Agriculture in semiarid regions commonly face problems because of salt and availability of irrigation water. Considering this, studies on cultures resistant to salt and water stresses involving sweet sorghum are required. Therefore, the aim was to evaluate the growth and other mechanisms of tolerance to salinity and water deficit in BRS 506 sweet sorghum. The experimental design was conducted in Upanema-RN, Brazil, in randomized blocks, where the isolated and interactive effect of 3 salinity levels, expressed as the electrical conductivity of irrigation water (1.5, 3.8, and 6.0 dS m⁻¹), and 3 irrigation depths (55, 83, and 110% of crop evapotranspiration) were evaluated. During the cycle, sorghum adapted to the salinity and deficit irrigation depth, since stem height reduced only −5.5% with increasing salinity and −11.95% with decreasing irrigation depth, and aerial dry mass was affected by interaction only at the end of the cycle. Proline, total amino acids, and total soluble sugars were not differenced by stresses. Additionally, around 68.71% of total Na⁺ was at roots at the end of the cycle. In summary, sorghum BRS 506 was more tolerant to salt than water stress and used Na⁺ compartmentalization in root cells as the main tolerance mechanism.

The aimed of this study was to evaluate the attenuating action of nitrogen doses on leaf cell membrane damage, dry biomass production and leaf area in the formation of yellow passion fruit seedlings irrigated with saline water. Treatments were arranged in a randomized block design, in split plots, corresponding to five levels of irrigation water salinity (plot) (ECw) (0.3; 1.0; 1.7; 2.4 and 3.1 dS m-1) and five doses of nitrogen fertilization (subplot) (60; 80; 100; 120 and 140% of 300 mg of N dm-3), which were repeated in five blocks. Plants were grown in pots (Citropote®) with a volume of 3,780 mL, which were filled with a mixture of soil, aged bovine manure and sawmill residue (shaving) in a ratio of 2:1:0.5, respectively. Waters with different levels of salinity were applied from 40 to 85 days after sowing, when the plants were in transplanting conditions. At 85 days after sowing, the percentage of cell damage based on electrolyte leakage, variables of dry biomass, leaf area and specific leaf area were evaluated. Increment in irrigation water salinity reduces the biomass accumulation of yellow passion fruit seedlings; The increase in nitrogen dose did not mitigate the effect of salinity, which reduced cell membrane integrity, making the plant more sensitive.

HIGHLIGHTS Electrical conductivity of water of 3.0 dS m-1 reduces the chlorophyll synthesis and production of custard-apple. NPK recommendation of 100-125-125, 125-125-100 and 125-125-125% cause more damage to the cell membrane. Reduction in the quantum efficiency of custard-apple under salt stress is indicative of photoinhi-bitory damage.

The study aimed to evaluate the mitigating effect of nitrogen (N) on the damages caused by irrigation water salinity, in the production of yellow passion fruit seedlings. A randomized block design in split plots was used, with five levels of irrigation water salinity (plot) (0.3, 1.0, 1.7, 2.4 and 3.1 dS m^-1) and five doses of N fertilization (sub-plot) (180, 240, 300, 360 and 420 mg of N dm^-3), with five replicates, totaling 125 experimental units, with one plant per plot. The seedlings were produced in 3.780 mL tubes, used as drainage lysimeter, which received a daily irrigation depth based on water balance. Growth and contents of chlorophyll and carotenoids were evaluated at 85 days after sowing. The increase in irrigation water salinity reduced stem diameter, plant height, number of leaves, chlorophyll a, chlorophyll b and total chlorophyll; increasing N doses also led to linear decline in stem diameter and plant height. Application of increasing doses of N did not attenuate the effect of salinity on growth and pigment contents.

Salt stress results in physiological changes that inhibit plant growth and development. Ca-complex sources are used as a potential salt stress attenuator. This study was carried out with the aim of verifying the effects of Ca-complex sources in reducing the effects of saline water stress on the physiological aspects of sour passion fruit seedlings. The experiment was carried out in a randomized block design with a 2 × 2 × 3 factorial scheme, consisting of two cultivars of sour passion fruit (BRS GA1 and BRS SC1), two levels of water salinity (electrical conductivity of 0.5 and 4.0 dS m⁻¹) and three sources of Ca-complex (without, organic acids and amino acids). The traits measured at 60 days after sowing were gas exchange, chlorophyll indices, chlorophyll fluorescence, electrolyte leakage, and relative water content in the leaf limb. Under moderate water salinity, the application of Ca-complex in amino acids promoted increases of 49.84% and 43.71%, respectively, in the efficiency of water use and carboxylation. The application of complex sources increased the stability of cell membranes, reducing electrolyte leakage, providing higher relative water content in seedlings irrigated with moderately saline water. From the results, we conclude that Ca-complex sources have potential as modulators of moderately saline water stress in sour passion fruit seedlings.

A região semiárida brasileira caracteriza-se por apresentar baixa disponibilidade hídrica devido a persistentes períodos de seca, com isso há necessidade de melhor uso da água na irrigação das culturas. Assim, objetivou-se avaliar o efeito do déficit hidrico, imposto nas distintas fases fenológicas, sobre a produtividade de algodão em pluma, a percentagem e a qualidade das fibras das cultivares BRS 286 e BRS 336 de algodoeiro herbáceo. O delineamento experimental foi blocos casualizados em parcelas subdivididas, com os seis regimes de déficits hídricos, aplicados em diferentes fases fenológicas do algodoeiro, formando as parcelas e, as duas cultivares de algodoeiro herbáceo, as subparcelas, em 4 repetições. As variáveis analisadas foram rendimento e percentagem de algodão em pluma e algumas características tecnológicas da fibra, as quais foram Comprimento, Uniformidade, Índice de fibras curtas, Resistência, Alongamento à ruptura, Índice micronaire e Maturidade. O déficit hídrico foi mais relevante nas fases de botão, flor e maça. As fases mais tolerantes ao déficit foram crescimento inicial e capulho. As características tecnológicas das fibras como comprimento, uniformidade, índice micronaire e maturidade, inerentes a cada cultivar, se apresentaram dentro do padrão varietal requerido pela indústria têxtil. As duas cultivares mostraram bom potencial de cultivo para o semiárido, considerando as características distintas, mas a escolha é de acordo com o interesse do produtor.