Parâmetros morfofisiológicos envolvidos na tolerância à seca de coffea canephora em cenários de déficit hídrico controlado

Abstract

The negative impacts of climate change are expected to affect various plant species, including coffee. In the state of Espírito Santo, Conilon coffee holds significant economic importance. However, the main obstacle faced in coffee cultivation in Espírito Santo is the lack of irrigation. This work aimed to identify individuals that present morphophysiological characteristics of greater performance in different conditions of water stress among the studied parents contrasting to drought, 120 (tolerant) and the clone 109 (susceptible). To address this issue, a randomized block design was implemented in a greenhouse, with four replications and a total of 112 evaluated plants. The study involved 14 clones, including progenies from the 120 x 109 cross and the 109 x 120 cross, along with the two parent clones (109 susceptible and 120 tolerant). Two conditions were considered: an irrigated control and varying levels of water stress. Data was collected between April and June 2019, measuring water stress levels at 25%, 40%, 55%, 70%, and 0%. The evaluation dates were as follows: 1st) April 19, 2nd) May 3, 3rd) May 17, 4th) May 31, and 5th) June 15 (recovery period), concluding on June 28, 2019. The results revealed that all parameters examined were influenced by water deficit, with more severe effects observed as the intensity of water stress levels increased. Clone 7T exhibited the lowest height, while the most favorable outcomes were obtained for leaf water potential, root dry mass, and plagiotropic branch length under water stress conditions. Leaf dry mass was nearly halved across all clones due to water deficit. Furthermore, water stress levels influenced all photosynthetic variables investigated, with clones 120 and 4S maintaining their regulated photosynthesis rate irrespective of irrigation or recovery. The FAI_BLUP index enabled the selection of superior genotypes with drought tolerance characteristics in C. canephora. Among the clones, 7T displayed the most promise, while clone P6 was the most susceptible in relation to the target ideotype. The traits studied exhibited desirable genotypic gains. Once characterized, these clones can be utilized in improvement efforts, employing suitable strategies and new crosses to obtain more adapted genetic materials.