Iron, Silica, and Aluminum Stresses and Varietal Resistance in Rice: Effects on Whitebacked Planthopper
- M. Salim and
- R. C. Saxena
Certain physicochemical stresses affect the susceptibility of plants to insects. The objective of this study was to determine the effects of different levels of Fe, Si, and Al on the establishment of Sogatella furcifera (Horváth) on resistant IR2035-117-3 (IR2035) and susceptible Taichung Native 1 (TN1) rice (Oryza saliva L.) cultivars under glasshouse conditions in natural daylight of 12 h, 29/21 °C (day/night), and minimum 70% relative humidity. Insect population increased on rice plants grown in culture solution containing low (0.02 mg L−1) or high (40 mg L−1) Fe than on plants grown in standard culture solution (Fe at 2 mg L−1). Increased Si (400 mg L−1) reduced intake and assimilation of food, growth, adult longevity, fecundity, and population increase by S. furcifera on susceptible TN1 plants. Addition of Al to culture solution at 90 mg L−1 adversely affected insect biology. Regardless of the mineral stress, the difference between the resistance of IR2035 and susceptibility of TN1 cultivars remained distinct. Plants affected with low or high Fe stress had apparently less allelochemicals than did control (unstressed) plants. Mortality of S. furcifera first instars was greater on TN1 plants painted with steam-distillate extract of Fe-stressed or control IR2035 plants than on TN1 plants painted with TN1 extract or acetone. Iron and Al stresses significantly decreased the growth and biomass of rice plants. Resistance of rice plants to S. furcifera can be improved by application of Fe at optimum (2 mg L−1) and Si at high (400 mg L−1) rates.
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