Morpho-physiological responses of cowpea leaves to salt stress (original) (raw)
Revista Brasileira de Engenharia Agrícola e Ambiental, 2020
Salinity affects growth and quality of ornamental plants, but studies on mechanisms of salt tolerance in these plants are scarce, particularly under tropical climate conditions. Thus, the morphophysiological leaf responses of four tropical ornamental species were studied, in order to identify the mechanisms involved in the tolerance to salinity and their potentials to be irrigated with brackish water. The research was conducted in a greenhouse using a completely randomized block design, in a 10 x 4 factorial scheme, with four repetitions. The treatments consisted of ten levels of electrical conductivity of irrigation water (0.5; 1.0; 2.0; 3.0; 4.0; 5.0; 6.0; 8.0; 10.0 and 12.0 dS m-1) and four ornamental tropical species (Catharanthus roseus, Allamanda cathartica, Ixora coccinea, and Duranta erecta). At 30 and 60 days after the beginning of saline treatments (DAST), measurements of leaf gas exchange and chlorophyll index were performed. At 60 DAST, leaf area, specific leaf area, leaf area ratio, leaf succulence, Na + and proline concentrations were measured. The physiological and morphophysiological responses of the leaves indicate that I. coccinea species has high capacity to grow under irrigation with saline water. Its higher tolerance to salinity is related to the lower concentration of Na + in the leaves. Conversely, the sensitivity of D. erecta was associated with high Na + and proline concentrations in leaves. The leaf concentration of proline showed to be an indicator more related to the sensitivity of ornamental plants to salt stress; however this relationship should not be generalized for all ornamental species studied. Respostas morfofisiológicas e mecanismos de tolerância à salinidade em quatro espécies ornamentais perenes sob clima tropical RESUMO: A salinidade afeta o crescimento e a qualidade das plantas ornamentais, mas estudos sobre mecanismos de tolerância ao sal nessas plantas são escassos, particularmente sob condições de clima tropical. Assim, estudaram-se as respostas morfofisiológicas foliares de quatro espécies ornamentais tropicais, a fim de identificar mecanismos envolvidos na tolerância à salinidade e seus potenciais para serem irrigadas com água salobra. A pesquisa foi conduzida em casa-de-vegetação, em delineamento em blocos casualizados, com tratamentos arranjados em esquema fatorial 10 x 4, com quatro repetições. Os tratamentos consistiram de 10 condutividade elétrica da água de irrigação (0,5; 1,0; 2,0; 3,0; 4,0; 5,0; 6,0; 8,0; 10,0 e 12,0 dS m-1) e quatro espécies ornamentais tropicais (Catharanthus roseus, Allamanda Cathartica, Ixora coccinea e Duranta erecta). Aos 30 e 60 dias após o início dos tratamentos salinos (DAST), foram avaliadas as trocas gasosas foliares e o índice relativo de clorofila. Aos 60 DAST foram mensurados: área foliar, área foliar específica, razão de área foliar, grau de suculência, e teores de Na + e de prolina. A análise das respostas fisiológicas e morfofisiológicas foliares indica que I. coccinea apresenta alta capacidade de crescimento sob irrigação com água salina. Sua maior tolerância à salinidade está relacionada à menor concentração foliar de Na +. Por outro lado, a sensibilidade de D. erecta foi associada a elevadas concentrações de Na + e prolina nas folhas. A concentração de prolina se mostrou um indicador mais relacionado à sensibilidade ao estresse salino, porém essa relação não pode ser generalizada para todas as espécies ornamentais estudadas. Palavras-chave: estresse salino, fotossíntese, traços foliares, sódio, prolina 1 cfeitosa@ufc.br (Corresponding author) 2
Current Botany, 2017
This study investigates the impact of salinity (NaCl) on growth and ions accumulation in the leaves of three cowpea genotypes: OU100 and KEB-CP118 from Cameroon and ICV12 from Kenya. Four levels of salinity were used (0mM, 50mM, 100mM and 150mM) and the experiment was carried out in the greenhouse. Growth parameters were measured on 8 weeks old plants. Leaf ions concentrations (Na+, K+, K+/Na+) were determined. It was observed that increasing salinity induced significant increase in Na+ and substantial reduction in the accumulation of K+ in the leave of all genotypes. Pearson’s correlation analysis revealed significant association among most of the growth parameters. Water content in shoots was not affected by salinity for all genotypes; however salinity induced a reduction of water content in the root for ICV12 and OU100 genotypes. Generally, results highlighted that high salt concentrations significantly delayed the growth process. The delay was more pronounced for OU100 genotype...
Physiological and Biochemical Responses of Plants to Salt Stress
2015
Salinity affects plant growth and development in various ways through its impact on photosynthesis, water relations and nutrient absorption. Additionally, the biochemical composition of plants is also affected by salinity through changes in the concentration and type of proteins, amino acids, sugars and other carbohydrates. This paper elucidates with examples the changes that occur in the plant‟s physiological functions and biochemical composition as a result of increased salinity of the plant‟s environment. It is highlighted that the fundamental mechanism of salinity‟s effects on plant function is the increase in the osmotic pressure of the plant‟s environment that inhibits the absorption of water and nutrients. Invariably, salinity inhibits photosynthesis through its effects on stomatal conductance, water and nutrient uptake and decrease in the chlorophyll concentration. Subsequently, higher levels of salinity create an excessive accumulation of salts in plant tissues that causes ...
2012 Brazilian Society of Plant Physiology
2012
The growth and nutrient assimilation was evaluated in CaCl2- and CaSO4-supplemented cowpea plants subjected to salt stress (75 mM NaCl). The salinity significantly reduced the cowpea vegetative growth. The addition of CaCl2 in the growth medium did not significantly affect plant growth, while for the CaSO4, the beneficial effects of Ca 2+ were moderate. Salinity increased the Na+, K+, Cl-, N and P content in the plants, however it decreased the content of Ca2+ and Mg2+. Increases in Ca2+ concentration in the nutrient solution caused decreases in the Na+ and Mg2+ contents and increases in Ca2+, K+, P, and Cl- contents. The supplemental Ca2+ may alleviate the Na+ toxicity and may improve nutritional and ionic balance in cowpea, but it cannot overcome the osmotic effects associated with the increased total salt concentration.