Status of iron in Kula Ronghai area and response of Khao Dok Mali 105 rice to iron foliar fertilizer

Abstract

Status of soil iron (Fe) in Kula Ronghai area and effect of Fe fertilizers on Khao Dok Mali 105 (KDML 105) rice planted in Roi Et soil series (Re) in Surin province and salt affected soils, Roi Et soil series, saline variant (Re-sa) and Phimai soil series (Pm) in Nakhon Ratchasima province, were investigated. Foliar application was performed at the rates: 0, 0.25, 0.5 and 1 kg/rai of Fe at tillering or booting stages. Results showed that most soil Fe was in a total form as a component of soil minerals. The content of extractable form in the soils was the highest when extracted with DTPA-AB but clearly lower proportion than the total Fe. Water soluble Fe, the readily available form, was found only in very small amounts. Foliar application of Fe statistically increased straw weight and grain yield of rice, especially when applied at the rate of 0.25 kg/rai at tillering stage, significantly giving the highest straw weight of 541 kg/rai in Re soil series, and grain weight of 248 and 144 kg/rai in Re soil series and Re-sa, respectively. Foliar application of Fe at the rate of 1 kg/rai at the same growth stage also significantly gave the highest grain weight of 262 kg/rai in Pm soil series. In addition, Fe foliar application at tillering stage significantly promoted greater straw weight and grain yield of rice than did at booting stage. Foliar application of Fe significantly increased the concentration and uptake of major plant nutrients. Grain yield and straw weight of rice had negative correlation with Fe concentration in rice husk and bran (r=-0.43** and -0.29**).  Filled grain percentage of rice correlated with Fe (r= 0.21*), but negatively correlated with N (r=-0.72**) concentrations in rice grain.