Effect of iron and manganese on Khao Dok Mali 105 rice grown in different paddy soils

Abstract

Khao Dok Mali 105 rice was planted in greenhouse to study its response to different rates of iron (0, 2, 4, 8 and 16 mg Fe/kg) and manganese (0, 0.5, 1.0,  2.0 and 4.0 mg Mn/kg) in Tha Tum, Roi Et and Ubon soils series. Results showed that plant height in these three soils decreased significantly with increasing rate of Fe while number of panicle in Roi Et soil series (11.0-11.3 panicle/pot) statistically increased with increasing rate of Fe except the rate 4 mg Fe/kg.  At this rate of 4 mg Fe/kg also resulted in significantly increased grain weight in Ubon soil series (17.2 g/pot) whereas the other rates gave no statistical difference to that of the control (6.93-8.37 g/pot) with the rate of 8 mg Fe/kg giving the lowest amount of 5.17 g/pot.  Manganese had no impact on rice yield components but induced similar plant height to the control in Ubon and Roi Et soil series with the except of 2 mg Mn/kg that gave the highest values of 162 and 165 cm, respectively.  Iron and Mn statistically improved nutritional fact of rice grain of which the addition of 2 mg Fe/kg induced the highest Fe and Zn in brown rice grain while the use of 4 mg Mg/kg increased only Zn concentration in the grain in Roi Et soil series. The application of 0.5 and 1 mg Mn/kg significantly increased the uptake of primary plant nutrients and Fe application decreased P and K uptake in Tha Tum and Ubon soil series. Rates of Fe that induced an increase in N uptake varied among soils, ranging between 4-16 mg/kg.  Iron concentration in plant tissue had no correlation with rice yield components but plant height correlated with Mn concentration in rice stover (r = 0.73*) and grain (r = 0.88*) as well as number of panicle that correlated with Mn concentration in rice stover (r = 0.73*).