To evaluate the interaction between foliar application of salicylic acid and Bradyrhizobium inoculation on the morphophysiology of cowpea under water stress conditions, four genotypes (BRS Rouxinol, BRS Marataoã, BRS Aracê and BR 17 Gurguéia) were subjected to five combinations of water availability: 100% replacement of crop evapotranspiration (control); 50% replacement of crop evapotranspiration (water stress); water stress + salicylic acid; water stress + Bradyrhizobium inoculation; and water stress + salicylic acid + Bradyrhizobium inoculation. The experiment was set up in a 4 × 5 factorial randomized block design, with four replicates and four plants per plot. Water stress negatively affected the leaf water potential, growth, proline contents and antioxidant activity of the cowpea genotypes, and BRS Marataoã was the most sensitive. Under water stress conditions, Bradyrhizobium inoculation was efficient for BRS Rouxinol, but was only efficient for BRS Marataoã, BRS Aracê and BR 17 Gurguéia when associated with foliar application of salicylic acid, maintaining their values of leaf water potential, growth, proline content and activities of superoxide dismutase, ascorbate peroxidase, and catalase similar to those of the control treatment.

Silicon and proline play important physiological, metabolic and functional roles in plants, especially under water deficit conditions. Their application can mitigate the adverse effects of stress in crops by increasing water use efficiency and antioxidant activity. The objective of this study was to evaluate silicon (Si) as attenuator of the effects of water deficit on cowpea cultivars, through physiological, biochemical and growth indicators. The experimental design was randomized blocks with four cultivars (BRS Guariba, BRS Itaim, BRS Aracê and BRS Rouxinol) and four irrigation treatments associated or not with Si application (W100 - 100% ETo; W50 - 50% ETo; W50+100Si and W50+200Si, with 100 and 200 mg L-1 silicon, respectively), in a 4 x 4 factorial scheme, with five replicates. Leaf water potential, proline concentration, antioxidant enzymes and growth indicators were evaluated in cowpea plants. Under water deficit conditions, all cultivars showed reductions in leaf water potentials, which compromised plant growth. However, Si applications of 200 mg L-1 in the cultivar BRS Guariba and 100 and 200 mg L-1 in the cultivar BRS Itaim minimized the effects of stress, by increasing leaf water potential and the activity of the enzyme ascorbate peroxidase, in both cultivars, besides increasing proline concentration in the former and reducing proline concentration in the latter, which ensured the maintenance of growth. Despite the no contribution to the increase in water potential, Si applications of 100 and 200 mg L-1 in BRS Rouxinol and BRS Aracê, respectively, reduced the deleterious effects of the stress on their growth by regulating the enzymatic metabolism and proline.

A B S T R A C TSesame is an important crop in Northeast Brazil, where climate conditions require adapted genotypes and alternatives for plant defense against drought. This study aimed to evaluate the salicylic acid as drought attenuator in sesame genotypes. The experiment evaluated six genotypes (BRS Seda, CNPA-G2, CNPA-G3, CNPA-G4, LAG-Branquinha and LAGPretinha), five osmotic potentials (0, -0.2, -0.4, -0.6 and -0.8 MPa) and three seed treatments (soaking in distilled water, in salicylic acid and no treatment). CNPA-G4 is tolerant to drought in the germination stage. Salicylic acid at 10 -5 M induced tolerance to drought stress in sesame, but it is necessary to test other concentrations.Ácido salicílico como atenuador de estresse hídrico na germinação e no desenvolvimento inicial de gergelim R E S U M O O gergelim é uma importante cultura no Nordeste brasileiro, cujas condições de semiaridez exigem genótipos adaptados, além de alternativas para defesa da planta contra a seca. Assim, objetivou-se avaliar o ácido salicílico como atenuador do estresse hídrico em genótipos de gergelim. Foram estudados seis genótipos (BRS Seda, CNPA-G2, CNPA-G3, CNPA-G4, LAG-Branquinha e LAG-Pretinha); cinco potenciais osmóticos (0; -0,2; -0,4; -0,6 e -0,8 MPa) e três tratamentos das sementes (pré-embebição em água destilada; em ácido salicílico e sem embebição). O genótipo CNPA-G4 possui elevada capacidade de tolerância ao déficit hídrico, na fase de germinação. O ácido salicílico a 10 -5 M induziu tolerância ao estresse hídrico em gergelim, porém se necessita testar outras concentrações.

The aim of this study was to evaluate the changes in osmoregulatory metabolism of cotton genotypes subjected to water deficit and recovery period. In a greenhouse, six cotton genotypes and two water managements were combined in a 6 x 2 factorial scheme, in a completely randomized design, evaluated after 14 and 22 days under water stress and recovery conditions, respectively. The water status, growth indicators and compatible solutes in the leaves were evaluated. The genotypes BRS Seridó, BRS Aroeira and BRS 7MH withstand better the stress condition because they had lower variations in their water potentials due to the osmotic adjustment and maintained their growth under water deficit conditions. The BRS 286 is the most sensitive genotype to the water deficit condition, since it showed greater variations in its water potential, which ultimately stopped its growth. Water replacement during the recovery period allowed growth resumption in most of the genotypes, mainly CNPA 5M and BRS 286. After the recovery period, variations in the concentrations of osmoregulators indicate the plasticity of cotton in regulating the concentrations of osmoregulators under favorable and unfavorable water conditions. Mudanças no metabolismo osmorregulador de genótipos de algodoeiro durante déficit hídrico e período de recuperação RESUMO: O objetivo do presente estudo foi avaliar as mudanças no metabolismo osmorregulador de genótipos de algodoeiro submetidos ao déficit hídrico e ao período de recuperação. Em casa de vegetação, seis genótipos de algodoeiro e dois manejos hídricos foram combinados em esquema fatorial 6 x 2, em delineamento inteiramente casualizado, avaliados após 14 e 22 dias em condições de estresse hídrico e recuperação, respectivamente. Foram avaliados o status hídrico, indicadores de crescimento e solutos compatíveis em folhas. Os genótipos BRS Seridó, BRS Aroeira e BRS 7MH suportam melhor a condição de estresse por apresentarem menores variações nos seus potenciais hídricos devido ao ajustamento osmótico e por manterem seu crescimento em condições de deficit hídrico. O BRS 286 é o genótipo mais sensível à condição de deficit hídrico, pois apresentou maiores variações no seu potencial hídrico que repercutiu na paralização do seu crescimento. A reposição hídrica durante o período de recuperação permitiu a retomada do crescimento da maioria dos genótipos, principalmente CNPA 5M e BRS 286. Após o período de recuperação hídrica, as variações nas concentrações dos osmorreguladores indicam plasticidade do algodoeiro em regular os níveis de osmorreguladores em condições favoráveis e desfavoráveis de água.Palavras-chave: Gossypium hirsutum L., ajustamento osmótico, osmólitos compatíveis, seca

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