Morphological and Anatomical Features of Alfalfa Leaves as Related to CO<sub>2</sub> Exchange<sup>1</sup>

Delaney, R. H.; Dobrenz, A. K.

doi:10.2135/cropsci1974.0011183x001400030033x

Cited by 29 publications

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“…SLA is a parameter that can have a marked impact on the expansion of the leaf area and hence on dry matter accumulation, particularly, in the early stages of growth. SLA could impact on dry matter accumulation because of a negative association between SLA and net CO 2 exchange rate per unit leaf area (Khan and Tsunoda 1970;Delaney and Dobrenz 1976;Dornhoff and Shible 1976), but is more likely to have an impact through a positive association between SLA and the rate of leaf area expansion (Rawson et al 1987;Tollenaar 1989;Hay 1990;Solhaug 1991). As explained by Solhaug (1991), even though high SLA could be associated with reduced net assimilation rate (NAR), the greater leaf expansion associated with high SLA would generally more than compensate for reduced NAR.…”

Section: Discussionmentioning

confidence: 99%

Seeding date, photoperiod and nitrogen effects on specific leaf area of field-grown wheat

Hotsonyame¹,

Hunt²

1998

Can. J. Plant Sci.

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Hotsonyame, G. K. and Hunt, L. A. 1998. Seeding date, photoperiod and nitrogen effects on specific leaf area of field-grown wheat. Can. J. Plant Sci. 77: 51-61. Specific leaf area (SLA), the ratio of leaf area to leaf weight, is an important plant characteristic that affects the rate of dry matter production of crop canopies. It is affected by the conditions of growth of both isolated plants and crop communities, but the extent to which various environmental factors impact on SLA under field conditions is not clearly understood. This study was conducted to study the variability in SLA of leaves on the main culm, and in the leaf canopy as an entity, under different conditions of photoperiod, nitrogen and temperature for a number of wheat genotypes grown under field conditions. Five plantings at approximately bimonthly intervals on 12 May, 5 July and 22 September 1993; and on 9 June and 10 August 1994 were made under both natural photoperiod and an extended photoperiod of 20 h. A split plot design with two levels of nitrogen (0 kg N ha -1 and 150 kg N ha -1 ) as main plots and four genotypes of wheat comprising two spring types (Norseman and Roblin) and two winter types (Ruby and Harus) as subplots was used.SLA of individual leaves varied among leaf positions, but the pattern of variation was dependent on sowing date and genotype. For May and June sowing dates, SLA increased with leaf number up to leaf 5 and then declined with subsequent leaf numbers for the spring genotypes, but increased to leaf 5 and changed little thereafter for the winter types. For July or August sowing and for both spring and winter genotypes, the change in SLA with leaf position was less clear. The results further showed that some of this variability in SLA with leaf position could be accounted for by the mean air temperatures over which the leaves developed. As temperatures increased from 8°C to 26°C, SLA increased to a maximum value achieved at 18-20°C and then declined. However, there was a large scatter of SLA values around 18-20°C, due partly to some lower SLA values for the July and August sowing dates. This suggests the impact of other factors such as radiation and the degree of mutual shading within the canopy on SLA. Mean canopy SLA reflected the individual leaf values during the period of leaf production, and varied with sowing date and genotype, although the pattern of genotypic variability was inconsistent over sowing dates; it decreased rapidly after spike emergence presumably reflecting leaf aging. Neither nitrogen nor photoperiod had significant effects on SLA on both individual leaf and canopy bases.The results suggest that temperature is one factor affecting SLA under field conditions, but that further work to identify other factors impacting on SLA in the field will be necessary. For application of simulation models to situations in which temperatures are likely to vary, an accounting for the impact of temperature on the SLA of individual leaves would be desirable.Key words: Specific leaf area (SLA), sowing date, tempera...

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Section: Discussionmentioning

confidence: 99%

Seeding date, photoperiod and nitrogen effects on specific leaf area of field-grown wheat

Hotsonyame¹,

Hunt²

1998

Can. J. Plant Sci.

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“…Positive associations between rate of net photosynthesis (P,) and S, have been recorded in ryegrass, oat, soybean and lucerne (Wilson and Cooper 1969;Dornhoff and Shibles 1970;Criswell and Shibles 1971;Delaney and Dobrenz 1974). Wilson and Cooper (1969) found that in ryegrass genotypes, temperature caused changes in leaf thickness and mesophyll cell size, but these changes were not closely associated with changes in potential P,.…”

Section: ("C)mentioning

confidence: 99%

Effect of Temperature on Growth of Five Subtropical Grasses. I. Effect of Day and Night Temperature on Growth and Morphological Development

Ivory¹,

Whiteman²

1978

Functional Plant Biol.

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Cenchrus ciliaris, Chloris gayana, Panicum maximum var, trichoglume, Panicum coloratum var. makarikariense and Pennisetum clandestinum were grown in two experiments in controlled environments, each experiment having all possible daylnight temperature combinations of (1) 10, 20, 30, and 40°C and (2) 15,25, 30 and 35°C. Both day and night temperatures significantly affected growth in all species. Growth was greatly restricted by constant temperatures of 10 and W C , while maximum growth rates occurred at 29-35°C day temperatures with 26-30°C night temperatures. At optimum or supra-optimum temperatures a diurnal variation in temperature gave higher growth rates than a constant temperature for the same daily mean. By contrast, at suboptimum temperatures a constant temperature gave the highest growth rates and growth rate was decreased as the diurnal variation about a given daily mean temperature was increased.Mathematical functions relating the growth of each species to day and night temperature and maximum growth rate at optimum temperatures were developed.The effect of temperature on relative growth rate (Rw) was mediated through its effect on net assimilation rate (EA). Night temperature was found to affect Rw and EA independently of day temperature and therefore a prehistory effect of night temperature on photosynthesis in the subsequent day was indicated.Temperature had significant effects on tillering in P. maximum and P. clandestinum but had little effect in C. gayana, C. ciliaris and P. coloratum. The optimum temperatures for leaf growth and leaf area development in C. ciliaris and C. gayana were higher than the optimum temperatures for growth of the whole plant, while optimum temperatures for stem growth were lower. In P. maximum, P. coloratum and P. clandestinum, optimum temperatures for all growth components were similar.Differences between temperate and tropical grasses in morphological reaction to temperature are discussed.

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“…In determining photosynthetic rates, leaf characters such as leaf weight and leaf area play a major role (Delaney and Dobrenz 1974). Specific leaf weight (SLW) is one leaf character correlated positively with carbon exchange rate (CER) (Delaney and Dobrenz 1974). but no relationship between leaf area (LA) and SLW was found in alfalfa (Bhagsari and Brown 1986).…”

Section: Introductionmentioning

confidence: 99%

Factors Affecting Growth and Harvest Index in Pea (Pisum sativum L.) Varieties Differing in Time of Flowering and Maturity

Chandra

Polisetty

1998

J Agronomy Crop Science

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Three varieties of Pea (Pimm sativum L.) viz. EC33866 (early). P-i 16 (medium) and T-163 (late), differing in their flowering and maturity times, were taken for this study. The early variety recorded lower dry matter, COj exchange rate and lower yield. The harvest index (HI) was the highest (44 %) in this variety. Though medium and late varieties did not differ significantly in dry matter accumulation and pod yield, they diflered in their HI. The HI in the medium variety is 42 % but in the late variety it is only 36%.The late variety maintained high leaf area, leaf dry weight, high shoot/root, shoot/nodule and root/nodule ratios, increased nodule dry weight and maximum glycolate oxidase activity. But acetylene reduction activity was low, and the harvest index was lowest. On the other hand, in the early variety the dry matter accumulation was lowest but Hi was highest. The major reasons for high HI in this variety were translocation of photosynthates to reproductive organs and lower photorespiration as indicated by low glycolate oxidase activity.

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Morphological and Anatomical Features of Alfalfa Leaves as Related to CO₂ Exchange¹

Cited by 29 publications

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Seeding date, photoperiod and nitrogen effects on specific leaf area of field-grown wheat

Seeding date, photoperiod and nitrogen effects on specific leaf area of field-grown wheat

Effect of Temperature on Growth of Five Subtropical Grasses. I. Effect of Day and Night Temperature on Growth and Morphological Development

Factors Affecting Growth and Harvest Index in Pea (Pisum sativum L.) Varieties Differing in Time of Flowering and Maturity

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Morphological and Anatomical Features of Alfalfa Leaves as Related to CO2 Exchange1

Cited by 29 publications

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Seeding date, photoperiod and nitrogen effects on specific leaf area of field-grown wheat

Seeding date, photoperiod and nitrogen effects on specific leaf area of field-grown wheat

Effect of Temperature on Growth of Five Subtropical Grasses. I. Effect of Day and Night Temperature on Growth and Morphological Development

Factors Affecting Growth and Harvest Index in Pea (Pisum sativum L.) Varieties Differing in Time of Flowering and Maturity

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Morphological and Anatomical Features of Alfalfa Leaves as Related to CO₂ Exchange¹