Studies on Competition in Rice I. Competition in Mixtures of Varieties

Jennings, Peter R.; Jesús, José de

doi:10.1111/j.1558-5646.1968.tb03455.x

Cited by 85 publications

(46 citation statements)

References 4 publications

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“…The finding of the positive regression coefficient for height in the covariate models is compatible with previous reports for rice (Jennings and de Jesus Jr., 1968; Kawano et al, 1974; Dingkuhn et al, 1999; Jearakongman et al, 2003), which indicated that height was one of the important characteristics for competitiveness when rice was grown with other crops or other rice varieties. Regarding the positive regression coefficients for the covariates based on panicle number, previous studies on weed competitiveness reported that a large number of tillers, which are often closely linked with a large number of panicles, is also an important agronomic trait for competitiveness (Zhao et al, 2006; Saito and Futakuchi, 2009).…”

Section: Discussionsupporting

confidence: 91%

Does Use of Unbordered Plots Affect Estimation of Upland Rice Yield?

et al. 2015

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Advance in crop genomics have led to a demand for more accurate and precise phenotyping of a large number of genotypes for discovering genes and mechanisms underpinning important agronomic traits. The use of unbordered plots for field phenotyping is one approach for reducing the resources needed, but competition effects between neighboring lines may confound varietal performance. Four field experiments were conducted in Benin to examine whether grain yields of 14 diverse upland rice (Oryza sativa spp.) varieties determined in unbordered one‐row or two‐row plots differ from those measured in self‐bordered four‐row plots and to examine if statistical models including covariates based on plant characteristics (height, panicle number, and days to heading) for correcting competition effect can improve the estimation of the yield in unbordered plots. Mean grain yield across all varieties ranged from 118 to 378 g m−2 in four experiments. There was no significant variety × row number interaction effect on grain yield, except for the highest yielding experiment. In that experiment, the variety × row number interaction was significant for one‐row versus four‐row plots, but not for two‐row versus four‐row plots. In one‐row plots in this high‐yielding experiment, the neighborhood covariate model based on panicle number improved residual mean square by 20%, but relative selection intensity by 3% only. Similarly, the covariate models based on height or panicle number in both one‐ and two‐row plots in the other experiments improved just 4%. We conclude that unbordered one‐ or two‐row plots can provide reasonable estimates of grain yield of upland rice without any bias due to competition effects, except for high‐yielding one‐row plots (>350 g m−2).

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Section: Discussionsupporting

confidence: 91%

Does Use of Unbordered Plots Affect Estimation of Upland Rice Yield?

et al. 2015

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“…The same appears true with composite crosses, where in any given year one of the pure lines contributing to the composite may give a higher yield than the composite. However, some varietal mixtures have produced higher yields than were ob tained with any of the contributing varieties grown in pure stands (36,47,125). Jennings' group (124,125) showed with rice mixtures that the leafy types were more successful than dwarfs in mixtures but lower yielding in pure stand.…”

Section: Agricultural Ecosystemsmentioning

confidence: 90%

“…However, some varietal mixtures have produced higher yields than were ob tained with any of the contributing varieties grown in pure stands (36,47,125). Jennings' group (124,125) showed with rice mixtures that the leafy types were more successful than dwarfs in mixtures but lower yielding in pure stand. The effect with soybean mixtures (36) has been generally small, at most a 5 to 10% increase in seed yield.…”

Section: Agricultural Ecosystemsmentioning

confidence: 90%

Agricultural Productivity

Loomis¹,

Williams²,

Hall³

1971

Annu. Rev. Plant. Physiol.

128

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Man's dependence upon food resources from cultivated lands had its genesis some 10,000 years ago, and the resulting technology of crop hus bandry has been the principal factor permitting large increases in human population. The potential for food production in conventional agriculture and in alternative systems is undergoing intensive re-examination now be cause of current rapid population growth and attendant pressures for conver sion of highly productive, cultivated lands to other uses. The develop ment of plant physiology as a discipline has been closely linked to the de velopment of agriculture and agricultural research, so it is well that we attempt to take inventory in this review of how our research relates to cur rent and future problems in agricultural productivity.Let us focus our examination of agricultural ecosystems first upon several constraints which limit us in comparative analyses of diverse systems and which serve to shape research needs.First, agricultural systems are basically photosynthetic systems and hence must be assessed for their efficiency in conversion of solar irradiance in terms of both primary productivity and useful end products. This means focusing not only on basic aspects of photosynthesis at leaf and cellular levels but also at the community level. Responses to crowding, the dynamics of canopy development, and canopy persistence over the growing season become crucial matters. Time itself must be viewed as a resource.Second, the choice of crop species is heavily influenced by factors un related to primary production potential. Food, feed, and fiber preferences and secondary constraints such as pests, ease of culture, and the need for diversity in operations establish economic priorities which frequently over ride consideration of biological efficiency, Thus, in The Netherlands, grasses may accumulate 1000 g m-2 of dry matter before the time that maize can even be planted (210). However, significant amounts of maize are grown in The Netherlands because of its utility as a concentrated carbohydrate source. Also, it appears that genetic selection generally has favored quantity and quality of economic yield, variables which often correlate poorly with community productivity. These same factors encourage the culture of a desirable plant to be extended towards the limits of its climatic adaptation. Thus, economically attractive cropping systems may be transposed to en-431 7518 Annu. Rev. Plant. Physiol. 1971.22:431-468. Downloaded from www.annualreviews.org Access provided by North Dakota INBRE on 11/19/14. For personal use only. Quick links to online content Further ANNUAL REVIEWS

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“…This has been demonstrated with barley (SUNESON, 1949), and dramatically for rice (JENNINGS and DE JESUS, 1968), where it has been shown that high yielding cultivars are suppressed and even totally eliminated in mixturesi.…”

Section: Principles Of Design Of Cereal Ideotypesmentioning

confidence: 92%

The breeding of crop ideotypes

1968

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Most plant breeding is based on "defect elimination" or "selection for yield". A valuable additional approach is available through the breeding of crop ideotypes, plants with model characteristics known to influence photosynthesis, growth and (in cereals) grain production. Some instances of the successful use of model characters of this kind are quoted.It is postulated that a successful crop ideotype will be a weak competitor, relative to its mass. Thus the like plants in the crop community will compete with each other to a minimum degree. This relationship of plant form to the exploitation of the enviroment may lead to two negative relationships among genotypes, namely : (a) Between the performance of cultivars at low density and at high density respectively, and (b) Between the competitive ability of cultivars against other genotypes on the one hand, and their capacity for yield in pure culture on the other.A crop ideotype will make a minimum demand on resources per unit of dry matter produced. Further, in cereals, each unit of dry matter will include such a number of florets as to ensure that the ear has sufficient capacity to accept all photosynthates either from its own green surfaces or from other parts of the plant. These criteria are to be satisfied especially at high fertility, and when the total pressure by the community on environmental resources is intensified by high density of population.A wheat ideotype is described. It has a short, strong stem; few, small, erect leaves; a large ear (this specifically means many florets per unit of dry matter of the tops); an erect ear; awns; and a single culm.The design of crop ideotypes is likely to involve concurrent modifications of the environment. The wheat ideotype here described will call for consideration of the density of planting, the fertilizer rate, the plant arrangement and weed control.Eventually most plant breeding may be based on ideotypes.

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Studies on Competition in Rice I. Competition in Mixtures of Varieties

Cited by 85 publications

References 4 publications

Does Use of Unbordered Plots Affect Estimation of Upland Rice Yield?

Does Use of Unbordered Plots Affect Estimation of Upland Rice Yield?

Agricultural Productivity

The breeding of crop ideotypes

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