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K. Moody - One of the best experts on this subject based on the ideXlab platform.
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Increasing water productivity and weed supression of wet seeded rice: Effect of water management and rice genotypes
Exp. Agr., 2002Co-Authors: T. P. Tuong, P P Pablico, R Confesor, M Yamauchi, K. MoodyAbstract:Weeds are major constraints to wider adoption of wet seeded rice. Two split-plot experiments on water management during crop establishment of wet seeded rice were conducted in the dry and wet seasons of 1994 to quantify crop stand establishment and weed suppression by herbicides and rice genotypes. The latter consisted of ®ve previously identi®ed hypoxic-tolerant lines and three standard cultivars, sown at approximately 300 seeds m72. The tested hypoxic-tolerant genotypes had superior Seedling growth, but not higher crop stand establishment than the standard ones. Genotypes that had superior crop stand establishment or faster Seedling growth did not necessarily give better weed suppression. Genotypes with high tillering ability were more competitive against weeds. Echinochloa glabrescens dominated the weed ¯ora, especially in farmers' practice and anaerobic seeding (seeding into soft mud), followed by ¯ooding at 7 d after seeding (DAS). The relative proportion of Monochoria vaginalis increased in anaerobic seeding with ¯ooding 3 DAS and seeding into standing water. Pretilachlor+fenclorim e ectively controlled weeds in farmers' practice and anaerobic seedings, and 2,4-D in water seeding. Without herbicide, water seeding and anaerobic seeding ¯ooded 3 DAS reduced dry weed weight by 73±88% compared with farmers' practice. Anaerobic seeding with ¯ooding 7 DAS controlled weeds e ectively when the weed pressure was low (dry season, about 136 gm72 of weed biomass in plots without herbicide) but not when weed pressure was high (wet season, 513 gm72). Water seeding could not sustain high rice yields due to low crop stand population caused by ¯otation of Seedlings. Anaerobic seeding with ¯ooding 3 DAS allowed genotypes to sustain high yield and increased water productivity (rice production per unit volume of water used in the ®eld) without having to use herbicide or with only half of the recommended herbicide rate. The correct water management during the crop establishment stage may e ectively lower the economic and possible runo costs of herbicides without reduction in yield or water productivity.
T. P. Tuong - One of the best experts on this subject based on the ideXlab platform.
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effects of seedbed management and delayed transplanting of rice Seedlings on crop performance grain yield and water productivity
Field Crops Research, 2015Co-Authors: R M Lampayan, T. P. Tuong, J E Faronilo, A J Espiritu, J L De Dios, Ruvicyn Bayot, Crisanta Sunio Bueno, Y HosenAbstract:Abstract Transplanting older rice Seedlings grown in well-managed nursery seedbeds may reduce water input and increase the water productivity of rice. Experiments with a split-split-plot design were conducted at IRRI and PhilRice experiment stations in the 2009 DS, 2009 WS, and 2010 DS to assess the performance of rice in terms of crop growth, grain yield, water input, and water productivity as affected by seedbed management variables such as (1) seedbed seeding rate (SR), (2) Seedling age (SA), and (3) seedbed fertilizer management (F). SR was 25 g m−2 (SR25) and 100 g m−2 (SR100) in 2009, and 25 g m−2 (SR25) and 12.5 g m−2 (SR12.5) in 2010. The three SA treatments tested (SA10: 10 days old, SA20: 20 days old, and SA30: 30 days old) were the same in both years, while the F treatments were zero fertilizer (F0), basal fertilizer only (F1), and basal fertilizer + N topdressing (F2). In 2010, the F0 treatment was replaced with higher N-rate application F3 (basal + doubling the amount of fertilizer N for topdressing in F2). Seedling competition in the seedbed affected total crop duration with late transplanting. After 16 days after sowing (DAS) under high seedbed SR and after 21 DAS under low SR, a 10-days delay in transplanting resulted in an additional 5–6 days in the main field. SA significantly affected grain yield, total water input, and total water productivity. The oldest Seedlings (SA30) consistently resulted in lower yield, but required the lowest water input, and thus resulted in comparable or even better total water productivity in the two dry seasons. SA20 was found to be the critical Seedling age. When SA ≤ SA20, yield was not affected; when SA > SA20, yield was reduced. Lower SR improved the grain yield of SA30 during the DS. Well-fertilized seedbeds have better grain yield than with non-fertilized seedbeds in the DS, even with a higher seeding rate. Lowering seeding density (from 25 g seeds m−2 to 12.5 g seeds m−2) and increasing N topdressing did not enhance grain yield.
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Increasing water productivity and weed supression of wet seeded rice: Effect of water management and rice genotypes
Exp. Agr., 2002Co-Authors: T. P. Tuong, P P Pablico, R Confesor, M Yamauchi, K. MoodyAbstract:Weeds are major constraints to wider adoption of wet seeded rice. Two split-plot experiments on water management during crop establishment of wet seeded rice were conducted in the dry and wet seasons of 1994 to quantify crop stand establishment and weed suppression by herbicides and rice genotypes. The latter consisted of ®ve previously identi®ed hypoxic-tolerant lines and three standard cultivars, sown at approximately 300 seeds m72. The tested hypoxic-tolerant genotypes had superior Seedling growth, but not higher crop stand establishment than the standard ones. Genotypes that had superior crop stand establishment or faster Seedling growth did not necessarily give better weed suppression. Genotypes with high tillering ability were more competitive against weeds. Echinochloa glabrescens dominated the weed ¯ora, especially in farmers' practice and anaerobic seeding (seeding into soft mud), followed by ¯ooding at 7 d after seeding (DAS). The relative proportion of Monochoria vaginalis increased in anaerobic seeding with ¯ooding 3 DAS and seeding into standing water. Pretilachlor+fenclorim e ectively controlled weeds in farmers' practice and anaerobic seedings, and 2,4-D in water seeding. Without herbicide, water seeding and anaerobic seeding ¯ooded 3 DAS reduced dry weed weight by 73±88% compared with farmers' practice. Anaerobic seeding with ¯ooding 7 DAS controlled weeds e ectively when the weed pressure was low (dry season, about 136 gm72 of weed biomass in plots without herbicide) but not when weed pressure was high (wet season, 513 gm72). Water seeding could not sustain high rice yields due to low crop stand population caused by ¯otation of Seedlings. Anaerobic seeding with ¯ooding 3 DAS allowed genotypes to sustain high yield and increased water productivity (rice production per unit volume of water used in the ®eld) without having to use herbicide or with only half of the recommended herbicide rate. The correct water management during the crop establishment stage may e ectively lower the economic and possible runo costs of herbicides without reduction in yield or water productivity.
Brenda Tubana - One of the best experts on this subject based on the ideXlab platform.
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transplanting young Seedlings in irrigated rice fields early and high tiller production enhanced grain yield
Field Crops Research, 2008Co-Authors: Estela Magbujos Pasuquin, Tanguy Lafarge, Brenda TubanaAbstract:Abstract Transplanting rice Seedlings 20 days old or older has been commonly reported to generate an increase in grain yield as a result of higher tiller production. A series of experiments was conducted at the IRRI farm during the dry and wet seasons to quantify, in a range of plant types, the impact of even younger Seedlings and contrasting nursery management on grain yield and to identify plant traits supporting high performance under a given establishment technique. Seedling age at transplanting, ranging from 7 to 21 days, and contrasting nursery types (Seedling tray, dapog, mat nursery, and traditional wet-bed seeding) were evaluated for an elite line, a new plant type and hybrid rice. To avoid any confounding effect, sowing date in the nursery, seed rate and crop management in the main field were all the same. In the two seasons, and for all genotypes and nursery types, transplanting older Seedlings induced a delay in the onset of linear dry matter accumulation and tiller emergence, while the rate of dry matter accumulation and tiller emergence was unchanged. This delay reduced nitrogen content in the Seedlings. Plants recovered quickly, however, after transplanting. The delay also reduced maximum tiller number, and extended crop duration with delayed maximum tillering, flowering and maturity. Grain yield was consistently higher for younger Seedlings, with, in some cases, a difference as large as 1 t ha−1 between 7- and 21-day transplanting. This result was valid for the four genotypes evaluated, with a higher impact during the dry season. In contrast, no significant difference was observed for the influence of nursery type on the timing of tiller emergence and on grain yield. Some differences in Seedling vigor (plant dry weight, specific leaf area, N content), higher in the case of dapog and wet bed, and in maximum tillering, higher in the case of the Seedling tray, however, were observed. But these differences did not have a significant impact on the late increase in crop dry matter and on panicle number at maturity. No significant interaction between Seedling age and nursery management for all genotypes and for all the parameters measured was found. Promoting early tiller emergence as a response to transplanting young Seedlings increased grain yield in all cases despite the associated decrease in tillering efficiency. Extended growth inside the nursery, rather than transplanting shock per se, appeared to be the main reason for delayed tiller emergence in late transplanting.
S. K. Pradhan - One of the best experts on this subject based on the ideXlab platform.
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Early Seedling vigour, an imperative trait for direct-seeded rice: an overview on physio-morphological parameters and molecular markers
Planta, 2015Co-Authors: A. Mahender, A. Anandan, S. K. PradhanAbstract:Main conclusion Rapid uniform germination and accumulation of biomass during initial phase of Seedling establishment is an essential phenotypic trait considered as early Seedling vigour for direct seeded situation in rice irrespective of environment. Enhanced role of carbohydrate, amylase, growth hormones, antioxidant enzymes and ascorbic acid brings changes in vigour and phenotype of Seedling. Abstract Early establishment and demanding life form dominate the surroundings. Crop plant that has better growth overdrives the weed plant and suppresses its growth. Seedling early vigour is the characteristic of seed quality and describes the rapid, uniform germination and the establishment of strong Seedlings in any environmental condition. The phenotype of modern rice varieties has been changed into adaptable for transplanted rice with thirst toward water and selection pressure for semi-dwarf architecture resulting in reduced early vigour. Decreasing freshwater availability and rising labour cost drives the search for a suitable alternative management system to enhance grain yield productivity for the burgeoning world population. In view of these issues, much attention has been focused on dry direct-seeded rice, because it demands low input. A rice cultivar with a strong Seedling vigour trait is desirable in case of direct seeding. However, Seedling vigour has not been selected in crop improvement programmes in conventional breeding due to its complex nature and quantitative inheritance. Molecular markers have been proven effective in increasing selection efficiency, particularly for quantitative traits that are simply inherited. Marker-assisted selection approach has facilitated efficient and precise transfer of genes/QTL(s) into many crop species and suggests a speedy and efficient technique over conventional breeding and selection methods. In this review, we present the findings and investigations in the field of Seedling vigour in rice that includes the nature of inheritance of physio-morphological and biochemical traits and QTLs to assist plant breeders who work for direct-seeded rice.
José María Herranz - One of the best experts on this subject based on the ideXlab platform.
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Effect of burnt wood removal on the natural regeneration of Pinus halepensis after fire in a pine forest in Tus Valley (SE Spain)
Forest Ecology and Management, 1999Co-Authors: Juan José Martínez-sánchez, Jorge De Las Heras, Pablo Ferrandis, José María HerranzAbstract:To determine the effect of burnt tree removal on post-fire natural regeneration of Pinus halepensis, two 2500 m2areas were selected six months after the fire in a totally destroyed mature (>70 years) pine forest. In one area, all the trees were cut down and removed 10 months after the fire and, in the other, all the trees were left standing (control). In each area, 20 permanent plots of 20 m2each were randomly placed, and all Seedlings emerging within them labeled by individual numbered plastic tags. Emergence, mortality, density and growth (height) of 6649 P. halepensis Seedlings were monitored during the first four post-fire years. Seedling emergence was concentrated in the first post-fire autumn-winter period. No positive effect on Seedling emergence was detected as a consequence of burnt trunk dragging and subsequent turning over of soil. Wood removal produced an immediate average Seedling mortality of 33%, and notably increased Seedling mortality during the subsequent summer, probably due to increased exposure of Seedlings to sunlight and the possible debilitation of many individuals by mechanical contact during burnt wood removal. A negative correlation of pine Seedling mortality with height was detected, which increased significantly on wood removal in the third post-fire year. That is, short Seedlings (
