Studies on the mode of iron application and growth regulators on rice 213 STUDIES ON THE MODE OF IRON APPLICATION AND GROWTH REGULATORS ON THE PERFORMANCE OF DIRECT SEEDED UPLAND RICE ( ORYZA SATIVA L.) VARIETIES UNDER RAINFED CONDITION S.K. SARANGI, H.C. SHARMA, KALYAN SINGH, Y. SINGH, C.S. SINGH AND K.K. SINGH Department of Agronony, Institute of Agricultural Sciences, Banaras Hindus University, Varanasi - 221 005 ABSTRACT Field experiment was carried out to judge the mode of iron application and growth regulators on the performance of direct seeded upland rice varieties under rainfed condition at the Research Farm, Department of Agronomy, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, during rainy seasons of 2001 and 2002. Two varieties (ZHU-XI-26 and NDR-97) and three growth regulators (control, paclobutrazol and cycocel) were combined to give six main plot treatments whereas five subplot treatments were modes of iron application (control-M0), 25kg FeSO 4 ha -1 as basal (M1), 1.0% foliar spray (10kg FeSO 4 ha -1 ) and 1.5% (15kg FeSO 4 ha -1 ) at 25 and 35 days after sowing (DAS), respectively (M2), 15 kg FeSO 4 ha -1 based +1.0 10 h -1 foliar spray 15DAS (M1) and foliar spray of 0.1% Fe EDTA at 25 and 35 DAS (M4) were laid out in a split plot design with 3 replications. The available marked products of growth regulators paclobutrazol (cultar) and cycocel (lithocin) were applied @ 100ppm each at 20 and 40DAS through foliar spray. The variety ZHU-XI-26 performed better than NDR-97. Growth regulator paclobutrazol increased grain yield significantly over cycocel application. Among the mode of application, 15kg FeSO 4 ha -1 as based+ 1.0% (10 kg ha -1 ) foliar spray 35DAS though at par with foliar spray of 0.1% Fe EDTA at 25 and 35 DAS produced higher yield than other modes of application. Key words : FeSO 4 , FeEDTA, growth regulator, iron application, rice. Research efforts during the last decades have been instrumental in diagnosing and prioritizing various biological and technological constraints limiting productivity of upland rice. The two major problems confronting upland rice production are lack of proper nutrition and moisture stress. Under rainfed upland conditions rice crop often suffers from iron deficiency during the seedling stage due to aerobic conditions, which favours the oxidation of Fe ++ to Fe +++ (Brown, 1961). These ferric forms precipitate and get deposited on the root surface as ferric oxide and ferric hydroxides and prevent the entry of soluble ferrous iron into the root system. As a result, the plant suffers from iron deficiency and exhibits chlorosis in young leaves (Reddy and Prasad, 1986). Iron deficiency chlorosis under upland conditions does not necessarily indicatea deficiency of this nutrient in the soil, but it is indicative of the plant inability either to absorb it from the soil or utilize it efficiently (Brown et Ann. Agric. Res. New Series Vol. 27 (3) : 213-219 (2006) al., 1991), plant genotypes differ in their ability to take up Fe (Singh et al., 1992), so Fe efficient varieties should be selected for conditions where Fe deficiencies are likely to occur (Tisdale et al., 1997). To achieve the maximum yield potential, growth regulators have contributed a great deal to the progress of agricultural sciences. Growth retardants like paclobutrazol and cycocel may improve the physiological and morphological characteristics of rainfed upland rice by manipulating root characteristics and flow rate of photosynthates for grain development. These compounds when used in appropriate concentrations in rainfed upland rice varieties influence the plant architecture in a typical fashion (Dicks, 1980) by phenomenon characterized as (a) inhibition of shoot growth (plant height, internode elogation, leaf area) with unchanged number of internodes and leaves with intensified green leaf pigmentation and (b)