Growth and carbon assimilation limitations in Ricinus communis (Euphorbiaceae) under soil water stress conditions

Abstract

RESUMO -(Crescimento e limitações à assimilação de carbono em Ricinus communis (Euphorbiaceae) sob condições de estresse hídrico do solo). A disponibilidade hídrica pode infl uenciar o ganho de carbono e o crescimento, com grande impacto na produtividade das plantas. Ricinus communis (L.), uma espécie resistente à seca, é uma cultura de grande importância econômica no Brasil, devido ao seu uso na indústria química e para a produção de biocombustíveis. Alguns dos mecanismos envolvidos na resistência à seca desta espécie foram analisados através de um progressivo estresse hídrico em plantas cultivadas em vasos sob condições de casa de vegetação. A suspensão da irrigação por 53 dias decresceu o conteúdo gravimétrico de água no solo e o potencial hídrico das folhas. O crescimento das plantas foi negativamente e signifi cativamente reduzido pelo aumento do défi cit hídrico do solo. Com a suspensão da irrigação, a assimilação de carbono e a transpiração foram reduzidas e permaneceram praticamente constantes ao longo do dia. A análise das curvas A/C i demonstrou o aumento da limitação estomática, indicando que a limitação imposta pelo fechamento dos estômatos é o principal responsável pela redução da fotossíntese. A efi ciência de carboxilação e a taxa de transporte de elétrons não foram afetadas pelo estresse hídrico até 15 dias de suspensão da irrigação. A resistência à seca da mamona parece estar relacionada a uma resposta inicial e pronunciada do crescimento, a um efi ciente controle estomático e a capacidade de manter uma alta taxa de fi xação de CO 2 sob condições de estresse hídrico. Palavras-chave: curvas A/Ci, estresse hídrico, fotossíntese, limitação estomática, padrão diário ABSTRACT -(Growth and limitations to carbon assimilation in Ricinus communis (Euphorbiaceae) under soil water stress conditions). Water availability may infl uence plant carbon gain and growth, with large impacts on plant yield. Ricinus communis (L.), a drought resistant species, is a crop with increasing economic importance in Brazil, due to its use in chemical industry and for the production of biofuels. Some of the mechanisms involved in this drought resistance were analyzed in this study by imposing progressive water stress to pot-grown plants under glasshouse conditions. Water withholding for 53 days decreased soil water gravimetric content and the leaf water potential. Plant growth was negatively and signifi cantly reduced by increasing soil water defi cits. With irrigation suspension, carbon assimilation and transpiration were reduced and remained mostly constant throughout the day. Analysis of A/ C i curves showed increased stomatal limitation, indicating that limitation imposed by stomatal closure is the main factor responsible for photosynthesis reduction. Carboxylation effi ciency and electron transport rate were not affected by water stress up to 15 days after withholding water. Drought resistance of castor bean seems to be related to a pronounced, early growth response, an effi cient stomatal control and the capacity to keep...

Photosynthetic capacity and water use efficiency in Ricinus communis (L.) under drought stress in semi-humid and semi-arid areas

“…Such evidence should be indicative that the plant was under moderate to severe water stress during that period in the semi-arid region. Similar results were found in castor bean plant experiments in greenhouse when subjected to severe water stress (Freitas et al 2011, Sausen andRosa 2010).…”

“…Similar results were found in castor bean plant experiments in greenhouse (Freitas et al 2011, Sausen andRosa 2010), and under salinity (Lima Neto et al 2014, Sun et al 2013). These results indicate that this plant has a high stomatal regulation under field conditions, which can reduce water loss by transpiration and maintain the water status of the plant (Pinheiro and Chaves 2011).…”

“…Among those mechanisms, we can highlight an efficient stomatal control, greater conservation capacity of CO 2 fixation under drought stress (Freitas et al 2011, Sausen andRosa 2010), and water use efficiency (Barros Junior et al 2008). These results are promising, however, information is scarce on experiments under field conditions to better understand the physiological mechanisms, and their interactions with climate factors under temporary drought, in castor beans plants.…”

Drought stress response in Jatropha curcas: Growth and physiology

“…In line with previous findings, our data supports that the main strategy of J. curcas to endure drought stress is via a strict stomatal control (Pompelli et al, 2010;Silva et al, 2010a,b;Díaz-López et al, 2012). This also holds true for other Euphorbiaceae species such as Ricinus communis (Sausen and Rosa, 2010), Hevea brasiliensis and Manihot esculenta (El-Sharkawy, 2007).…”

Boron Supply and Water Deficit Consequences in Young Paricá (<i>Schizolobium parahyba</i> var.<i> amazonicum</i>) Plants

“…The reduction in P N induces a lower of 253 carbon assimilation rate (Chaves and Oliviera, 2004;Machado Filho et al, 2006;Sausen and Rosa 2010). Wang et al (2011) obtained similar results in their study of Pyrus pyrifolia, and they reported a decrease in the P N due to increased B levels.…”