Salicylic Acid as a Salt Stress Mitigator on Chlorophyll Fluorescence, Photosynthetic Pigments, and Growth of Precocious-Dwarf Cashew in the Post-Grafting Phase.

Salicylic acid is a phytohormone that has been used to mitigate the effects of saline stress on plants. In this context, the objective was to evaluate the effect of salicylic acid as a salt stress attenuator on the physiology and growth of precocious-dwarf cashew plants in the post-grafting phase. The study was carried out in a plant nursery using a randomized block design in a 5 × 4 factorial arrangement corresponding to five electrical conductivity levels of irrigation water (0.4, 1.2, 2.0, 2.8, and 3.6 dS m-1) and four salicylic acid concentrations (0, 1.0, 2.0, and 3.0 mM), with three replications. Irrigation water with electrical conductivity levels above 0.4 dS m-1 negatively affected the relative water content in the leaf blade, photosynthetic pigments, the fluorescence of chlorophyll a, and plant growth and increased electrolyte leakage in the leaf blade of precocious-dwarf cashew plants in the absence of salicylic acid. It was verified through the regression analysis that salicylic acid at a concentration of 1.1 mM attenuated the effects of salt stress on the relative water content and electrolyte leakage in the leaf blade, while the concentration of 1.7 mM increased the synthesis of photosynthetic pigments in precocious-dwarf cashew plants.

Production and Fiber Characteristics of Colored Cotton Cultivares under Salt Stress and H2O2.

Salt stress reduces the yield and quality of colored fiber cotton production, but this problem can be mitigated by the foliar application of hydrogen peroxide in adequate concentrations. In this context, the objective of the present study was to evaluate the production and characteristics of fibers of naturally colored cotton cultivares under irrigation with low- and high-salinity water and leaf application of hydrogen peroxide. The experiment was carried out in a greenhouse under a randomized block design, arranged in 4 × 3 × 2 factorial scheme, corresponding to four concentrations of hydrogen peroxide (0, 25, 50, and 75 µM), three cultivares of colored fiber cotton ('BRS Rubi', 'BRS Topázio', and 'BRS Verde'), and two electrical conductivities of water (0.8 and 5.3 dS m-1), with three replicates and one plant per plot. Irrigation with water of 0.8 dS m-1 associated with a foliar application of 75 µM of hydrogen peroxide favored the lint and seed weight, strength, micronaire index, and maturity of 'BRS Topázio'. The 'BRS Rubi' cotton cultivar showed higher tolerance to salinity, followed by the 'BRS Topázio' and 'BRS Verde' cultivares regarding the yield of seed cotton weight, with reduction below 20% under water of 5.3 dS m-1.

NPK Accumulation, Physiology, and Production of Sour Passion Fruit under Salt Stress Irrigated with Brackish Water in the Phenological Stages and K Fertilization.

This research aimed to evaluate the effects of salt stress, varying the phenological stages, and K fertilization on NPK concentrations, physiology, and production of Passiflora edulis Sims. The research was carried out at the University Farm of São Domingos, Paraíba, Brazil, using a randomized block design with a 6 × 2 factorial arrangement. Six irrigation strategies were evaluated (use of low electrical conductivity water (0.3 dS m-1) during all stages of development and application of high-salinity water (4.0 dS m-1) in the following stages: vegetative, flowering, fruiting, successively in the vegetative/flowering, and vegetative/fruiting stages) and two potassium levels (207 and 345 g K2O per plant), with four replications and three plants per plot. The leaf concentrations of N, P, and K in the sour passion fruit plants found in the present study were below the optimal levels reported in the literature, regardless of the development stage and the cultivation cycle. The relative water content, stomatal conductance, and photosynthesis were reduced by salt stress in the first cycle. However, in the second cycle, irrigation with 4.0 dS m-1 in the vegetative/flowering stages increased the CO2 assimilation rate. Passion fruit is sensitive to salt stress in the vegetative/flowering stages of the first cycle. In the second cycle, salt stress in the fruiting stage resulted in higher production per plant.

Production components of crambe in paraiba semi-arid region with nitrogen fertilization and different spacings / Componentes de produção de crambe no semiárido paraibano com adubação nitrogenada e diferentes espaçamentos

Crambe (Crambe abyssinica H.), a promising species in the production of biodiesel, has low planting cost, high oil content and easy extraction, besides being an alternative for the crop rotation system. The objective of this study was to evaluate the effects of nitrogen fertilization and line spacing on the production components and yield of the crambe crop under semi-arid conditions. The study was conducted under field conditions in the experimental area of the National Semi-Arid Institute-INSA, located in the city of Campina Grande-PB. The experimental design was a randomized complete block design in 4 x 2 factorial scheme, consisting of four nitrogen doses (30, 60, 90, 120 kg ha-1) with two spacings between planting lines (0.20 and 0.40 meters) with three replications, totaling 24 experimental plots. The evaluated parameters were: number of siliques per plant, dry weight of shoots, number of branches (primary and secondary), primary stem length, number of siliques per stem, mass of 1000 grains and productivity. The data were submitted to analysis of variance, in which the nitrogen doses (quantitative factor) were compared by regression analysis. The different spacings were compared by means of a t-test at the 0.05 probability level by using statistical software SISVAR version 5.2. Nitrogen fertilization at 0.40 m spacing between the planting lines led to the best results for the production components, and the highest productivity was obtained at 0.20 m spacing of with nitrogen fertilization of 120 kg ha-1.

O crambe (Crambeabyssinica H.), espécie promissora na produção de biodiesel, apresenta baixo custo de plantio, elevado teor de óleo e de fácil extração, além de ser alternativa para o sistema de rotação de culturas. Mediante a necessidade de conhecimento para ampliação do cultivo dessa espécie, este estudo teve como objetivo avaliar os efeitos da adubação nitrogenada e espaçamento entre linhas no cultivo nos componentes de produção e na produtividade da cultura do crambe em condições semiáridas. O estudo foi conduzido em condições de campo na área experimental pertencente ao Instituto Nacional do Semiárido-INSA, situado no município de Campina Grande-PB. O delineamento experimental utilizado foi em blocos casualizados, no esquema fatorial 4 x 2, sendo constituído de quatro doses de nitrogênio (30; 60; 90; 120 kg ha-1) com dois espaçamentos entre linhas de plantio (0,20 e 0,40 metros) e com três repetições, totalizando 24 parcelas experimentais. Os parâmetros avaliados foram: número de síliquas por planta, massa seca da parte aérea, número de ramificações (primárias e secundárias), comprimento de haste primária, número de silíquas por haste, massa de 1000 grãos e produtividade. Os dados obtidos foram submetidos à análise de variância, em que as doses de nitrogênio (fator quantitativo) foram comparadas por análise de regressão. Os diferentes espaçamentos foram comparados por meio de comparação de médias, pelo teste t, ao nível de 0,05 de probabilidade utilizando-se software estatístico SISVAR versão 5.2. A adubação nitrogenada sob espaçamento de 0,40 m, entre as linhas de plantio, proporcionou os melhores resultados quanto aos componentes de produção, e a maior produtividade foi obtida no espaçamento referente a 0,20 m com a adubação nitrogenada de 120 kg ha-1.