RESEARCH AND APPLIED TECHNOLOGY
RECHERCHE ET TECHNOLOGIE APPLIQUÉE
INVESTIGACIÓN Y TECNOLOGÍA APLICADA
M. Badruddin and M. Shafiqullah
Bangladesh Institute of Nuclear Agriculture, PO Box No. 4, Mymensingh 2200, Bangladesh
Sulphur is considered as the fourth major nutrient element for crops (Platou and Jones, 1982). Accumulation of inorganic nitrogen or organic non-protein nitrogen in the tissue, leaf area, seed number/plant-1, floral initiation and anthesis in plants may be affected by the presence or absence of sulphur (Hocking, 1987; Janzen and Bettany, 1984; Onkeresingh and Nandlal, 1987; Tiwari, 1994). Sulphur also influences the growth rate and root:shoot ratio in plants (Clarkson, Saker and Parvez, 1989). The contents of plant protein, chlorophyll and photosynthetic carbon dioxide fixation may also be affected by sulphur (Qi, 1989; Hall et al., 1972). Stewart and Porter (1969) reported that lack of sulphur in the plant environment limits the efficiency of applied nitrogen and sulphur nutrition is necessary to achieve the maximum utilization of applied nitrogen. Nitrogen and sulphur fertilization increase the concentration of each other along with increased protein level (Walker and Booth, 1992). Sulphur in plant tissue can reflect the relative availability of nitrogen and sulphur for protein synthesis (Metson, 1973).
This experiment was conducted to find out the differences in sulphur uptake efficiency in rice mutants/varieties developed by Bangladesh Institute of Nuclear Agriculture, Mymensingh. The rice genotypes Binadhan 4, Binadhan 6, Binadhan 5, RM250-124 and the check varieties BR14, BR 11 and Pajam were used in the study. A complete randomized design was followed, together with three replications. Rice seedlings were grown in sand in polyvinylchloride (PVC) pots. Thirty-day-old seedlings were tested for 35S uptake. For this purpose, seedlings were uprooted carefully from the pots to avoid damaging the roots and the roots were washed in running water to remove the sand. The seedlings were then placed on pieces of hardboard with holes cut out of them. The pieces of hardboard were placed on PVC pots containing 0.1 percent strength nutrient solution (Hewitt, 1966) along with 30 µCi 35S. Aeration to the nutrient solution was maintained throughout the experiment. After six hours, samples of the seedlings were taken from the solution. Roots and shoots were separated immediately after collection. Fresh shoot samples were boiled for 15 minutes in a water bath for extraction of 35S. This was repeated twice, and a final volume of 20 ml was extracted. One ml of the aliquot from each test tube was taken in separate vials for 35S analysis. To each vial was added 9 ml of scintillate (prepared by dissolving 8 g of POPOP and 0.5 g of PPO in 1 litre of toluene and 500 ml of triton-x-100). Counts were taken in a b-counter (model LSC, N.E. Technology, United Kingdom). Counts of a set of standards were also taken. 35S uptake was calculated against the standards and was expressed as nCi 35S uptake/minute-1.
The results indicated that the varieties studied can be divided into a high sulphur uptake group and low sulphur uptake group. Among the high uptake group, BR14 ranked highest followed by Binadhan 4, Binadhan 6 and Binadhan 5 (Figure 1). BR11 had the lowest 35S uptake efficiency. A similar variation in sulphur uptake was reported in maize by Saccomani and Ferrari (1989). They reported that the low yield group of maize has the lowest capacity to take SO42- while the high yield group has high sulphate uptake efficiency.
Sulphur uptake by rice genotype
It has been reported that BR14, Binadhan 4 and Binadhan 6 are high-yielding genotypes, with longer panicle lengths than those of the other genotypes studied (Bangladesh Institute of Nuclear Agriculture, 1997). Dreyfus (1964) reported that sulphur uptake in plants is genetically controlled. In the present study it was found that there was variability in sulphur uptake efficiency among the genotypes. It has been reported that in sulphur-supplied plants the leaf area is higher than that in sulphur-deficient plants (Tiwari, 1994). The increased leaf area may fix more carbon dioxide, which may influence the rate of photosynthesis. Clarkson, Saker and Parvez (1989) reported that the root:shoot ratio was higher in sulphur-supplied plants than that in sulphur-deficient plants. So when sulphur is readily available the growth of the root and the shoot may be enhanced, leading to the enhanced dry matter accumulation. In the present experiment, the significance of the developed characteristics of the high sulphur uptake group might be that the larger quantities of sulphur taken up by the rice plants may enhance their physiological functioning. Larger quantities of sulphur may take part in the synthesis of amino acids, and other assimilates in higher amounts may result in more filled grains and higher yield (Bangladesh Institute of Nuclear Agriculture, 1998). It has been found that a high rate of sulphur in maize increased the accumulation of nitrogen, thereby increasing yields (Rabuffetti and Kamprath, 1977).
From the overall results of the study, it may be argued that sulphur plays a role in determining the growth and yield of rice. The tool of 35S may be used as one of the criteria for identifying rice genotypes for higher yield.
Bangladesh Institute of Nuclear Agriculture. 1997. Annual Report. 1994-1995. Mymensingh, Bangladesh Institute of Nuclear Agriculture, p. 2-6.
Bangladesh Institute of Nuclear Agriculture. 1998. Annual report. 1995-1996. Mymensingh, Bangladesh Institute of Nuclear Agriculture, p. 31-7.
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Étude comparative de l'efficacité de la fixation du soufre des différents génotypes de riz
L'absence de soufre dans le milieu végétal limite l'efficacité de l'azote utilisé et l'adjonction de S est nécessaire pour obtenir une utilisation maximale de l'azote appliqué. Cette expérience a été menée pour déterminer les différences d'efficacité de la fixation du soufre dans le riz. Les résultats montrent qu'il y aurait une variabilité de l'efficacité de la fixation de S selon les génotypes et les variétés de riz peuvent être subdivisées en groupes à forte fixation de S et groupes à faible fixation de S. Le soufre absorbé par les plants de riz en quantité supérieure peut améliorer le fonctionnement physiologique de ces plants. Le 35S peut être utilisé comme outil pour identifier les génotypes de riz pour un accroissement des rendements.
Estudio comparado de la eficacia en la absorción de azufre de los genotipos del arroz
La falta de azufre en el entorno de la planta limita la eficacia del nitrógeno aplicado. La aportación de azufre es necesaria para conseguir el máximo aprovechamiento del nitrógeno que se emplea. Este experimento se realizó para descubrir las diferencias de eficacia en la absorción de azufre del arroz. Los resultados indican que la eficacia en la absorción de azufre de los distintos genotipos varía, y que las variedades de arroz pueden dividirse en un grupo de elevada absorción y otro de baja absorción. Una mayor absorción de azufre puede mejorar el funcionamiento fisiológico de las plantas. El 35S puede utilizarse como herramienta para identificar los genotipos del arroz, con el objetivo de conseguir un rendimiento mejor.