Comparative Effects of NaCl and Polyethylene Glycol on Germination, Emergence and Seedling Growth of Cowpea

Abstract

Seeds of Pacen˜o and Cuarenten˜o cultivars of cowpea (Vigna unguiculata L. Walp.) were tested for salt and drought tolerance at germination, seedling emergence and early seedling growth in NaCl and PEG-8000 solutions of different osmotic potentials (0, )0.2, )0.4, )0.6, and )0.8 MPa). Daily and final germination and emergence percentage, as well as germination and seedling emergence rate, and seedling growth were recorded under controlled conditions. Results showed that germination and emergence rate were delayed by both solutions in both cultivars, with differences between cultivars among growth stages, given that cultivar Cuarenten˜o, showed a higher germination rate than Pacen˜o in NaCl, but Pacen˜o was less affected by NaCl and PEG solutions at the emergence stage. Sodium chloride had a lesser effect on both cultivars in terms of germination rate, emergence rate and the final germination and emergence percentage than did PEG-8000. This conclusively proves that the adverse effect of PEG-8000 on germination, emergence and early seedling growth was due to the osmotic effect rather than the specific ion. Seedling growth was reduced by both stresses, but NaCl usually caused less damage than PEG to cowpea seedlings, suggesting that NaCl and PEG acted through different mechanisms.

Response of durum wheat (Triticum durum Desf.) growth to salt and drought stresses

“…The results obtained in this study revealed that dry weights were less affected than fresh weights and are in agreement with the results obtained by Murillo-Amador (2002) in cowpea. The effect of PEG on the leaf area of 10-days-old plants was greater than that on fresh and dry weights and plant height (Figure 4).…”

“…Moreover, salt and water stresses are responsible for either inhibition or delayed seed germination and seedling establishment (Bewley & Black 1994). Under stress conditions, the germination of seeds is affected by creating an external osmotic potential that prevents water uptake or due to the toxic effects of Na + and Cl -ions both during imbibition and seedling establishment (Murillo-Amador 2002).…”

Estresse hídrico e salino em sementes de soja classificadas em diferentes tamanhos

“…como o Na + e o Cl - (Murillo-Amador et al 2002, Khajeh-Hosseini et al 2003. Os íons e o estresse osmótico são responsáveis tanto pela inibição quanto pela demora na germinação e estabelecimento das plântulas (Almansouri et al 2001).…”

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INTRODUÇÃOO avanço da área de cultivo de soja vem ocorrendo em todas as regiões do País (Conab 2014), especialmente no Nordeste, que possui a maior concentração de solos salinos e baixos índices pluviométricos (Cirilo et al 2010).Os solos salinizados ocorrem em condições topográficas que não favorecem uma drenagem eficiente, principalmente onde o manejo da irrigação é inadequado ou a água utilizada apresenta problemas de qualidade (Oliveira 1997).A salinidade do solo pode comprometer a germinação das sementes pela diminuição do potencial osmótico externo, impedindo a absorção de água, ou por meio dos efeitos tóxicos da absorção de íons

ABSTRACT RESUMOcomo o Na + e o Cl - (Murillo-Amador et al 2002, Khajeh-Hosseini et al 2003. Os íons e o estresse osmótico são responsáveis tanto pela inibição quanto pela demora na germinação e estabelecimento das plântulas (Almansouri et al 2001).

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Physiology of cashew plants grown under adverse conditions

“…This may be due to the reduction in water absorption during the imbibition phase or the excessive absorption of toxic ions, especially Na + and Cl - (Prisco and O'Leary, 1970), which alter metabolism by inhibiting or delaying mobilization of storage reserves and damaging the membrane system of the embryonic axis (Prisco et al, 1981;Gomes-Filho and Prisco, 1983;Chartzoulakis and Klapaki, 2000;Murillo-Amador et al, 2002).…”