller initiation and development. Moreover, there is a varietal difference in the response to UV-B radiation in rice. The objective of this study was to examine the effects of UV-B radiation on rice physiology with special emphasis on tiller development of both the main and ratoon crops for three different rice cultivars: Cocodrie, Saber and CL-161. Rice plants were exposed to UV-B radiation of 0 (control), 8 (ambient), or 16 (twice ambient) kJ m-2 d-1 in Experiment I and 0, 4 (sub-ambient) or 8 kJ m-2 d-1 in Experiment II. Exposure was from 20 d after emergence to the early grain-filling stage (76 d after emergence), in a square-wave approach for 8 h from 0800 to 1600 h. The UV-B radiation intensity was checked daily with a UVX digital radiometer. Plant height, tiller number per plant, and chlorophyll content showed no significant (P>0.05) difference between cultivars at 8 and 16 kJ m-2 d-1. There was, however, a significant (P>0.05) difference between the control and ambient UV-B levels for tiller number per plant in Experiment I. Control plants were taller and had more chlorophyll content when compared to the UV-B treatments, but this difference was not significant. In the second experiment, there was no significant (P>0.05) difference between the control and UV-B treatments with respect to plant height and chlorophyll content for all three cultivars. There was, however, a significant (P>0.05) difference between the ambient and sub-ambient UV-B levels with respect to tiller number in Experiment II. Our results show that UV-B radiation plays an important role in tiller initiation and development. Partially supported by the Texas Rice Belt Warehouse and Texas Rice Research Foundation.
Log in to add this item to your schedule
1 - Texas Agricultural Experiment Station, TAMU Dept. Soil and Crop Sciences, 1509 Aggie Dr., Beaumont, Texas, 77713
Presentation Type: Oral Paper
Date: Monday, August 15th, 2005
Time: 11:00 AM