γ-Aminobutyric acid (GABA), a nonprotein amino acid, can accumulate in plants in response to abiotic stresses. The effects of postharvest treatments on endogenous GABA concentrations and exogenous GABA on whole horticulture product quality has recently received attention. However, knowledge of the effects of mechanical damage events such as peeling and cutting on GABA concentrations of fresh-cut products is limited. In this study, concentrations of GABA and antioxidants including total phenolics and ascorbic acid in fresh-cut cantaloupe, pineapple, and cauliflower during storage at 5 °C for 9 days were investigated. We found that GABA accumulated in fresh-cut pineapple and cauliflower during storage, but that the increase in cantaloupe was not significant. Total phenolics, total ascorbic acid, and dehydroascorbic acid (DHA) remained stable in fresh-cut cantaloupe and cauliflower. In pineapple, however, total phenolics and total ascorbic acid concentrations decreased, whereas the DHA concentration increased. No correlation was found between GABA and antioxidants in fresh-cut cauliflower and cantaloupe; however, GABA was negatively related to antioxidants, including total phenolics and total ascorbic acid, in fresh-cut pineapple. The results show that GABA accumulation may represent a stress response to damage that occurs during the preparation of fresh cut products, but that the degree of response is affected by the specific product. Further research of GABA metabolism in response to minimal processing, including GABA biosynthesis, in a wider range of horticultural products and relationships with antioxidants is warranted.
As anthropogenic activities have facilitated the spread of heavy metals into the environment, plants have been identified that may have the ability to tolerate exposure to high levels of these metals. Industrial hemp (Cannabis sativa L.) has been suggested as potentially having the ability to accumulate elevated concentrations of some contaminants from soils, including cadmium (Cd), a heavy metal that has been linked to serious health risks to humans. Therefore, there is an interest to document the ability of hemp to tolerate exposure to Cd to determine if there is a risk when products for medicinal consumption are made from the hemp plant. The objectives of this study were to perform histochemical localization of Cd at the cellular level and document potential changes in plant tissues in response to hemp exposure. Plants were grown in hydroponic solutions for 4 weeks and then exposed to either 0 or 10 mg·L−1 Cd for 17 days and harvested. There were no differences in dry weights (dw) of leaves, stems, and roots among treated and control 17 days after treatment (DAT). However, plants exposed to 10 mg·L−1 Cd had Cd concentrations of 1448.0 mg·kg−1 dw in roots and 23.2 mg·kg−1 dw in leaves at 17 DAT, whereas Cd was not detected in roots or leaves of control plants. On staining with dithizone, Cd was primarily localized in leaf epidermis, mesophyll, and trichomes, and in root rhizodermis, cortex, and pericycle in hemp plants exposed to 10 mg·L−1 Cd. Image analysis was able to further quantify these results based on area stained. Our results suggest that Cd is primarily accumulated throughout hemp roots, with lesser amounts translocated to the leaves, where it may be localized in the epidermis and trichomes.
In Honduras, tomato (Solanum lycopersicum L.) is an economically important crop for farmers because of its high domestic consumption, year-round production, and high export potential. However, tomato production faces challenges such as diseases and pests and is confounded by climate change, all of which reduce productivity and quality. Evaluating the adaptation of tomato cultivars is critical to ensuring the long-term sustainability and resilience of the horticulture sector in the region. The objective of this study was to identify tomato lines with adaptability, high yield, pest, and disease resistance under greenhouse and open field production conditions for the Honduran market. Ten tomato lines and two commercial hybrids were evaluated between Feb and Jul 2022 in San Antonio de Oriente, Francisco Morazán, Honduras. Desirable traits related to vegetative growth, productivity, fruit quality, and resistance to insect pests and diseases were measured. Seven lines were highly adapted and had high vegetative growth. The tomato lines were not significantly different in terms of tomato yellow leaf curl disease and late blight disease index; however, the fruit borer susceptibility varied, with AVTO1908 being the most susceptible. The highest performing line was AVTO1903, which had the greatest total marketable yield in both the open field (101.3 t⋅ha−1) and greenhouse (62.1 t⋅ha−1). Additionally, AVTO1903 and AVTO1915 had good quality traits (roundness index, total soluble solids, and dry matter), thus demonstrating their potential for sustainable and high-yielding cultivation in Honduras. The growth and productivity of the tomato lines were highly influenced by the environment. This work highlights the advantages of introducing exotic cultivars to combat the effects of climate change and ensure sustained production; however, further research is needed to ensure that local farmer and consumer demands are met.
Cover crops between rows in orchards can improve the development of soil resources and increase agricultural productivity. However, there have been few reports of cover crops that can act as a “green manure” in apple orchards across arid and semiarid zones. This study investigated the effects of planting interrow vegetation on soil properties and apple tree performance during a 32-month experiment. There were six treatments: clean cultivation as a control; natural grass planting; planting with ryegrass; planting with alfalfa; planting with tall fescue; and planting with villous wild pea cover crops. The treatments primarily affected the 0- to 20-cm surface soil layer. Soil carbon, nitrogen, and enzyme levels initially decreased (during the first 12–24 months); then, they increased (24–32 months). The cover crops significantly increased nutrient contents (soluble organic carbon, microbial carbon and nitrogen, alkaline dissolved nitrogen, nitrate nitrogen, and ammonium nitrogen) in the 0- to 20-cm soil layer by more than 19.6% and increased the related enzyme activities by more than 25.2%. The alfalfa and wild pea alleys had a stronger effect on the soil environment than the control, natural grass, ryegrass, and tall fescue alley treatments; however, after 32 months, the alfalfa treatment inhibited fruit tree growth and development. This was unexpected because alfalfa seemed to have a positive effect on soil fertility characteristics. Under local ecological conditions, villous wild pea had the greatest effect on apple orchard productivity and significantly increased short branching by 15.9%, fruit weight per fruit by 12.6%, yield per plant by 8.6%, and soluble sugar content by 10.5% compared with clean cultivation. The correlation analysis showed that there were significant or highly significant positive correlations between fruit tree performance and soil carbon, nitrogen, and enzyme activity levels as the soil layer depth increased. Therefore, under local ecological conditions, cover crops have a greater effect on orchard surface soil fertility than on deeper soils, and intercropping with villous wild pea potentially produces the greatest improvement in apple orchard productivity.
To investigate and compare hardwood species based on their carbon (C) and nitrogen (N) storage capacity, a study of the C and N content of the bark and wood of nine common hardwood broadleaves in Novi Pazar, southwestern Serbia, was conducted. Compared with sycamore maple, Norway maple, common ash, common hornbeam, black locust, European beech, Turkey oak, and sessile oak, field maple has the highest C/N ratio in wood (37.05 ± 3.23), representing the best hardwood species for biomass production.