The objective of this study was to identify sorghum varieties that have growth and grain yield potential under saline conditions. The study was conducted in 2016 at a greenhouse of the Embrapa Semiárido, in Petrolina, state of Pernambuco, Brazil (9° 8’ 8.9’’ S, 40° 18’ 33.6’’ W, and altitude of 373 m). A randomized block experimental design, with a 6 × 5 factorial arrangement, and three replications was used. The treatments consisted of six grain sorghum varieties (1011-IPA, 2502-IPA, 2564-IPA, 2600-IPA, Ponta Negra, and Qualimax), and five salinity levels of the irrigation water (EC_w = 0, 1.5, 3.0, 6.0, and 12.0 dS m^-1). Plant height, stem diameter, dry matter yield, width and length of the +3 leaf, total leaf area, water use efficiency, and grain yield were evaluated. The sorghum varieties 2502-IPA and 1011-IPA presented the highest grain yields when using an EC_w of 6.0 dS m^-1, followed by Ponta Negra, Qualimax, and 2600-IPA. The 2564-IPA, 2600-IPA, and Qualimax varieties were more sensitive to the salinity effects, with reductions of 50% of the production with EC_w of 3.52, 2.75, and 4.38 dS m^-1, respectively.

Salt stress is one of the most limiting environmental factors for agricultural yields in the Semiarid region of Brazil. Considering the expansion of areas with sugarcane crops in this region, the selection of more adapted plant varieties to this environment is an essential tool for the sustainability of this activity. Thus, the objective of the present work was to evaluate the physiological and biochemical responses of plants of ten sugarcane varieties to salt stress. The experiment was conducted in a greenhouse using a randomized block design, in a 6×10 factorial arrangement consisting of six salinity levels in the irrigation water (0, 1.0, 2.0, 4.0, 6.0, and 8.0 dS m-1) and ten sugarcane varieties (VAT 90212, RB 72454, RB 867515, Q 124, RB 961003, RB 957508, SP 791011, RB 835089, RB 92579, and SP 943206), with three replications. Salt waters were applied every two days to increase the soil moisture to field capacity and promote leaching. The gas exchange, chlorophyll content, and total soluble and reducing sugars of leaves were evaluated at 90 days after planting. The highest chlorophyll contents were found in plants of the varieties Q 124, RB 96103, RB 835089, and SP 943206. The effect of salinity on the sugarcane plants affected their leaf gas exchanges and total soluble and reducing sugar contents, denoting the adaptability of plants to the stress conditions evaluated. The decrease of stomatal conductance resulted in decreases in photosynthetic rates in plants of all sugarcane varieties evaluated, except for RB 867515.

Sugarcane is one of the most affected crops by water scarcity. The efficient use of the irrigation water is an alternative to minimize this problem. The objective of this work was to evaluate biometric parameters, yield, and technological quality of sugarcane plants subjected to different controlled water deficit regimes in the sub-middle São Francisco Valley, Brazil. The experiment was conducted in a randomized block design, in two crop cycles, with three replications, with ten treatments consisted of three controlled water deficits (15%, 30%, and 45% of the crop evapotranspiration - ETc), applied at three development stages of the plant - sprouting and tillering (Stage I), grand growth (Stage II), and maturation (Stage III) - and a control with 100% of the ETc throughout the entire crop cycle. The controlled water deficit did not affect the technological quality of the sugarcane in any development stage. The sugarcane yield was higher when using a controlled water deficit of 30% of ETc in the sprouting and tillering stages of the plants. The water deficit of 15% of ETc is recommended for the grand growth, or maturation stages of the sugarcane plants for a greater water use efficiency of the production system.

O objetivo deste trabalho foi avaliar a tolerância à salinidade de seis variedades de sorgo forrageiro a partir da porcentagem de germinação e do crescimento inicial das plântulas submetidas a seis níveis de salinidade. Utilizou-se o delineamento experimental inteiramente casualizado, em esquema fatorial 6 x 6, com quatro repetições contendo 25 sementes. Os tratamentos foram seis variedades (V) de sorgo forrageiro [F305 (V1), BRS 655 (V2), BRS 610 (V3), Volumax (V4), 1.015.045 (V5), 1.016.005 (V6)] e seis níveis de salinidade [0 (água destilada); 2,5; 5,0; 7,5; 10 e 12,5 dS m-1]. O experimento foi conduzido no Laboratório de Sementes da Embrapa Semiárido, em agosto de 2012. Foram avaliados a percentagem de germinação, o comprimento da parte aérea (PA) e da raiz (R) principal, razão de comprimento PA/R, massa fresca e seca da parte aérea e do sistema radicular. Os níveis de salinidade não interferiram no processo de germinação das sementes das variedades de sorgo forrageiro até a condutividade de 10 dS m-1. Quanto ao crescimento das plântulas, os níveis de salinidade entre 3 e 5 dS m-1 favoreceram o crescimento da parte aérea e raízes demonstrando boa tolerância à salinidade das variedades de sorgo forrageiro avaliadas, principalmente de F305, Volumax e 1.015.045.

Cowpea planting season is crucial for high yield and should comprise the period of the year that warrants the best climatic conditions for cowpea cultivation. Thus, the objective of this study was to evaluate the influence of water availability and temperature on the performance of cowpea cultivars. A greenhouse experiment was conducted using a 4 × 2 × 5 factorial arrangement, with four replications. Factors included four levels of soil moisture (25, 50, 75, and 100% of water holding capacity), two growing seasons (mild and hot), and five cowpea cultivars (Carijó, Itaim, Pujante, Rouxinol, and Tapahium). The number of pods and seeds per plant, seed production, water use efficiency, shoot dry mass, root dry mass, and physiological parameters were evaluated. Seed production was higher during the mild season than during the hot season and increased linearly with increasing soil water availability. Photosynthetic activity and transpiration were higher during the hot season than during the mild season, with their reduction under a water availability of 25% regardless of the growing season. Total chlorophyll content decreased with excess water. Regardless of water availability, temperature was the most limiting climatic factor for cowpea performance. Cultivars Carijó, Itaim, and Tapahium exhibited a lower reduction in productive potential when grown in the hot season.

The objective of this work was to evaluate the biomass production and antioxidant enzymatic system activity of irrigated forage sorghum with saline aquaculture effluent under different leaching fractions. The experiment was conducted in the Caatinga Experimental Field of the Embrapa Semiarido, in Petrolina, State of Pernambuco, Brazil. The experimental design was a complete randomized block in a split-plot arrangement with four replications, consisting of three forage sorghum varieties (Volumax, F305 and Sudan) and four leaching fractions (0, 5, 10 and 15%). The vegetal materials were collected when the plants were at the soft-dough stage. The biomass production and activity of the enzymes superoxide dismutase, catalase and ascorbate peroxidase were evaluated. Irrigation with saline aquaculture effluent with leaching fraction of 15% results in low salinity level in the root zone and higher biomass production of forage sorghum Sudan and F305, in semiarid conditions. The antioxidant system was activated in the three sorghum varieties to prevent accumulation of reactive oxygen species, with the synchrony between the enzymes superoxide dismutase and catalase resulting in a better productive response of the varieties Sudan and F305.