Radish plants do not tolerate lower fertile soils (^{Basha & El-Aila, 2015}). ^{Cecilio Filho et al. (1998}) reported that radish is not demanding about soil type, but it needs to have a great deal of humus. Therefore, organic fertilizer must be incorporated into the soil to allow a good development of the root (^{Filgueira, 2008}; ^{Kumat et al., 2014}). According to Trani & ^{Raij (1997}), 30-50 t ha^-1 should be applied of well-aged cattle manure or organic compost, being necessary the largest dose for sandy soils.

The current study aimed to evaluate the effect of split application of potassium (K) fertilizer on the production and quality of sweet potatoes. Ten treatments were evaluated in factorial design (3 × 3 + 1): three doses of potassium (60, 90, and 120 kg K₂O ha⁻¹); three application types (100% applied at planting; 50% applied at planting and 50% was given as topdressing; 25% applied at planting and 75% was given as topdressing) and one control (without the application of K₂O either at planting or topdressing). The experiment used a randomized complete block design and four repetitions. The following parameters were studied: root number; root fresh matter per plant; total dry matter; yield; total macronutrient extraction; sugar content of starch; and commercial starch. The production characteristics of the roots presented a significant interaction between the factors doses of potassium and application types (parcelaments). Finally, better results were obtained when potassium was applied 50% at planting and 50% as topdressing.

The literature has confirmed the efficacy of sulphur (S) when growing Brassicaceae. However, there are no studies with this nutrient on broccoli. Therefore, the aim of this study was to evaluate the response of broccoli (hybrid Avenger) to sulphur rates applied at top dressing in the presence or absence of organic compost at planting. The experimental design was a randomized complete block, with ten treatments (5 x 2 factorial design) and four repetitions. Treatments consisted of five S (ammonium sulphate) rates (0, 31, 62, 93 and 124 kg ha-1); with organic compost (100 t ha-1) in planting or without organic compost in planting. After harvesting, head fresh matter, head diameter and number of leaves were evaluated. In general, head diameter, head height and fresh matter increased in all treatments by adding organic compost. A quadratic effect was observed for head fresh matter and head height by applying organic compost (100 tha-1), as the maximum values were 620.6 g and 17.2cm at the rate of 66.9 and 49.2 kg S ha-1, respectively. Key words: Brassica oleracea var. italica, fertilization, sulphate.

The current study aimed to evaluate the effect of top-dressed potassium (K) application on the production of hybrid cucumber “Sapphire.” The experimental design was a randomized complete block, with five blocks of 0.80 × 0.40 m² each and eight replicate plants per block. The five fertilization rates of K used were 0, 45, 90, 135, and 180 kg K₂O ha⁻¹. Data collection consisted of the estimation of fruit diameter, fruits length, fruit fresh and dry weights, the number of fruits per plant, and the weight of fruits per plant. The number of fruits per hectare and the fruit fresh weight per hectare were calculated. Fruit tissue was analyzed for determination of macronutrient concentrations, pH, titratable acidity, soluble solids, sugar contents, and protein content. The data were statistically analyzed using regression analysis and analysis of variance (ANOVA). There was a significant effect of the fertilization rate of K on fruit diameter, fruit fresh and dry weights, macronutrients concentrations in fruits, titratable acidity, soluble solids, and reducing sugars. A quadratic equation was adjusted for the number of fruits per plant and per hectare; fruit yield per plant and per hectare, with maximum top-dressing doses, was estimated to be between 60 and 95 kg K₂O ha⁻¹. A linear increase was obtained in the pH. An increase in the K fertilization rate caused a linear decrease in the fruit length.

Capsicum annuum L. has worldwide distribution, but drought has limited its production. There is a lack of research to better understand how this species copes with drought stress, whether it is reversible, and the effects of mitigating agents such as salicylic acid (SA). Therefore, this study aimed to understand the mechanisms of action of SA and rehydration on the physiology of pepper plants grown under drought conditions. The factorial scheme adopted was 3 × 4, with three water regimes (irrigation, drought, and rehydration) and four SA concentrations, namely: 0 (control), 0.5, 1, and 1.5 mM. This study evaluated leaf water percentage, water potential of shoots, chlorophylls (a and b), carotenoids, stomatal conductance, chlorophyll a fluorescence, and hydrogen peroxide (H₂O₂) concentration at different times of day, water conditions (irrigation, drought, and rehydration), and SA applications (without the addition of a regulator (0) and with the addition of SA at concentrations equal to 0.5, 1, and 1.5 mM). In general, exogenous SA application increased stomatal conductance (gs) responses and modified the fluorescence parameters (ΦPSII, qP, ETR, NPQ, D, and E) of sweet pepper plants subjected to drought followed by rehydration. It was found that the use of SA, especially at concentrations of 1 mM in combination with rehydration, modulates gs, which is reflected in a higher electron transport rate. This, along with the production of photosynthetic pigments, suggests that H₂O₂ did not cause membrane damage, thereby mitigating the water deficit in pepper plants. Plants under drought conditions and rehydration with foliar SA application at concentrations of 1 mM demonstrated protection against damage resulting from water stress. Focusing on sustainable productivity, foliar SA application of 1 mM could be recommended as a technique to overcome the adverse effects of water stress on pepper plants cultivated in arid and semi-arid regions.