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Understanding the growth patterns of genotypes optimizes their selection and management. The objective of this study is to investigate the seasonal variations in the morphology and biochemistry of Coffea canephora clone leaves, considering climatic conditions and the maturation cycle. Morphological characteristics and carbohydrate contents of the leaves were analyzed throughout the growth cycle. A nonlinear logistic model was applied, and critical points of the leaf emission rates of plagiotropic branches were determined. Leaf growth was greater at higher temperatures during the rainy periods and lower at milder temperatures during the dry season. Genotype 143 exhibited the largest leaf width in spring, while 104, A1, and P2 had the largest leaf width in summer. The logistic model was suitable for describing leaf emission, with the critical points of genotype 143 being earlier, while P2 displayed a longer leaf emission cycle. The peak growth period influenced the quantities of starch and total soluble sugars in the leaves. The dormancy period showed a higher availability of reducing sugars. Pearson correlation indicated significant coefficients between temperature, precipitation, photoperiod, and foliar characteristics. The results obtained serve as a reference for future investigations, particularly in response to environmental challenges.

The aim was to investigate the morphological, photosynthetic, and hydraulic physiological characteristics of different genotypes of Coffea canephora under controlled cultivation conditions. Growth, conductance, and hydraulic conductivity of the root system of 16 C. canephora genotypes were evaluated in Experiment 1 (November 2013). In Experiment 2 (December 2014), in addition to the previous characteristics, gas exchange, photochemical efficiency, leaf water potential, and leaf hydraulic conductivity were investigated in five genotypes. No significant differences were observed in specific leaf hydraulic conductance, stomatal density, or gas exchange. The correlation between root hydraulic conductance and leaf area and dry mass indicates a physiological balance, reflecting the root system's ability to supply water to the aerial parts and maintain leaf water potential and photosynthetic activity during periods of high atmospheric evapotranspiration. These characteristics are important for genotypes cultivated under low water supply and high evaporative demand, even under irrigation., Competing Interests: The authors declare that they have no conflict of interest., (Copyright: © 2024 Machado Filho et al.)

This study investigated the effects of recurrent water deficit on drought tolerance traits in black pepper ( Piper nigrum L.) 'Bragantina'. Plants were subjected to three cycles of water deficit followed by recovery periods. Water deficit reduced stomatal conductance, photosynthesis, transpiration, and water potential while increasing water-use efficiency. In addition, intercellular CO 2 concentration, leaf temperature, root starch, and adaptive morphological characteristics in leaves and roots increased. Despite these adaptations, plants did not recover vegetative growth after rehydration. The primary tolerance mechanisms observed included increased abaxial epidermis thickness, stomatal density, fine roots, periderm thickness, and starch accumulation in roots. Although gas exchange and leaf water potential were restored, vegetative growth did not fully recover. This study highlights the response of black pepper to recurrent water stress and the underlying mechanisms of its drought tolerance., Competing Interests: The authors declare that they have no conflict of interest., (Copyright: © 2024 Ferreira et al.)

This study investigates how cocoa rootstocks respond to flooding and post-flooding conditions, offering insights for cocoa plantation sustainability in flood-prone areas due to climate change. We studied Theobroma cacao L. rootstocks for 60 d of flooding and 30 d post-flooding, grafting PS-1319 scions onto five rootstocks (TSH-1188, Cepec-2002, Pará, Esfip-02, SJ-02). Photochemical performance remained stable across rootstocks, while flooding progressively reduced electron transport efficiency. Photochemical damage emerged after 7 d, worsening occurred at 19 d. Although post-flooding efficiency improved, recovery time was insufficient for full restoration. Stem diameter increased less in Esfip-02. TSH-1188 had the highest stem dry mass during flooding and the most root and total dry mass during post-flooding. SJ-02 had the lowest stem dry mass and post-flooding total dry mass. Principal component analysis revealed stem and root development as a key for recovery. SJ-02 and Esfip-02 showed lower flooding tolerance and recovery, while TSH-1188 and Pará exhibited higher resilience., Competing Interests: The authors declare that they have no conflict of interest., (Copyright: © 2023 Pinto et al.)

Studies that simulate recurrent drought events with subsequent episodes of rehydration better reflect natural conditions and allow visualization of differential acclimatization responses resulting from memory and tolerance mechanisms. Piper aduncum and Piper tuberculatum were grown in a greenhouse and were subjected to three successive cycles of drought and subsequent rehydration. After suspending irrigation, gas exchanges were measured daily with IRGA. When stomatal conductances close to zero were obtained, the plants were rehydrated and kept irrigated. In P. tuberculatum , stomatal conductance was always higher after periods of rehydration compared to the period before the drought, while the transpiration rate was lower only during the drought. The damage to the photosynthetic apparatus was caused by the influence of the interception of the flow of electrons in the transport chain. We came to the conclusion that the dehydrated plants showed an alert signal, which triggered response mechanisms to prevent or deal with the water stress situation., Competing Interests: The authors declare that they have no conflict of interest., (Copyright: © 2023 Cerri Neto et al.)

This study evaluated the side-cleft grafting in native species of the genus Piper ( Piper aduncum L., Piper hispidum Sw., and Piper tuberculatum Jacq.) with BRS Kottanadan pepper cultivar as rootstocks (Experiment 1). The top-cleft grafting was evaluated in native species Piper arboreum Aubl., P. aduncum , and P. tuberculatum with Balankotta pepper cultivar as graft using black pepper cv. Bragantina (Experiment 2). Black pepper cv. Bragantina autograft was considered as control. The rootstock P. tuberculatum showed initial incompatibility with the cv. Bragantina, with survival of about 34.8% (side) and 62.5% (top) and total inhibition of graft shooting. The side and top graft on P. aduncum resulted in 84.0 and 47.5% of survival, respectively. The JIP-test parameters indicated better photochemical efficiency in the species grafted using the method of side-cleft grafting. Finally, the initial compatibility was associated with greater survival, shooting, and better energy flow through the electron transport chain., Competing Interests: The authors declare that they have no conflict of interest., (Copyright: © 2023 Crasque et al.)