Knowledge about the effect of chemical conditioners on the reduction of the deleterious effects caused by salinity on crops is of great importance for the expansion of the cultivation of vegetable crops such as zucchini in the semi-arid region of the Northeast. In this context, the objective of the present study was to evaluate the effect of the foliar application of hydrogen peroxide as a mitigator of salt stress on the gas exchange, production, and postharvest fruit quality of zucchini cultivated in a hydroponic system. The study was conducted in NFT-type (Nutrient Film Technique) hydroponic system in a greenhouse, in Pombal — PB, Brazil. The experimental design was completely randomized, in a 4 × 4 factorial scheme, corresponding to four levels of electrical conductivity of the nutrient solution - ECns (2.1 (control); 3.6; 5.1 and 6.6 dS m−1), and four concentrations of hydrogen peroxide - H2O2 (0; 20; 40 and 60 μM), with three replicates. Nutrient solution with electrical conductivity above 2.1 dS m−1 caused a reduction in gas exchange and the total number of fruits of zucchini. An increase in nutrient solution salinity levels increased the total soluble solids content of the fruits and the initial fluorescence of zucchini. Under conditions of nutrient solution salinity above 2.1 dS m−1, hydrogen peroxide could not mitigate the effects of salt stress. Application of 20 μM of H2O2 when the plants were grown in a nutrient solution of 2.1 dS m−1 promoted higher total fruit weight and basal diameter of the fruits.

The objective of this study was to evaluate the gas exchange, growth and production of yellow passion fruit cv. BRS GA1, as a function of irrigation management strategies with saline water and potassium doses. The experiment was conducted under field conditions in São Domingos, PB, Brazil. A randomized block design was used in a 6 * 2 factorial scheme. The treatments consisted of six strategies of irrigation with saline waters (irrigation with low-salinity water throughout the crop cycle - SE; irrigation with high-salinity water in the vegetative stage - VE; flowering stage - FL; fruiting stage - FR; in the successive vegetative/flowering stages - VE/FL; vegetative/fruiting stages - VE/FR) and two doses of potassium (100 and 130% of the K2O recommendation), with four replicates and four plants per plot. The 100% dose corresponded to 60 g of K 2O plant-1 year-1. The effects of using high-salinity water (3.2 dS m-1) alternated with low-salinity water (1.3 dS m-1) were evaluated in different stages of the cultivation cycle. Irrigation with saline water in the fruiting stage promoted an increase in intercellular CO2 concentration and decrease in CO2 assimilation, with effects of non-stomatal origin standing out as limiting factors of photosynthetic efficiency. The highest CO 2 assimilation rate in plants subjected to water salinity of 1.3 dS m-1 throughout the cycle resulted in increments in the number of fruits and in the production per plant of the passion fruit cv. BRS GA1.

Os solos das regiões áridas e semiáridas podem naturalmente conter sódio trocável em teores suficientes para reduzir significativamente o desenvolvimento e a produtividade das culturas; entretanto, diversos métodos podem ser empregados na recuperação destes solos, sendo a aplicação de melhoradores químicos e material orgânico associado ao emprego de espécies vegetais tolerantes, o meio mais efetivo para amenizar este problema. Neste sentido, objetivou-se com esta pesquisa avaliar a tolerância do algodoeiro de fibra colorida, cv. BRS Topázio, cultivado em solos com distintos percentuais de sódio trocável (PST) e doses de matéria orgânica em experimento conduzido em condição de casa de vegetação do CCTA/UFCG. O delineamento estatístico utilizado foi o de blocos ao acaso, testando-se cinco níveis de PST(13,6; 22,4; 30,1; 39,0 e 48,0%) e quatro doses de matéria orgânica (0; 5; 10 e 15%, base volume), em esquema fatorial 5 x 4, com três repetições. O algodoeiro colorido cv. BRS Topázio é tolerante ao sódio trocável, podendo ser cultivado em solo com PST de até 30%. Nível de esterco bovino de 10% atenuou o efeito do sódio trocável sobre a área foliar, fitomassa seca da parte aérea e massa de semente do algodoeiro respectivamente, sob PST de 31, 48 e 48. O diâmetro de caule, a altura de planta e a massa de pluma de algodoeiro tiveram incremento até o nível de esterco de 15%, já o maior índice de fiabilidade foi obtido sob 9% de esterco.

The study was conducted to evaluate the growth and physicochemical quality of West Indian cherry cv. BRS 366-Jaburu, as a function of saline water irrigation and potassium fertilization. The research was conducted under greenhouse conditions in Campina Grande-PB. The experimental design was randomized blocks in a 2 x 4 factorial arrangement, which consisted of two levels of irrigation water electrical conductivity - ECw (0.8 and 3.8 dS m-1) and four levels of potassium of 50, 75, 100 and 125% of the recommendation, in which the dose of 100% was equivalent to 19.8 g of K2O per plant year-1, with three replicates and one plant per replicate. Water salinity of 3.8 dS m-1 inhibited the absolute and relative growth in diameter of the rootstock and scion of West Indian cherry plants, in the period from 100 to 465 days after transplanting. The interaction between saline levels and potassium doses was significant for hydrogen potential, soluble solids and anthocyanins levels in BRS 366-Jaburu West Indian cherry fruits, with the highest values obtained in plants fertilized with 125, 125 and 50% of the K2O recommendation and under water salinity of 3.8, 3.8 and 0.8 dS m-\ respectively. Increasing doses of K did not attenuate the effects of salt stress on the relative growth in rootstock stem diameter, fruit polar diameter and anthocyanin contents of West Indian cherry. Soluble solid contents in West Indian cherry pulp increased with application of K2O.

<p>Além de favorecer o desenvolvimento e a produção das culturas, a adubação tem sido considerada uma técnica capaz de reduzir o efeito da salinidade nas plantas. Neste sentido, desenvolveu-se o trabalho<strong> </strong>para avaliar a influência de doses de nitrogênio na formação de mudas de goiabeira cv. Paluma irrigadas com águas de diferentes salinidades. O experimento foi desenvolvido em casa de vegetação do Centro de Ciências e Tecnologia Agroalimetar da UFCG, Pombal, PB com delineamento experimental em blocos casualizados, em esquema fatorial 5 x 4, sendo os tratamentos correspondentes aos níveis de condutividade elétrica da água (CEa) de 0,3; 1,1; 1,9; 2,7 e 3,5 dS m^-1 associados a 70, 100, 130 e 160% da dose recomendada de nitrogênio (N) para mudas de goiabeira cv. Paluma, com quatro repetições, e cinco plantas por unidade experimental. Aos 180 dias após a emergência, a adubação nitrogenada na dose de 773 mg de N dm^-3 reduz o efeito da salinidade da água de irrigação sobre o diâmetro do caule das mudas. As plantas adubadas com as doses variando de 541 a 618,4 mg de N dm^-3 atingem maior crescimento em altura de planta, número de folhas e área foliar. A área foliar e a massa seca total de mudas de goiabeira atingem maiores valores no nível de CEa de 1,3 dS m^-1.</p><p align="center"><strong>Effect of nitrogen fertilization in the formation of guava seedlings irrigated with salted water</strong></p><p><strong>Abstract</strong><strong>: </strong>In addition to favoring the development and production of crops, the fertilizer has been considered a technique capable to reduce the effect of salinity on plants. The experiment was conducted in a greenhouse of the ‘Centro de Ciências e Tecnologia Agroalimentar’ of UFCG, Pombal, PB in a randomized block design a 5 x 4 factorial, with the treatments corresponding to the electrical conductivity of irrigation water (ECw) 0.3; 1.1; 1.9; 2.7 and 3.5 dS m^-1 associated with doses of 70, 100, 130 and 160% of recommended nitrogen (N) for guava seedlings Paluma,  with four replications, using five plants per experimental unit. At 180 days after emergence, the nitrogen fertilization at a dose of 773 mg N dm^-3 reduces the effect of irrigation water salinity on the stem diameter of seedlings. The plants fertilized with doses ranging from 541 at 618.4 mg of the N dm^-3 reach higher growth in plant height, leaf number and leaf area. The leaf area and total dry mass of guava seedlings reach higher values at the ECw level of 1.3 dS m^-1.</p>