Agriculture in the current century is seeking sustainable tools in order to generate plant production systems with minimal negative environmental impact. In recent years it has been shown that the use of insect frass is an option to be used for this purpose. The present work studied the effect of low doses (0.1, 0.5, and 1.0% w/w) of cricket frass (Acheta domesticus) in the substrate during the cultivation of tomatos under greenhouse conditions. Plant performance and antioxidant enzymatic activities were measured in the study as explicative variables related to plant stress responses in order to determine possible biostimulant or elicitor effects of cricket frass treatments during tomato cultivation under greenhouse conditions. The main findings of this study indicated that tomato plants responded in a dose dependent manner to cricket frass treatments, recalling the hormesis phenomenon. On the one hand, a 0.1% (w/w) cricket frass treatment showed typical biostimulant features, while on the other hand, 0.5 and 1.0% treatments displayed elicitor effects in tomato plants under evaluated conditions in the present study. These results support the possibility that low doses of cricket frass might be used in tomato cultivation (and perhaps in other crops) for biostimulant/elicitor input into sustainable production systems.

: To exploit the full potential of plants, it is essential to provide an adequate water balance during critical growth stages. With knowledge of the substrate’s matric potential, it is possible to realistically measure the amount of water available to the plant. The objective of this research is to study the effect of the matric potential of the substrate on the growth of beans, lettuce, sweet peppers, watermelon, and cauliflower plants. The research goal was to evaluate the effect of the matric potential on the main fertigation parameters of horticultural plants. The plants were cultivated at the University of Almería (Spain) in a controlled chamber in a pot with 250 mL of coconut fiber substrate from block propagation. For treatments T₁₅, T₃₀, T₄₅, and T₆₀, new irrigation was applied when easily available water (EAW) depletion levels of 15, 30, 45, and 60% were reached, respectively. The efficiency of the use of water (WUE), nitrate (NUE), and potassium (KUE) was measured. From T₁₅ to T₆₀, a significant effect was found for the absorption of water, nitrate and potassium, WUE, NUE, and KUE. T₆₀ reduced the plant growth by half. The largest growth was between 15 and 30% of the level of use of EAW. Two different models were constructed according to each plant. It is possible to have a small depletion in the available water and still have plant growth, if there is a balance between the air and water needs of the substrate.

Amaranthus viridis L. is a wild edible plant that occasionally is cultivated as an alternative crop because of its interest as a functional food and its adaptation to high-saline soils. In this work, leaves from A. viridis were compared with their grown in controlled environment (GCE) counterparts in a soilless system at electrical conductivities (EC) and different light exposures for assessing growth parameters, moisture, total phenolic and total flavonoid content, phenolic compound profiles, vitamin C, antioxidant activity, and antiproliferative activity against the HT–29 human colorectal cancer cell line. The highest biomass production was obtained using EC of 2.5 dS m⁻¹ and the AP67 Milk LED lamp. Vitamin C in wild samples ranged from 83.1 to 104.9 mg 100 g⁻¹ fresh weight (fw), and in GCE ones, it ranged from 112.3 to 236.7 mg 100 g⁻¹ fw. Measured by the DPPH and ABTS assays, the antioxidant activity was higher in wild than in GCE plants: the ranges for wild samples were in the 1.8–4.9 and 2.0–3.9 mmol of Trolox Equivalent (TE) 100 g⁻¹ dry weight (dw) ranges, and for GCE ones in the 1.3–1.9 and 1.5–2.2 mmol TE 100 g⁻¹ dw ranges, respectively. As for phenolic compounds, in wild samples, the range was from 14.65 to 22.70 mg 100 g⁻¹ fw, and these amounts were much higher than those found in their GCE counterparts, in which the range was from 2.58 to 5.95 mg 100 g⁻¹ fw. In wild plants three compounds, namely trans-p-coumaric acid, isorhamnetin-3-O-glucoside, and nicotiflorin, accounted for more than half of the total quantified phenolic compounds. The MTT assay revealed concentration- and time-dependent inhibitory effects on HT–29 cells for all checked extracts. Cancer cells were less influenced by extracts from GCE plants, which showed higher GI₅₀ compared to wild plants. This work improves knowledge on the growth parameters, phytochemical profiles, and biological activities of wild and GCE A. viridis.

Intercropping systems are a widely used agricultural practice by smallholder farmers to enhance food security and to use natural resources more efficiently. The objective of this study was to evaluate two lettuce cvs under an intercropping system. Enzymatic growth, yield and economic benefit were evaluated. The experiment was carried out from August to February in Jaboticabal (Brazil) using tomato plants as a main crop and Lucy Brown and Vanda cvs of lettuce as secondary crops. The catalase, superoxide dismutase and peroxidase activity of lettuce plants was analyzed. Mineral nutrient content, growth, yield parameters and commercial economic benefit were measured. Significant differences in stress and activity enzymatic indicators were found versus cultivars of lettuce. The loss of abiotic factors such as radiation or its effect on enzymatic stress indicators was greater than its effect on yield. Yield loss in the intercropping systems was different for each cultivar system, with cv Lucy Brown showing greater yield loss than cv Vanda. Economic benefit was only found for the Vanda lettuce cv. Although the benefits of intercropping have been demonstrated as very appropriate cultural management, the choice of cultivars involved might be the determining factor for the agronomic success of the system.

Root-knot nematode Meloidogyne enterolobii is the main phytosanitary problem of guava cultivation in Brazil. Among the strategies to manage the problem, the best prospects are in identifying or developing cultivars or rootstocks that are resistant to this nematode. To identify plants with potential as rootstocks for guava, the reaction of araçá (wild guava) to M. enterolobii was assessed in a greenhouse experiment. Seven araçá species were evaluated (Eugenia stipitata, Psidium acutangulum, P. cattleyanum ‘yellow’, P. friedrichsthalianum, P. guajava var. minor, P. guineense, and Psidium sp.). The plants were inoculated with a suspension of 3,000 eggs of M. enterolobii, using eggplant as control treatment. The parameters fresh root mass, number of eggs and second stage juveniles (J2) per root system, the reproduction factor (RF = Pf/Pi), and araçá reaction were determined during the experiment. RF of the araçá species E. stipitata, P. cattleyanum ‘yellow’, and P. friedrichsthalianum was less than one (RP < 1), therefore resistant to M. enterolobii. The araçá trees had good root system development and the susceptible plants showed many root galls, high number of eggs and J2, and Fusarium solani and Rhizoctonia solani root rot. The araçá species, P. cattleyanum ‘yellow’, P. friedrichsthalianum, and E. stipitata are resistant to M. enterolobii and can be tested as potential guava rootstocks.

The effect of silicon (Si) in the nutrient solution on the fruit development of 2-year-old blueberry plants (Vaccinium corymbosum L. cv. Ventura) was studied. Si was applied to the nutrient solution at a dose of 0.0, 0.6, and 1.2 mM. The parameters of fruit, stems and leaves growth, firmness, and biomass were measured. Fertigation in conjunction with traditional spread fertilization could improve the growth and yield of highbush blueberry to find the optimal method to control decay and prolong the quality of blueberries after harvest. The blueberry fruit has a light-blue appearance because its blue-black skin is covered with a waxy bloom. This layer is easily damaged or removed during fruit harvesting and postharvest handling. Si enhances the resistance of this layer to damage. A 2-year study was done to compare the effects of silicon fertigation and silicean sand and coir fiber as substrates on growth and availability of nutrients for blueberry plants during establishment of highbush blueberry (Vaccinium corymbosum L. “Bluecrop”). The results of experiment indicated that the application of Si had better benefit on the fruit growth of blueberry plants in coir fiber, than the effect that was observed in the sand substrate. The results should improve our understanding for better preservation of postharvest quality of blueberry fruit.