Drought stress is the main abiotic factor limiting soybean yield. The memory of recurrent water stress can provide greater efficiency in minimizing the negative effects of drought. Thus, the aim of this work was to understand the temporal adjustments in photosynthesis presented by soybeans when exposed to recurrent drought at the beginning of the flowering and grain filling stages. The experiment was carried out in a randomized block design with five replications, consisting of four treatments: i) WS-R1 (moderate water deficit at the beginning of flowering), ii) WS-R5 (severe water deficit during grain filling), iii) WS-R1+R5 (moderate water deficit at early flowering and severe water deficit during grain filling), and iv) WW (well-watered condition). Severe stress caused reductions in gas exchange parameters and the relative water content, with increased initial fluorescence and water use efficiency. The plants from the WS-R5 and WS-R1+R5 treatments showed a reduction in the apparent rate of electron transport in photosystem II (PSII), photochemical quenching, and effective quantum yield of PSII, as well as increased nonphotochemical quenching values. Furthermore, the proline concentration in the leaves was higher in plants from the WS-R1+R5 treatment, contributing to the greater ability to maintain turgid cells compared to the WS-R5 plants. The photosynthetic adjustments related to faster isohydric responses and photoprotective mechanisms in soybean plants subjected to recurrent drought allowed the maintenance in the weight or number of grains compared to plants without water restriction, demonstrating the activation of efficient memory mechanisms of response to water stress.

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Com o intuito de verificar alterações que o processo de enxertia desencadeia no crescimento da cultura do tomate, realizou-se um experimento em condições de campo na Universidade Federal de Viçosa – Campus Florestal. Foram utilizados duas cultivares de porta-enxerto, sendo elas TD1 e Woodstock, e a cultivar Débora Victory como enxerto e pé franco. O delineamento experimental utilizado foi de blocos ao acaso, com 5 repetições. A amostragem das plantas foi realizada nos dias após o transplantio 15; 30; 45; 60; 75; 90; 105 e 120, e colocadas em estufa com circulação forçada de ar, à temperatura de 75ºC, até atingir massa constante, com o intuito de avaliar matéria seca de folhas (MSF); caule (MSC); inflorescências (MSI); frutos (MSFr) e total (MST), obtidos mediante pesagens diretas de cada órgão da planta. Foram determinadas as curvas de acúmulo de matéria seca de caule, folha, inflorescências, frutos e total. O tratamento Woodstock apresentou-se com declínio, por volta de 60 a 80 dias, de MSC, MSF e MST. Desse modo, podemos concluir que os porta-enxertos influenciaram positivamente a produtividade da cultivar Débora Victory, uma vez que promoveram maior matéria seca de frutos do que quando utilizada como pé franco. O porta-enxerto Woodstock proporcionou à cultivar Débora Victory menor matéria seca de caule e folha do que o TD1. No entanto, tal comportamento foi para manter semelhante a matéria seca de fruto deste último porta-enxerto.