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 canonical correlation is used to correlate groups of distinct variables. The objective of this study was to use canonical correlation analysis to evaluate the interaction between water quality attributes clogging-causing and the hydraulic performance of non-pressure compensating drippers operating with dilutions of aquaculture effluent in well water. The experiment was in a completely randomized design in a split-split-plot scheme with three replicates, with five dilutions in the plots (Dilution 1: 100% aquaculture effluent; Dilution 2: 75% aquaculture effluent + 25% well water; Dilution 3: 50% aquaculture effluent + 50% well water; Dilution 4: 25% aquaculture effluent + 75% well water; and Dilution 5: 100% well water), three emitters in the sub-plots (ST (1.6 L h^-1), SL (1.6 L h^-1) and NJ (1.7 L h^-1)), and three operating times in the sub-subplots (0, 80 and 160 hours, in which 0 hours operating time means the start of evaluations). The statistical analyses performed were correlation matrix and canonical analysis. The canonical correlation analysis indicated that when the concentrations of attributes increase, the hydraulic performance of the drippers decreases. The interaction of this group of attributes indicates that the clogging of drippers operating with the five dilutions of aquaculture effluent in well water occurs by the combined action of physical, chemical, and biological agents. The ST dripper was the least sensitive to the group of quality attributes of the dilutions, whereas the most sensitive was the SL dripper.

The increase in water demand in regions with limited good-quality water resources makes it necessary to study the effect of low-quality water on plant metabolism. Therefore, the objective of this study was to evaluate the effect of water and salt stress on the levels of mineral elements and accumulation of toxic elements Na⁺ and Cl⁻ in the leaves and their consequences on the production variables of the sorghum cultivar IPA SF-15. The design adopted was randomized blocks in a factorial scheme (4 × 4), with four salt concentrations (1.5; 3.0; 4.5, and 6.0 dS m⁻¹) and four irrigation depths (51.3; 70.6; 90.0, and 118.4% of crop evapotranspiration ETc) in three repetitions. To obtain nutrient, sodium, and chlorine contents in the leaf, we collected the diagnosis leaf from six plants per plot. For production data, we performed two harvests at 76 and 95 days after planting (silage point and for sucrose extraction). We evaluated the dry mass, fresh mass yield, and total dry mass for the two cutting periods and applied the F-test at the 5% significance level. There was an effect of water stress but not saline, making it possible to use saline water for sorghum irrigation. As for the toxicity of ions, the plant showed tolerance behavior to Na⁺ and Cl⁻ ions. The grain filling phase was more sensitive than the final phase of the crop cycle.

Due to its tolerance to water deficit and salinity, sorghum is considered a suitable crop for cultivation in regions affected by these stress conditions, enabling the efficient use of limited water resources. This study evaluated the resilience of the sweet sorghum cultivar BRS 506 under water deficit and salinity stress, focusing on water relations and yield performance in semiarid conditions. A randomized complete block design was employed in a 3 × 3 factorial arrangement with four replicates. Treatments consisted of three levels of irrigation water salinity (1.50, 3.75, and 6.00 dS m−1) and three irrigation levels (50%, 75%, and 100% of the estimated maximum crop evapotranspiration, ETc), corresponding to water deficits of 50%, 25%, and 0% of ETc. Salinity stress resulted in similar electrolyte leakage in both years. In 2022, relative water content decreased with increasing salinity, whereas saturation deficit and water absorption capacity increased. The highest electrolyte leakage occurred under a 25% water deficit. In contrast, water-related physiological parameters in 2021 remained stable despite water deficits. Juice yield declined by 13.38% under the highest salinity level (6.00 dS m−1) compared with the lowest (1.50 dS m−1). Under water deficit conditions, total yield, dry matter, stalk biomass, and juice yield were comparable between 0% and 25% water deficit, with significant reductions only at 50%. Overall, BRS 506 demonstrated resilience to salinity, maintaining cellular integrity. Despite adverse effects on plant water status at high salinity, total yield was unaffected. A 25% irrigation reduction resulted in only a 6.64% yield loss, indicating improved water use efficiency and highlighting the potential for sustainable cultivation of sweet sorghum in water-limited environments.

ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA PARA AMBIENTE PROTEGIDO GERTRUDES MACÁRIO DE OLIVEIRA¹; EDGO JACKSON PINTO SANTIAGO²; MÁRIO DE MIRANDA VILAS BOAS RAMOS LEITÃO³; RUY DE CARVALHO ROCHA⁴; IRIS SANTANA GONÇALVES⁵ E RODRIGO RAFAEL DA SILVA^{6   1}Departamento de Tecnologia e Ciências Sociais, Universidade do Estado da Bahia, UNEB, Juazeiro, BA, gemoliveira@uneb.br ²Programa de Pós-Graduação em Horticultura Irrigada, Universidade de Estado da Bahia, UNEB, Juazeiro, BA, edgoj@hotmail.com ³Colegiado de Engenharia Agrícola e Ambiental, Universidade Federal do Vale do São Francisco, UNIVASF, Juazeiro, BA, mario.miranda@univasf;edu.br ⁴Departamento de Tecnologia e Ciências Sociais, Universidade do Estado da Bahia, UNEB, Juazeiro, BA, rcrocha@uneb.br ⁵Departamento de Tecnologia e Ciências Sociais, Universidade do Estado da Bahia, UNEB, Juazeiro, BA, irissg@hotmail.com ⁶Departamento de Tecnologia e Ciências Sociais, Universidade do Estado da Bahia, UNEB, Juazeiro, BA, rodrigosilva_rafael@hotmail.com     1 RESUMO Tendo em vista a importância do conhecimento da evapotranspiração de referência (ETo) para estimar as diferentes demandas evapotranspiratórias, o presente trabalho teve como objetivo avaliar a ETo em ambiente protegido, comparando-a com estimativas obtidas para condições de campo aberto. O experimento foi conduzido na área experimental do DTCS-UNEB, Juazeiro, BA, no período de junho a setembro de 2015. Sob uma estrutura coberta com tela de sombreamento foi introduzida a cultura do tomate, instalado um tanque classe A (TCA) e uma estação meteorológica automática. A ETo da cobertura foi determinada a partir dos dados de evaporação do TCA instalado nesse ambiente e Kp = 1; e correlacionada com a ETo externa calculada por diferentes métodos de estimativas. A ETo da cobertura correspondeu a 77,8; 75,0 e 82,4% da ETo obtida pelos métodos de Penman-Monteith, TCA e Jensen e Haise, respectivamente; e 105 e 131,3% da ETo obtida pelos métodos de Hargreaves e Samani e Makkink, respectivamente. A evapotranspiração de referência em ambiente protegido pode ser estimada, com correlação elevada, a partir de dados externos, através do método do tanque classe A, com o Kp calculado para as condições climáticas locais.   Palavras-chave: evapotranspiração dos cultivos, tanque classe A, métodos de estimativa da ETo   OLIVEIRA, G. M.; SANTIAGO, E. J. P.; LEITÃO, M. M. V. B. R.; ROCHA, R. C.; GONÇALVES, I. S.; SILVA, R. R. REFERENCE EVAPOTRANSPIRATION ESTIMATE FOR A PROTECTED ENVIRONMENT 2 ABSTRACT   Considering how important is the knowledge on the reference evapotranspiration (ETo) to estimate the different evapotranspiration demands, this study aims to evaluate the ETo coefficient in a protected environment, comparing it with estimates obtained from the open field conditions. The experiment was conducted in the test area of DTCS-UNEB, Juazeiro, BA, from June to September, 2015. Under a structure covered with a shading screen was introduced the tomato culture, a Class A pan (TCA) and an automatic weather station. The covered area’s ETo was determined using the evaporation data from the TCA installed in this environment and the coefficient Kp = 1; and correlated with the external ETo calculated by different estimation methods. The covered area’s ETo corresponded to 77.8; 75.0 and 82.4% of the ETo obtained by the Penman-Monteith, TCA and Jensen and Haise methods, respectively; and 105 and 131.3% of the ETo obtained by the methods of Hargreaves and Samani and Makkink, respectively. The reference evapotranspiration in a protected environment can be estimated, with high correlation, from external data, using the class A pan method, with a calculated Kp for the local weather conditions.   Keywords: crop evapotranspiration, class A pan, ETo estimation methods

Considerando que o conhecimento das reais necessidades hídricas das culturas e o manejo correto da irrigação permite fornecer às plantas a quantidade ideal de água que promova o desenvolvimento adequado e a expressão de todo seu potencial produtivo, o presente trabalho teve como objetivo, determinar a evapotranspiração e os coeficientes de cultura para os diferentes estádios de desenvolvimento da melancia. A pesquisa foi conduzida de dezembro de 2014 a fevereiro de 2015 no campo experimental do DTCS/UNEB em Juazeiro. A cultivar utilizada foi a Sugar Baby. A evapotranspiração da cultura (ETc) foi obtida a partir de leituras diárias em evapotranspirômetros e a evapotranspiração de referência (ETo), obtida pelo método de Penman-Monteith. O coeficiente de cultura foi determinado pela relação Kc = ETc/ETo. Os maiores valores da ETc foram observados no estádio intermediário, atingindo valores máximos de até 10,4 mm dia^-1. A ETc média para todo o ciclo da cultura foi de 5,4 mm dia^-1. Os valores de Kc variaram de 0,51 para o estádio inicial a 1,23 para o intermediário. A demanda atmosférica foi determinante para o valor de Kc observado no estádio II, demonstrando a importância da calibração do Kc para condições climáticas específicas.