Tolerance to water deficit in young trees of jackfruit and sugar apple

Abstract

-The predawn leaf water potential (Ψ l ), stomatal conductance (g s ), CO 2 assimilation (A), transpiration (E), chlorophyll a fluorescence and leaf metabolite contents (soluble sugars, proteins and free amino acids) of two tropical fruit species grown in a greenhouse were evaluated to determine the effect of induced water stress on young plants. Six month-old jackfruit (Artocarpus heterophyllus Lam.) and sugar apple (Annona squamosa L.) plants were evaluated in 10.0 L pots after eight days of water withholding, imposed by suspension of irrigation. Jackfruit water status was better than sugar apple. Sugar apple plants showed different daily stomatal behavior when well hydrated, compared to jackfruit plants under the same conditions. The gas exchange of both species showed sensibility to high vapor pressure deficit (VPD). However, under water deficit, photochemical efficiency dropped at midday in both treatments (control and water deficit) and both species showed low tolerance to high VPD and light intensity under greenhouse conditions. In contrast, some chlorophyll fluorescence variables showed good photosystem II stability at highest VPD hour (14:00 h). The present results involving carbohydrate metabolic changes revealed an accumulation of soluble sugars; moreover, protein and free amino acid contents in water stressed leaves also increased. These findings suggest an absence of damage to photosynthetic machinery for water deficit period. Jackfruit revealed greater tolerance to water deficit than sugar apple an important feature for commercial crops in northeastern Brazil. Key words -Annona squamosa. Artocarpus heterophyllus. Semi-arid. Tropical fruit. Water relations.Resumo -A condutância estomática (g s ), a assimilação de CO 2 (A), a transpiração (E), a fluorescência da clorofila e o conteúdo foliar de (açúcares solúveis, proteínas e aminoácidos livres) de duas espécies frutíferas tropicais foram avaliados para determinar o efeito do déficit hídrico induzido sobre as plantas da jaqueira (Artocarpus heterophyllus Lam.) e da pinheira (Annona squamosa L.) de seis meses de idade foram cultivadas em potes com capacidade para 10,0 L e foram avaliadas após oito dias de suspensão da irrigação. A jaqueira quando bem hidratada, foi melhor do que a pinheira. Plantas de pinheira apresentaram comportamento diferente quanto à condutância estomática diária quando comparada com as plantas de jaqueira, ambas bem hidratadas. As trocas gasosas de ambas as espécies apresentaram alta sensibilidade ao déficit pressão de vapor (DPV). No entanto, sob déficit hídrico, a eficiência fotoquímica decresceu ao meio-dia em ambos os tratamentos (controle e déficit hídrico) e ambas as espécies apresentaram baixa tolerância ao alto DPV e intensidade da luz em casa de vegetação. Em contrapartida, algumas variáveis de fluorescência de clorofila mostraram boa estabilidade na hora de maior DPV (14:00 h), indicando estabilidade do fotossistema II. Os resultados envolvendo alterações metabólicas revelaram um acúmulo de açúcares solúveis, ...

Physiological and biochemical responses to drought stress in Barbados cherry

“…Alterations in free aminoacid content were verified in two apple cultivars under water deficit, increasing more than 40% in comparison with control plants (Sircelj et al, 2005). Rodrigues et al (2010) also verified an increase in aminoacids in leaves of six-monthold jack-plants and sugar apple plants when subjected to eight days without water. These increases were about 61 and 66% respectively.…”

Physiological and Biochemical Responses of Semiarid Plants Subjected to Water Stress

“…Although the concentration of proline in mature leaves increased in response to water stress, its contribution to the total change in osmotic potential was insignificant (Alves & Setter, 2003). Osmotic adjustment as a tolerance mechanism to water stress in young jackfruit and sugar apple trees was evaluated by Rodrigues et al (2010). They observed an accumulation of solute sugars, followed by an increase in protein and amino acid concentrations in waterstressed leaves.…”

Water relations and some aspects of leaf metabolism of Jatropha curcas young plants under two water deficit levels and recovery

“…The ecophysiological responses in plants adapted to semi-arid regions is of interest (Ribeiro et al, 2009;Rodrigues et al, 2010;Souza et al, 2010), particularly when the species has numerous economic applications, like J. curcas (Maes et al, 2009;Pompelli et al, 2010). Strict stomatal control is common to species of Euphorbiaceae in order to prevent water loss (Elsharkawy, 2007), though such behavior leads to a lack of CO 2 , which in turn changes the electron transport chain (Chaves et al, 2009), leading to oxidative stress that can cause damage to membranes due to reactive oxygen species (ROS) (Pompelli et al, 2010).…”