Comparative energy exchange from cowpeas (Vigna unguiculata (L.) Walp cvs. TC-9-6 and M-28-6-6) with differences in canopy architectures and growth durations at the Orinoco llanos

Jose, Juan; Bracho, Rosvel; Montes, R.; Nikonova, Nina

doi:10.1016/s0168-1923(02)00211-3

Cited by 17 publications

(14 citation statements)

References 56 publications

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“…Induced leaf fall is a widely used strategy to reduce leaf area during drought (Greitner, Pell & Winner 1994; Clifton‐Brown et al . 2002; San Jose et al . 2003) even though no effect on leaf water potential may be visible (Wendler & Millard 1996).…”

Section: Discussionmentioning

confidence: 99%

Functional diversity of photosynthesis during drought in a model tropical rainforest – the contributions of leaf area, photosynthetic electron transport and stomatal conductance to reduction in net ecosystem carbon exchange

Rascher

Bobich

Lin

et al. 2004

Plant Cell & Environment

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The tropical rainforest mesocosm within the Biosphere 2 Laboratory, a model system of some 110 species developed over 12 years under controlled environmental conditions, has been subjected to a series of comparable drought experiments during 2000-2002. In each study, the mesocosm was subjected to a 4-6 week drought, with welldefined rainfall events before and after the treatment. Ecosystem CO 2 uptake rate ( A eco ) declined 32% in response to the drought, with changes occurring within days and being reversible within weeks, even though the deeper soil layers did not become significantly drier and leaf-level water status of most large trees was not greatly affected. The reduced A eco during the drought reflected both morphological and physiological responses. It is estimated that the drought-induced 32% reduction of A eco has three principal components: (1) leaf fall increased two-fold whereas leaf expansion growth of some canopy dominants declined to 60%, leading to a 10% decrease in foliage coverage of the canopy. This might be the main reason for the persistent reduction of A eco after rewatering. (2) The maximum photosynthetic electron transport rate at high light intensities in remaining leaves was reduced to 71% for three of the four species measured, even though no chronic photoinhibition occurred. (3) Stomata closed, leading to a reduced ecosystem water conductance to water vapour (33% of pre-drought values), which not only reduced ecosystem carbon uptake rate, but may also have implications for water and energy budgets of tropical ecosystems. Additionally, individual rainforest trees responded differently, expressing different levels of stress and stress avoiding mechanisms. This functional diversity renders the individual response heterogeneous and has fundamental implications to scale leaf level responses to ecosystem dynamics.Key-words : chlorophyll fluorescence; drought; leaf area; leaf fall; leaf growth; net ecosystem CO 2 exchange; photosynthesis; photosynthetic electron transport; tropical rainforest; tropical trees.Abbreviations : A eco , ecosystem photosynthetic CO 2 uptake rate ( m mol CO 2 m -2 s -1 ); c i , apparent intercellular CO 2 concentration (p.p.m.); ET, ecosystem evapotranspiration (mmol H 2 O m -2 s -1 ); ETR, photosynthetic electron transport rate ( m mol electrons m -2 s -1 ); F 0 , ground fluorescence of the dark-adapted leaf; F m , maximum fluorescence of the dark-adapted leaf; F , fluorescence of the light-adapted leaf; F m ¢ , maximum fluorescence of the light-adapted leaf; F v / F m , pre-dawn potential quantum yield of photosystem (PS) II (

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Section: Discussionmentioning

confidence: 99%

Functional diversity of photosynthesis during drought in a model tropical rainforest – the contributions of leaf area, photosynthetic electron transport and stomatal conductance to reduction in net ecosystem carbon exchange

Rascher

Bobich

Lin

et al. 2004

Plant Cell & Environment

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“…Várias pesquisas foram realizadas com o objetivo de se medir a ET de caupi (ANTONINO et al, 2000;BASTOS et al, 2008;LIMA et al, 2006a;LIMA et al, 2006b;SOUZA et al, 2005) e os componentes do balanço de energia (LIMA et al, 2005b;NEVES et al, 2008;SAN JOSÉ et al, 2003). No entanto, pesquisas que determinaram, simultaneamente, os componentes do balanço de energia e a evapotranspiração do caupi são escassas.…”

Section: Introductionunclassified

Balanço de energia e evapotranspiração de feijão caupi sob condições de sequeiro

Lima¹,

Antonino²,

Lira³

et al. 2011

Rev. Ciênc. Agron.

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5Resumo -Objetivou-se determinar os componentes do balanço de energia (saldo de radiação, fluxos de calor latente, sensível e no solo), a evapotranspiração (ET) e a eficiência no uso de água (EUA) do feijão caupi cultivado sob condições de sequeiro. O experimento foi conduzido numa área de quatro hectares, localizada no CCA/UFPB, Areia, PB (6 o 58'12" S e 35 o 42'15" O e 620 m), durante o período de 22/07/2003 a 17/10/2003. Para a determinação dos componentes do balanço de energia e da ET utilizou-se o método da razão de Bowen, sendo que para isso foi instalada, no centro da área, uma torre micrometeorológica com sensores para medição da temperatura e da umidade relativa, em dois níveis acima do dossel do caupi, além de sensores para a medição do saldo de radiação, da radiação solar global, do fluxo de calor no solo e da precipitação pluvial. Verificou-se que o valor médio da razão saldo de radiação/radiação global (Rn/Rg) foi de 79%, sendo a Rn utilizada, em média, como 65% no fluxo de calor latente (LE/Rn), 23% como fluxo de calor sensível (H/Rn) e 12% como fluxo de calor no solo (G/Rn). Em relação à evapotranspiração, observou-se que o valor total durante o período experimental foi 330,7 mm e o médio de 3,8 mm dia -1 . A produção do caupi foi de apenas 206,0 kg ha -1 , com uma EUA baixa (0,06 kg m -3 ), a qual se deu, provavelmente, devido ao déficit hídrico ocorrido na fase reprodutiva. Palavras-chave -Relações hídricas. Eficiência no uso de água. Razão de Bowen.Abstract -The objective of this study was to assess the energy balance components (net radiation, latent heat flux, sensible heat flux and soil heat flux), evapotranspiration (ET) and water use efficiency (WUE) of cowpea grown under rainfed conditions. The experiment was conducted in a 4 ha area in the CCA, UFPB, belonging to the Municipality of Areia, PB (6 o 58 ' S, 35 o 41 ' W and 620 m) during the period from July, 22 2003 to October, 17 2003. To determine the energy balance components and ET, it was used the Bowen ratio method, and for that, the area was instrumented with a micrometeorological tower containing sensors for measuring air temperature and relative humidity at two levels above the canopy of cowpea. Measurements of net and global radiation, soil heat flux and rainfall were also made. The average value of the net radiation was 79% of the global solar radiation (Rn/Rg), in which 65% appeared as latent heat flux (LE/Rn), 23% as sensible heat flux (H/Rn) and 12% as soil heat flux (G/Rn). The total and average values for actual evapotranspiration were 330.7 mm and 3.8 mm day -1 , respectively. The production of cowpea was only 206.0 kg ha -1 with low WUE (0.06 kg m -3 ), which occurred probably due to water deficit at reproductive stage.

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“…5F). This was surprising, because a greater transpiring surface evidently enhances water loss, and many plant species react to drought by partial or complete abscission of the leaves (Clifton‐Brown et al 2002, Rascher et al 2004, San Jose et al 2003). The above finding is also in contradiction with the idea that slow growth enhances resistance to moderate drought (Polley et al 2002, Tardieu and Simonneau 1998).…”

Section: Discussionmentioning

confidence: 99%

Ecophysiological and morphological parameters related to survival in grass species exposed to an extreme climatic event

Milbau

Scheerlinck

Reheul

et al. 2005

Physiologia Plantarum

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An experiment was performed to elucidate interspecific differences in survival time of grass species subjected to an extreme climatic event. We exposed eight grass species to a simulated heat wave in the field ('free air' temperature increase at 11 C above ambient) combined with drought. We determined whether interspecific differences in survival time were related to the responses of the species to the imposed stress or could be explained by their ecophysiological or morphological characteristics in unstressed conditions. Surprisingly, there was no effect of specific leaf area, but species with a higher total leaf area survived longer. This may arise from a greater water reserve in the plant as a whole, which could delay the desiccation of the meristem, or from reduced evaporation due to a higher leaf area index. Species in which the decrease in light-saturated stomatal conductance (g s ) and photosynthetic CO 2 uptake rate (A max ) was strongly related to the decrease in soil water availability (measured as soil relative water content and stress duration) survived longer than species in which g s and A max likewise declined but responded more to daily fluctuations in irradiance, temperature, and vapor pressure deficit during the heat wave. We, therefore, hypothesize that interspecific differences in stress survival time might be related to the extent to which stomata react to changes in soil water conditions relatively to changes in other environmental and physiological factors. The results suggest that resistance to extremes is governed by other mechanisms than resistance to moderate drought.

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Comparative energy exchange from cowpeas (Vigna unguiculata (L.) Walp cvs. TC-9-6 and M-28-6-6) with differences in canopy architectures and growth durations at the Orinoco llanos

Cited by 17 publications

References 56 publications

Functional diversity of photosynthesis during drought in a model tropical rainforest – the contributions of leaf area, photosynthetic electron transport and stomatal conductance to reduction in net ecosystem carbon exchange

Functional diversity of photosynthesis during drought in a model tropical rainforest – the contributions of leaf area, photosynthetic electron transport and stomatal conductance to reduction in net ecosystem carbon exchange

Balanço de energia e evapotranspiração de feijão caupi sob condições de sequeiro

Ecophysiological and morphological parameters related to survival in grass species exposed to an extreme climatic event

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