Effect of Two Types of Controlled-Release Urea on Physiological Characteristics, Yield and Quality of Peanut.

ABSTRACT  Coated fertilizers have been widely used in wheat and corn, but the effects of coated fertilizers on peanut growth have rarely been reported. In this study field experiments were conducted for two years to evaluate the effects of controlled-release urea coated by sulphur(SCU) or resin (RCU) on physiological characteristics, yield and quality of peanut (Arachis hypogea) on a loam soil.  The application rates were 0, 120, 150, and 180 kg N ha-1 for SCU, RCU or urea (control). The SCU or RCU was applied when peanut seeds were sown, whereas urea was split into two applications: 60% applied at seed sowing (SS) and 40% at the flowering stage (FS). Results showed that SCU and RCU significantly increased chlorophyll content at the mid and late growth stages, and improve photosynthetic rate by 11.50% and 11.79%, respectively at the mid-growth stage, and increased photochemical maximum efficiency of PSⅡ (Fv/Fm), the actual photochemical efficiency (ΦPSⅡ) and photochemical quenching coefficient(qP) compared to common urea treatment. SOD, POD and CAT contents generally increased but MDA decreased with the application rate regardless of fertilizer type. The SCU and RCU treatments at 150 kg N ha-1, though with one-sixth less N, resulted in 20.38% and 34.58% higher pod yield, respectively, as compared to urea (180 kg N ha-1) in two years.