Ecological significance of rice (Oryza sativa) planting density and nitrogen rates in managing the growth and competitive ability of itchgrass (Rottboellia cochinchinensis) in direct-seeded rice systems

Rice (Oryza sativa L.) is first staple crop of Nepal. The national average yield of rice is less than its potential yield, for which poor agronomic management has been reported as the critical factor. Among various agro-management practices seedling age, seeding density and nitrogen rates significantly affect the growth and yield of rice. The lower seeding density produces the taller plant, more effective tiller, lower sterility and higher grain yield. On the other hand, seedling of older age from higher seeding density gives the lowest yield. Transplanting younger seedling with low seeding density and application of recommended dose of nitrogen gives a higher yield. This article summarizes various effects of seedling age, seeding density and nitrogen rates on plant height, number of effective tillers, number of filled grains, thousand grain weight and grain yield of rice. This information may be useful for maize growers and researchers.

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Effect of nitrogen rates and weed control methods on weeds abundance and yield of direct-seeded rice

Archives of Agronomy and Soil Science ◽

10.1080/03650340903369384 ◽

2011 ◽

Vol 57 (3) ◽

pp. 239-250 ◽

Cited By ~ 32

Author(s):

Gulshan Mahajan ◽

Jagadish Timsina

Keyword(s):

Weed Control ◽

Control Methods ◽

Direct Seeded ◽

Nitrogen Rates

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A potential retardant for lodging resistance in direct seeded rice (Oryza sativa L.)

Canadian Journal of Plant Science ◽

10.4141/cjps2011-089 ◽

2012 ◽

Vol 92 (1) ◽

pp. 13-18 ◽

Cited By ~ 10

Author(s):

Uma Rani Sinniah ◽

Sri Wahyuni ◽

Bambang Surya Adji Syahputra ◽

Saikat Gantait

Keyword(s):

Oryza Sativa ◽

Cell Walls ◽

Foliar Application ◽

Oryza Sativa L ◽

Parenchyma Cell ◽

Growth Retardant ◽

Lodging Resistance ◽

Bending Resistance ◽

Stem Bending ◽

Direct Seeded

Sinniah, U. R., Wahyuni, S., Syahputra, B. S. A. and Gantait, S. 2012. A potential retardant for lodging resistance in direct seeded rice ( Oryza sativa L.). Can. J. Plant Sci. 92: 13–18. Yield losses in rice are heavy, particularly when lodging occurs after heading. A major contributing factor towards lodging is the tall phenotypic characteristic of the plant. In rice, application of growth retardant can reduce plant height by means of internode retardation. In this study, paclobutrazol at 50, 100 and 200 ppm was applied as a foliar application at panicle initiation on MR 219 and MR 84 cultivars and its effects on growth, lodging resistance and yield were studied. Foliar-applied growth retardant inhibited plant growth and retarded internode and culm length but increased culm diameter. All treated plants had higher bending resistance compared with the control. A significant positive correlation was observed between increased culm diameter and stem bending resistance (r=0.885). Histological studies showed greater compaction of parenchyma cells with thickening of parenchyma cell walls. Treatments with either 50 or 100 ppm paclobutrazol gave significant retardation of internodes and gave higher stem bending resistance with significant increase in yield.

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Exploring agronomic strategies to improve oat productivity and control weeds: leaf type, row spacing, and planting density

Canadian Journal of Plant Science ◽

10.1139/cjps-2017-0354 ◽

2018 ◽

Vol 98 (5) ◽

pp. 1084-1093 ◽

Cited By ~ 3

Author(s):

Pufang Li ◽

Fei Mo ◽

Defeng Li ◽

Bao-Luo Ma ◽

Weikai Yan ◽

...

Keyword(s):

Crop Production ◽

Competitive Ability ◽

High Density ◽

Weed Suppression ◽

Planting Density ◽

Row Spacing ◽

Environment Interaction ◽

Weed Biomass ◽

Intermediate Density ◽

Erect Leaf

The trade-off between crop production and weed control is a fundamental scientific issue, as it is frequently influenced by individual crop competitive ability, population density, and planting pattern. A 2 yr field study was conducted to examine the relationship between planting density and row spacing, using two contrasting oat varieties. On average, high planting density (480 plants m−2) reduced weed biomass at oat maturity by 59% in 2012 and by 56% in 2013, when compared with a low density (120 plants m−2). The droopy-leaf variety suppressed weed biomass by up to 69% and weed density up to 72%, compared with the erect-leaf variety. In a drier year, the greatest grain yield was achieved with the droopy-leaf variety under the intermediate density, while in 2013, the erect-leaf variety under the high density had similar yield to the droopy-leaf variety at the intermediate density. A general trend was that increasing plant density suppressed weed infestation, and promoted crop biomass and yield. The droopy-leaf variety exhibited a strong competitive ability under the intermediate planting density, while the erect-leaf variety had a strong competitive ability under the high density. Taken together, there was a complex variety-by-environment interaction to achieve the balance between crop production and weed suppression, which was mediated by growing-season conditions.

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