Growth evaluation and water relations of Erythrina velutina seedlings in response to drought stress

Abstract

Erythrina velutina Willd. (common name: mulungu) is a deciduous, heliophyte found in the semi-arid region of northeastern Brazil. To evaluate the growth and water relations of mulungu seedlings in soils with different degrees of moisture content, an experiment was carried out under greenhouse conditions using four water treatments (100%, 75%, 50% and 25% of the field capacity-FC). Predawn (Ψ pdw ) and midday leaf water potential (Ψ mdw ), relative water content (RWC), plant height, number of leaves, stem diameter, leaf area (LA), specific leaf area (SLA), leaf area ratio (LAR), dry matter in different organs, biomass partitioning and root:shoot ratio were evaluated. No differences were detected between treatments for Ψ pdw after 30 days; however, at midday, control plants and those under 75% FC underwent a greater reduction in Ψ mdw than plants cultivated with 50% and 25% FC. After 90 days, only the plants under 50% FC exhibited a reduction in Ψ mdw . RWC was reduced at midday, but there were no differences between treatments. Nearly all growth parameters were reduced due to water deficit, especially in the plants with 25% FC, as determined by the number of leaves, stem diameter, plant height, LA, SLA and dry mass in several organs. LAR and root:shoot ratio were not affected. Mulungu seedlings seem to have developed rusticity to overcome intermittent droughts with no change in the pattern of dry matter distribution. The maintenance of turgor pressure seems to be more associated to a reduction in the growth ratio than a reduction in leaf water potential.Key words: biomass allocation, dry matter, leaf area, root to shoot ratio, relative water content, water potential RESUMO Erythrina velutina Willd. (comumente chamada mulungu) é uma espécie decídua, heliófita, encontrada nas regiões semi-áridas do Nordeste do Brasil. Com o objetivo de avaliar o crescimento e as relações hídricas de mudas de mulungu cultivadas em solo com diferentes graus de umidade, foi desenvolvido um experimento em condições de casa de vegetação utilizando quatro tratamentos hídricos (100%, 75%, 50% e 25% da capacidade de campo-CC). Foram avaliados o potencial hídrico foliar antes do amanhecer (Ψ pdw ) e ao meio-dia (Ψ mdw ), o teor relativo de água (TRA), altura das plantas, número de folhas, diâmetro do caule, área foliar (AF), Braz. J. Plant Physiol., 22 (4) área foliar específica (AFE), razão de área foliar (RAF), matéria seca para os diversos órgãos, partição de biomassa e relação raiz/ parte aérea. Não foram encontradas diferenças significativas para Ψ pdw após 30 dias; Entretanto, ao meio-dia, as plantas controle e aquelas sob 75% CC sofreram uma maior redução no Ψ mdw do que as plantas cultivadas com 50% e 25% CC. Após 90 dias, apenas as plantas sob 50% CC exibiram reduções no Ψ mdw . O TRA foi reduzido ao meio-dia, mas não foram observadas diferenças entre os tratamentos. O déficit hídrico reduziu quase todos os parâmetros de crescimento, especialmente nas plantas cultivadas com 25% CC, como observado para o número de folhas, di...

Growing Pereskia aculeata under intermittent irrigation according to levels of matric potential reduction

“…Therefore, the difficulty of "Ora-pro-nobis" plants to absorb water from the substrate increased gradually with each unit of matric potential reduction, resulting in signs of water deficit stress such as reduced growth. Similar results were obtained in many experiments, with forestry species, flowers and cactus (Figueirôa et al 2004, Snyman 2004, Álvarez et al 2009, Silva et al 2010, Martins et al 2010.…”

“…Plants subjected to water deficit usually have significant mass reduction, as observed in Myracrodruon urundeuva (Figueirôa et al 2004), Azadirachta indica (Martins et al 2010), Erythrina velutina (Silva et al 2010) and Opuntia cactus (Snyman 2004). Drought also causes higher allocation of photosynthates to roots than shoots (Kozlovski & Pallardy 2002, Silva & Nogueira 2003, stomatal closure, leaf growth inhibition, osmostic adjustment (Chaves et al 2002, Silva et al 2009 and changes in tissue elasticity (Kozlovski & Pallardy 2002, Tardieu et al 2011.…”

“…Drought also causes higher allocation of photosynthates to roots than shoots (Kozlovski & Pallardy 2002, Silva & Nogueira 2003, stomatal closure, leaf growth inhibition, osmostic adjustment (Chaves et al 2002, Silva et al 2009 and changes in tissue elasticity (Kozlovski & Pallardy 2002, Tardieu et al 2011. Skirycz & Inzé (2010) emphasize that under abiotic stresses plants actively re-program their growth, recover it and adapt themselves, once stress conditions become stable.…”

Bio fertilizers and zinc effects on some physiological parameters oftriticaleunder water-limitation condition

“…To evaluate plant water status, the leaf water potential and relative water content are essential parameters that are generally used to study plant physiological responses to drought stress (Silva et al 2010). Silva et al (2010) stated that these parameters decrease in most plants under water deficit.…”

“…Silva et al (2010) stated that these parameters decrease in most plants under water deficit. Decrease in RWC in plants under drought stress may depend on plant vigor reduction and have been observed in many plants (Liu et al 2002).…”