Deficit irrigation is applied to several agricultural crops as a water-saving irrigation strategy. The tomato plant is sensitive to water stress; however, integration with biostimulant applications, based on seaweed extracts, could be a strategy for plants adapting to this abiotic condition. The objective of this study was to evaluate agronomic and quality aspects of tomato cultivated under deficit irrigation combined with Ascophyllum nodosum extract (ANE) application. The experiment was conducted using a completely randomized design with two water replacement levels, 70 and 100% of crop evapotranspiration (ETc), and five doses of ANE (0, 0.1, 0.2, 0.3 and 0.4%) applied via soil drench. The interaction between ANE and ETc was significant (p < 0.05) in terms of plant growth, physiological parameters, fruit yield, yield components and fruit quality. Results indicated that when the tomato plant is under deficit irrigation, a higher ANE dose is required to achieve better development when compared to the 100% ETc condition, where the dose is lower. Under deficit irrigation, the largest fruit yield was obtained with 0.3 and 0.4% ANE, and with 100% ETc, the largest fruit yield was obtained with 0.2% ANE. ANE applications were also effective in increasing plant height, stem diameter, plant biomass, leaf area, chlorophyll and relative water content. In addition, tomato quality was also favored under deficit irrigation and seaweed extract application. We conclude that ANE applications attenuate water deficit effects in tomato plants and provide a strategy to ameliorate tomato yield, tomato quality and water use in agriculture.

In regions where water is a limited resource, lettuce production can be challenging. To address this, water management strategies like deficit irrigation are used to improve water-use efficiency in agriculture. Associating this strategy with silicon (Si) application could help maintain adequate levels of agricultural production even with limited water availability. Two lettuce crop cycles were conducted in a completely randomized design, with a factorial scheme (2 × 3), with three irrigation levels (60%, 80% and 100%) of crop evapotranspiration (ETc), and with and without Si application. To explore their combined effects, morphological, productive, physiological and nutritional parameters were evaluated in the crops. The results showed that deficit irrigation and Si application had a positive interaction: lettuce yield of the treatment with 80% ETc + Si was statistically similar to 100% ETc without Si in the first cycle, and the treatment with 60% ETc + Si was similar to 100% ETc without Si in the second cycle. Photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, transpiration rate and total chlorophyll content increased under water-stress conditions with Si application; in the first cycle, the treatment with 80% ETc + Si increased by 30.1%, 31.3%, 7.8%, 28.46% and 50.3% compared to the same treatment without Si, respectively. Si application in conditions of water deficit was also beneficial to obtain a cooler canopy temperature and leaves with higher relative water content. In conclusion, we found that Si applications attenuate water deficit effects and provide a strategy to ameliorate the yield and water productivity in lettuce crops, contributing to more sustainable practices in agriculture.

Seaweed extracts have several functions in agriculture due to their composition that is rich in nutrients, plant hormones, and bioactive substances. It is a natural product used as a biostimulant especially to promote the growth and development of plants and their tolerance to environmental stresses. The objective of this study was to analyze the response to a biostimulant containing seaweed extract derived from Ascophyllum nodosum in the cultivation of tomato and eggplant seedlings, analyzing the growth and physiological parameters in two different regions of Brazil. Cherry tomato and eggplant were cultivated in polyethylene trays for 30 days. In each crop, five treatments were tested, comparing the use of a commercial seaweed extract in application doses and forms, which were the control (without seaweed application); 0.1%, 0.2%, and 0.3% of the seaweed extract applied by irrigation water; and treatment with 0.2% of the seaweed extract by foliar application. This study confirms the efficacy of incorporating seaweed extract from Ascophyllum nodosum as a bio-input into the production phase of Solanaceae seedlings. The seedlings which received the seaweed extract significantly increased some morphological parameters, mainly regarding the biomass and length of leaves, stems, and roots. In general, applying both methods through irrigation water and foliar application were effective in providing benefits compared to the control treatment. The intermediate dose (0.2%) was the most effective in promoting improvement in the analyzed parameters. This underscores the importance of obtaining quality seedlings for subsequent planting in the field, potentially leading to better acclimatization and initial adaptation.

Water deficit in cauliflower cultivation may impair its development and yield. This study aimed to analyze the agronomic performance of cauliflower grown in a protected environment, under different water conditions and silicon (Si) doses. The experiment was arranged in a randomized block design, in a 3 x 4 factorial scheme, with three levels of water replacement [40, 70 and 100 % of the evapotranspiration (ETc)] and four Si doses (0, 50, 100 and 150 kg ha-1), with four replications. Leaf (SPAD index, area, fresh and dry weight), stem (diameter, height, fresh and dry weight) and inflorescence (diameter, fresh weight, dry weight, water content and commercial classification) characteristics were evaluated. The replacement of 40 % of the ETc showed lower results for the SPAD index in the phases II and III, leaf area, leaf and stem fresh weight and inflorescence diameter. The 70 % replacement cultivation showed a yield similar to that of the 100 % of the ETc. The use of Si was beneficial for the productive performance of the cauliflower at all levels of water replacement.

The objective of this work was to determine the accumulation of silicon in the plant components of cauliflower (Brassica oleracea var. botrytis) grown with different levels of water replacement and rates of Si. The experimental design was a randomized complete block with three water replacement conditions (40, 70, and 100% evapotranspiration), four Si rates (0, 50, 100, and 150 kg ha-1), and four replicates. Daily evapotranspiration was determined with constant water table lysimeters, with water replacement by a drip system. As a source of Si, silicon oxide was applied three times in the crop cycle - at the initial, intermediate, and final development stages of the plant. At the end of the cycle, samples of plant tissue (root, stem, leaves, and inflorescence) and soil were collected to determine Si by spectrometry. The Si content in the soil was not influenced by water replacement, only by silicate fertilization. The silicon applied to the soil increased the content of the element in the plant components, especially in the roots. Water replacement influences the accumulation of Si in cauliflower plant tissues, with lower amounts of the element under water deficit conditions.