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The increasing incidence of heat stress due to global climate change poses a significant challenge to avocado (Persea americana) cultivation, particularly in regions with intense solar radiation. This review evaluates sun protection strategies, focusing on the efficacy of different sunscreen products such as kaolin, titanium dioxide, and calcium oxide in mitigating thermal stress in avocado trees. The application of these materials was shown to reduce leaf and fruit surface temperatures, improve photosynthetic efficiency, and enhance fruit quality by preventing sunburn and dehydration. Despite these benefits, challenges remain, including the optimal timing and dosage of application, and the potential residue impacts on fruit marketability. The review emphasizes the need for ongoing research to develop more effective formulations and to integrate these sun protection strategies with other agronomic practices. The role of extension services in educating producers about the proper use of these technologies is also highlighted as crucial for the successful adoption of sun protection measures in avocado farming. [ABSTRACT FROM AUTHOR]

The yellow (Passiflora edulis) and sweet (Passiflora alata) passion fruit plants hold significant economic importance in tropical fruit cultivation, valued not only for the quality of their fruit but also for their medicinal properties. Conventional propagation through seeds faces challenges due to irregular and slow germination, affecting the time required for seedling formation and the viability and uniformity of plantations. The use of plant growth regulators has been explored as a strategy to overcome these barriers, improving both the rate and uniformity of seed germination. This study aimed to evaluate the influence of seed imbibition with plant growth regulators on the germination and subsequent growth of yellow and sweet passion fruit seedlings. Gibberellic acid (GA3) and GA4+7 combined with 6-benzyladenine (GA4+7+6BA) were applied in five different concentrations (0, 250, 500, 750, and 1000 mg L−1 a.i.). The experiments were conducted in both laboratory and greenhouse conditions, following a completely randomized design with a 2 × 5 factorial scheme. The varieties tested were 'BRS Mel do Cerrado' for sweet passion fruit and 'IAC-275' for yellow passion fruit. Quantitative parameters, such as germination percentage, germination speed index, fresh and dry biomass of roots and shoots, and enzymatic activity, were assessed. The results indicated that GA3, at higher concentrations, significantly enhanced both germination percentage and speed index in both Passiflora alata and Passiflora edulis when compared to the control. Additionally, seedlings treated with GA3 showed a marked increase in shoot and root biomass, particularly at concentrations of 500 and 750 mg L−1. Enzymatic assays revealed heightened catalase and peroxidase activities in treated seedlings, indicating improved stress tolerance. In contrast, the GA4+7+6BA treatment showed less pronounced effects on seedling growth. Overall, GA3 was more effective in enhancing germination and seedling growth in both species, suggesting its potential application in improving the propagation of passion fruit. [ABSTRACT FROM AUTHOR]

The phenolic profile and antioxidant activity of whole grape juices from Vitis labrusca and Brazilian hybrids in two training systems were analyzed. Genotypes of V. labrusca ('Bordô' and 'Isabel') and Brazilian hybrids ('IAC 138-22 Máximo' and 'BRS Violeta') were grafted onto the rootstock 'IAC 766 Campinas' (106-8 'Mgt' × Vitis caribaea) and trained on low and high trellis. After harvest, the grapes were destemmed and the berries macerated in a roller crusher. Following hot extraction without pressurization of the pomace and gentle pressing of the blend (skins, must, and seeds), the juices were bottled in amber glass bottles and pasteurized. The physicochemical and colorimetric parameters of the juices, as well as the levels of flavonoids, phenolic compounds, total monomeric anthocyanins, antioxidant activity, and polyphenolic profile, were evaluated. The juices were also subjected to sensory analysis (CAAE: 65549817.7.0000.5411). There was broad variation in all assessed characteristics. The results obtained demonstrate that the training system and grape genotype used in juice production are highly related to the presence of sugars, acidity, and bioactive compounds. Juices made from 'Bordô', 'IAC 138-22 Máximo' and 'BRS Violeta' grapes stood out from 'Isabel' juices, the main grape variety used in Brazilian juice and wine production. All juices contain bioactive compounds in considerable concentrations, indicating beverages with high antioxidant activity and, consequently, high biological potential, with the use of high trellis in vine cultivation potentially increasing concentrations. [ABSTRACT FROM AUTHOR]

The interaction between variety, rootstock, and trellis height is important for grapevine management, mainly for producing new varieties of grapes for juice and wine in new wine-growing regions with high production potential. Then, this study aimed to evaluate the rootstocks and trellis height influence on photosynthesis, biochemical, and yield performance for grapevine hybrids. The experiment was carried out in a randomized block design using two factors, rootstocks ('IAC 766' and '106-8 Mgt') and trellis height (until 1.6 and 2.0 m), evaluated for two grapevine hybrids (IAC 138-22 'Maximo' and 'BRS Violeta'). During grapevine flowering, it was evaluated photosynthesis and biochemical performance, for this, the gaseous exchanges were measured using the open system photosynthesis equipment with a CO2 analyzer and water vapor by infrared radiation, being net assimilation rate of CO2, stomatal conductance, transpiration rate, internal CO2 concentration, water use efficiency, carboxylation efficiency (Rubisco), and the flux density of photosynthetically active photons. At the stages of grapevine flowering and ripening berries were evaluated the antioxidant enzymes (peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT)), total soluble proteins, chlorophylls, and SPAD. The interaction between rootstock and trellis heigh influenced varieties' photosynthesis, biochemical, and yield performance. In conclusion under subtropical conditions, better photosynthesis, biochemical, and yield performance were observed when both cultivars were grafted on the 'IAC 766' rootstock. The 'IAC 138-22 Maximo' was trained until 2.0 and grafted on the 'IAC 766' rootstock, increasing grape production and photosynthesis efficiency. In addition, this variety was more productive than 'BRS Violeta'. [ABSTRACT FROM AUTHOR]

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