Effect of Phosphorus on Nutrient Uptake of Japonica and Indica Rice

J Agric Rural Dev 6(1&2), 7-12, June 2008 Available online at http://www.banglajol.info/index.php/jard ISSN 1810-1860 JARD Journal of Agriculture & Rural Development Effect of Phosphorus on Nutrient Uptake of Japonica and Indica Rice M. A. ISLAM1*, M. R. ISLAM2 & A. B. S. SARKER3 1 Adaptive Research Division, Bangladesh Rice Research Institute, Regional Station-Sonagazi, Feni, Bangladesh 2 Adaptive Research Division, Bangladesh Rice Research Institute, Gazipur, Bangladesh 3 Agronomy Division, Bangladesh Rice Research Institute, Gazipur, Bangladesh ABSTRACT An experiment was conducted at the screen house of Tsukuba International Centre (TBIC), Japan to clarify the effect of phosphorus on nutrient absorption characteristics of a japonica (Nipponbare) and an indica (IR-28) rice variety. The experiment was conducted under submerged condition in subsoil of an Andisol, which had a high capacity of phosphate fixation. Levels of phosphorus were 100, 200, -1 500 and 800 kg P2O5 ha . The P content in rice plant at different growth stages increased progressively with an increase of P levels for both the varieties. With respect to P content, varietal differences were minimal. But in the case of N and K content, IR-28 showed higher ability than Nipponbare. At maximum tillering stage, both the varieties showed negative co-relation between P and N uptake but at harvest stage, strong positive co-relation between P and N uptake was found for both the varieties. Both the varieties showed positive co-relation between N and K uptake at all the stages. Key words: Andisol, IR-28, nipponbare, phosphorus, uptake. INTRODUCTION Rice is the staple food for the 140 million people of Bangladesh, and is grown here on around 10 million hectares. Most of the rice yield comes from high yielding variety (HYV) rice. Because of continuous growing of HYV rice and injudicious fertilizer management, many soils are getting exhausted. This is resulting in problems of P, K, and S deficiency in soils along with inherited N deficiency (Ali et al., 1997; Saleque et al., 1998a; Saleque et al., 1998b). Moreover, mineral fertilizers in this region are costly compared to the prices of rice. Thus, rice varieties with higher nutrient use efficiency (i.e. yield per unit nutrient absorbed) would be highly desirable. Compared with nitrogen (N) nutrition, phosphorus (P) nutrition of rice plants has received little attention, because under favorable soil conditions the response of rice to P fertilizer is far less marked than that to N. Phosphorus deficiency is likely to develop in many soils under intensive rice cultivation, and the use of improved varieties in rice production will increase the problem (IRRI, 1993). Rice varieties are known to differ in their ability to grow under low-P conditions (Neue, 1991). The more P efficient varieties may have internal and/ or external mechanisms that allow greater soil P extraction and grain yield. An understanding of the internal and external P efficiencies of modem varieties (MV) rice is very important in selection of varieties adaptable to P deficient conditions. * Corresponding author: Principal Scientific Officer, BRRI, RS–Sonagazi, Feni, Cell: 01715414017, E-mail: © 2008 School of Agriculture and Rural Development, Bangladesh Open University, All rights reserved. M. A. Islam et al. Intensive wetland rice cultivation is a common farming practice in Asian countries like Bangladesh. With the expansion of irrigation facilities and the introduction of MV rice, the use of chemical fertilizers for rice production has increased substantially over the last two decades. However, rice farmers usually do not apply balanced doses of N, P, potassium (K), and other fertilizers. Phosphorus fertilizers are seldom applied for rice although P removal from soil continues due to the intensive cultivation. Over the years, P deficiency in rice soils is being observed in many areas, which could be one of the reasons for low rice yields. Ali et al. (1997) reported that in many soils of Bangladesh available P was decreased substantially in 1995 than in 1965. In Bangladesh, P deficiency, especially under lowland rice cultivation, has been identified in the soils of Sonagazi and Motigonj of Feni (Fluvaquents), Barisal (Haplaquents), and Gazipur (Paleudults) (Saleque et al., 1999). Acute P deficiency unexpectedly decreases rice yield. It is very important point to determine the effect of phosphorus on different nutrient uptake at each growth stages of rice without reducing the percentage of ripened grains. The present experiment, was, therefore, undertaken to determine the effects of phosphorus on nutrient uptake pattern of rice. MATERIALS AND METHODS This experiment was conducted at the screen house of Tsukuba International Centre (TBIC), Japan during the 2000 growth season (April-August) in wooden boxes of 1m x 1m x 0.25 m size. Subsoil of an Andisol was used for the experiment, which had high capacity of phosphate fixation. The experimental soil had pH of 6.2, organic C of 1.64%, organic matter of 2.89%, total nitrogen content of 0.18%, available phosphate 0.13 mg P2O5/100 g dry soil, exchangeable potassium 82.7 mg K2O/100 g dry soil, exchangeable calcium 524.65 mg CaO/100 g dry soil and exchangeable magnesium 81.89 mg MgO/100 g dry soil. Two hundred (200) litre air dried subsoil of Andisol were placed in each box. Before placing the soil in the box, fertilizer was mixed up with basal fertilizer. Four levels of phosphorus, viz. 100, 200, 500 and 800 kg P2O5 ha-1 were used in this experiment. Besides phosphorus fertilizer, nitrogen and potassium were -1 applied in each test box at the rates of 120 and 110 kg ha as ammonium sulphate and potassium chloride, respectively. N and K were applied in two splits: basal and topdressing at panicle initiation stage. -I The recommended dose of zinc (24 kg ZnSO4; 7H2O ha ) was dissolved in water and applied to the soil of boxes after levelling and just before the transplanting. The soil in each box was puddled by hand and then kept under submerged condition for three days and made ready for seedling transplanting. One japonica rice variety (Nipponbare) and one indica variety (IR-28) were used for this experiment. The experiment was laid out in a two factor randomized complete block design with three replications. On 17 May 2000, thirty day old seedlings were transplanted at 20 x 20 cm spacing with two seedlings per hill. Plant samples (one hill at each time) for dry matter were collected from different growth stages, viz. seedling stage, 30 days after transplanting (DAT), maximum tillering stage, panicle initiation stage, heading stage and harvesting stage (plant, grain). Content and uptake of phosphorus, nitrogen and potassium were measured at different growth stages. A portion of 0.20 g plant sample was digested with H2SO4 and N was determined after distillation with micro-Kjeldahl distillation apparatus (Yoshida et al., 1976). Another 0.20 g sample wa (...truncated)