Waterlogged Paddy Fields Research Articles

Density and Reserved Leaf Number of Tobacco to be Replanted in Cold Waterlogged Paddy Field

To study the effects of density and reserved leaf number on the growth duration, agronomic character, yield and output value, the test was conducted on the density (Ai): (16665, 13875 and 11895 plants/hm2, respectively) and reserved leaf number (B_j): (26, 22 and 18 pieces, respectively) for planting tobacco in cold waterlogged paddy field. The results showed that: (1) the density has certain effect on the growth duration. The budding period of low density is 1.7-2 days earlier than high density; (2) In the mature period, correlative analysis showed that there was a significant positive correlation between density and plant height (r₃₁ = 0.9992, p<0.01 and there were negative correlation between density and stem girth, total leaf number and maximum leaf area, but not reach significant level; (3) The results showed that there is a positive correlation between density and yield (r₃₁ = 0.9318), but the highest output value was the one whose density was 925 plants/667 m²; (4) Correlative analysis showed that there is a significant positive correlation between reserved leaf number and yield and output value (r₈₁ = 0.9985, p<0.01, r₈₂ = 0.9851, p<0.05); (5) The first five leading yield is A₁B₁, A₂B₁, A₁B₂, A₁B₃, A₂B₂. The first five leading output value is A₂B₂, A₂B₁, A₁B₁, A₁B₃, A₂B₃; (6) Analysis of output value and economic traits of tobacco result showed that the best combination of planting tobacco in cold waterlogged paddy field was 13875 plants/hm²with 22 pieces/plant.

Role of Alternative Electron Acceptors (AEA) to control methane flux from waterlogged paddy fields: Case studies in the southern part of West Bengal, India

The rice fields, depleted of O 2, contain large amount of moisture and organic substrates to provide an ideal anaerobic environment for methanogenesis and are one of the principal anthropogenic sources of methane. In order to mitigate this emission Alternative Electron Acceptors (AEA) were altered in the soil. The experiments were carried out in four seasons at the site of Balarampur, near Baruipur, South 24 Parganas, West Bengal, namely September–December, 2005 (Cultivar: Sundari), February–May, 2006 (Cultivar: Sundari), September–December, 2006 and February–May, 2007 (Cultivar: Swarna-Pankaj). The seasonal average methane flux (Fe treated), for the cultivar type “Sundari” (season: September–December, 2005), is 4.41 t ha −1, as compared to the value of 6.40 t ha −1 for the untreated soil. Similarly for February–May, 2006, the seasonal average methane flux (Fe treated) is 5.52 t ha −1, whereas the untreated flux is 5.69 t ha −1. In the third and fourth seasons we had two treatments with Ammonium Thiosulphate and Ferric Hydroxide. The seasonal average methane flux (treatment: Ammonium Thiosulphate) is 4.35 t ha −1 and 5.41 t ha −1 respectively, whereas for the ferric hydroxide treated soil it is 4.35 t ha −1 and 6.14 t ha −1 respectively. The properties related to the nutrient quality of the harvested paddy seeds supplement these results.

Rhizosphere dynamics of inoculated cyanobacteria and their growth-promoting role in rice crop.

Nitrogen fixing cyanobacteria are the predominant flora in waterlogged paddy fields which contribute significantly towards nitrogen budgeting in these ecosystems. Their establishment and role in plant growth promotion and soil microbial activity is poorly known. Under greenhouse conditions, pots were inoculated with one of a set of twenty cyanobacterial strains isolated from the rhizosphere of diverse rice and wheat varieties. Several strains established in the soil and persisted up to the harvest stage in soil and roots, significantly enhancing soil microbial biomass carbon, available nitrogen, and related soil microbiological parameters, and increased grain yields and grain weight. This can help in selecting promising strains for developing carrier-based inoculants to promote the growth of crop and soil microflora, leading to enhanced soil fertility and crop yields.

Land-Use Management and Wet-Rice Cultivation (Jebi Aji) by the Apatani People in Arunachal Pradesh, India

The traditional knowledge and expertise of the Apatani group of villages in the Ziro valley of Arunachal Pradesh in north-east India were evaluated in terms of the cultural and social cohesiveness associated with managing the land, water and agro-biodiversity. Unlike other tribal communities in north-east India, who mainly practise shifting cultivation, the Apatani depend mainly on perennial wet-rice cultivation. They successfully grow 16 varieties of rice in the waterlogged paddy fields by means of organic farming and appropriate use of diverse natural resources. The traditional wet-rice farming system is functional even today and is modified by the community as and when required. Apatani land-use management is conducted using well tried traditional land law systems, and land is classified into 10 major categories on the basis of traditional uses. The paper also highlights the traditional irrigation technology and techniques for maintaining soil fertility and storing grain.

Aerenchyma and an inducible barrier to radial oxygen loss facilitate root aeration in upland, paddy and deep-water rice (Oryza sativa L.).

The present study evaluated waterlogging tolerance, root porosity and radial O(2) loss (ROL) from the adventitious roots, of seven upland, three paddy, and two deep-water genotypes of rice (Oryza sativa L.). Upland types, with the exception of one genotype, were as tolerant of 30 d soil waterlogging as the paddy and deep-water types. In all but one of the 12 genotypes, the number of adventitious roots per stem increased for plants grown in waterlogged, compared with drained, soil. When grown in stagnant deoxygenated nutrient solution, genotypic variation was evident for root porosity and rates of ROL, but there was no overall difference between plants from the three cultural types. Adventitious root porosity increased from 20-26 % for plants grown in aerated solution to 29-41 % for plants grown in stagnant solution. Growth in stagnant solution also induced a 'tight' barrier to ROL in the basal regions of adventitious roots of five of the seven upland types, all three paddy types, and the two deep-water types. The enhanced porosity provided a low resistance pathway for O(2) movement to the root tip, and the barrier to ROL in basal zones would have further enhanced longitudinal O(2) diffusion towards the apex, by diminishing losses to the rhizosphere. The plasticity in root physiology, as described above, presumably contributes to the ability of rice to grow in diverse environments that differ markedly in soil waterlogging, such as drained upland soils as well as waterlogged paddy fields.

PRESENCE OF hemA-LIKE AND hemT-LlKE GENES IN A JSUMBER OF ANOXYGENIC PHOTOSYNTHETIC BACTERIAL ISOLATES FROM INDONESIA AND SOIL SAMPLES FROM BOGOR AREA

The Rhodobacter sphaeroides hemA and hemT are known to encode a distinct 5-aminolevulinic acid (ALA)-synthase isozyme. This enzyme catalyzes the first and rate limiting step in ALA biosynthesis through the C4 pathway. This study was carried out to detect hemA-\\ke and hemT-\\ke genes in twenty Anoxygenic Photosynthetic Bacterial (APB) isolates from several wetland areas in Indonesia, and four DNA samples that were isolated from four soil samples obtained from Bogor area. Hybridization techniques of Southern and dot blot were used, using hemA and hemT fragment as probes. Southern hybridization analyses indicated the presence of hemA-\\ke gene in five of APB isolates, i.e., MB15, MB16, MB21.2, MB55 and MB6, whereas hemT-\\ke gene was detected only in MB15. Dot blot hybridization analyses suggested that the soil samples from waterlogged paddy-field, dry paddy-field as well as a mud pond were predominantly occupied by prokaryotic organisms which harboured hemA-]\ke gene. However, /iem7"-like sequences were also found in soil sample from dry paddy-field. Key words:Â Â Â hemA-\\ks gene / hemT-\\ke gene / Southern hybridization analysis / dot blot hybridization analysis.

Microscopic observation of the decomposition process of leaf sheath of rice straw and colonizing microorganisms during the cultivation period of paddy rice

Microorganisms colonizing the leaf sheaths of rice plants placed in a waterlogged paddy field were studied using a scanning electron microscope. Decomposition was faster on the adaxial side than on the abaxial side of the leaf sheaths. The veins and trichomes were highly resistant to microbial decomposition throughout the waterlogged period of rice growth. The decomposition and disintegration of leaf sheaths markedly progressed from the third month (from July) after the placement in the paddy field. Microbial colonization was gradual in the first month after the placement of leaf sheaths in the field. One of the common first colonizers had a terminal endospore (Clostridium dissolvens-like microorganisms). Microbial colonization proceeded actively in the second month, and microbiota became diversified. Microbial colonization on the adaxial surface was more than that on the abaxial surface. Respective microorganisms colonized the surfaces separately from each others in this period. They grew mainly on the thin membrane that covered the epidermal layer. Microbial colonies spread all over the abaxial and adaxial surfaces, and there was no significant difference in the degree of colonization between the abaxial surface and the adaxial surface in the third month (in July). Although separate colonization of the respective microorganisms was common, the co-existence of different microorganisms within a colony was also observed. The thin membrane that covered the epidermal layer and the epidermis seemed to be the main substrate during this period. Co-existence of different microorganisms was a common occurrence in colony formation, and organic debris and remaining tissues of leaf sheaths were assumed to be the major substrates in August. These findings on microbial colonization were well correlated with the findings on the degree of decomposition.

Activity of protease extracted from rice-rhizosphere soils under double cropping of rice and wheat

Abstract Protease-active extracts were prepared from 2 rice-rhizosphere and non-rhizosphere soil samples 3 proteolytic isolates from the soil samples which were taken from water logged paddy fields (Gray Lowland Soils) under double cropping of rice and wheat that had been treated with chemical fertilizer (CF) or organic manure (OM). The activities were assayed and characterized using an artificial substrate, benzyloxycarbonyl-L-phenylalanyl-L-tyrosyl-L-leucine (ZFTL). The protease-active extracts from the rhizosphere and non-rhizosphere of the CF and OM soils (abbreviated as CFR, CFN, OMR, and OMN) showed an optimum pH between 7 and 8. The extracts hydrolyzed ZFTL to Tyr-Leu and Leu; generally, Tyr-Leu was the main reaction product. Activities of all the samples were inhibited by EDTA and p-chloromercuribenzoic acid (PCMB) but not by pepstatin and phenylmethanesulfonyl fluoride (PMSF). These results indicate that the main components of the ZFTL-hydrolases in CFR, CFN, 0MR, and OMN were essentially similar. Optimum pH for the activity of the protease extracted from a Gram negative rod (MNB003)., two actinomycetous isolates (MNA014., MRA017) was about 8, 8, and 8.5, respectively. Extract from the culture of MNB003 hydrolyzed ZFTL to Tyr-Leu., Leu,., the protease activity was inhibited by EDTA., PCMB. Protease activities of the extracts from cultures of the two actinomycetes were inhibited by EDTA but not by PCMB. The extract from culture of MNA014 produced mainly Tyr-Leu from ZFTL while MRA017 produced Leu. Characteristics of the protease activity from cultures of MNB003., MNA014 were similar to those of the enzyme extracted from a paddy field soil under single cropping (Takeuchi., Hayano 1994: Soil Sci. Plant Nutr., 40, 691-695) and from an Andosol under tomato cultivation (Hayano et al. 1987: Biol. Fertil. Soils, 4, 179-183), respectively.

Source of soil protease in paddy fields

Properties of soil proteases and proteases from Bacillus spp. obtained from water-logged paddy fields treated with organic manure or chemical fertilizer or not treated with fertilizer were compared to elucidate the sources of soil proteases. The major extractable soil proteases were metal chelator sensitive neutral proteases that were active in hydrolyzing benzyloxycarbonyl-L-phenylalanyl-L-leucine and benzyloxycarbonyl-L-phenylalanyl-L-tyrosyl-L-leucine. In this respect they resembled extracellular proteases from Bacillus subtilis (six isolates), Bacillus cereus (four isolates), and Bacillus mycoides (three isolates) isolated from the same fields. The major extractable soil protease from the manured field was a serine neutral protease that was active in hydrolyzing casein. It resembled an extracellular protease from B. subtilis (eight isolates) isolated from the same field. Extractable soil proteases accounted for 18–96% of the total soil protease in the aforementioned soil. We concluded that a major source of soil protease in water-logged paddy fields is proteolytic Bacillus spp.Key words: soil protease, metal chelator sensitive neutral protease, serine neutral protease, proteolytic Bacillus spp.