Screening of cacao clones for drought tolerance by assessing predawn leaf water potential, growth, and leaf gas exchange

• Published in: Plant stress (Amsterdam) 2023-12, Vol.10, p.100245, Article 100245
• Main Authors: Santos, Ivanildes Conceição dos, Silva, Gonçalo Santos, Silva, João Paulo Lima, Souza, Jadiel de Santana, Santos, Martielly Santana dos, Souza Junior, José Olímpio de, Almeida, Alex-Alan Furtado de, Corrêa, Ronan Xavier, Baligar, Virupax Chanabasappa, Zhang, Dapeng, Calle-Bellido, Juan, Jia, Haiyan, Ahnert, Dário
• Format: Article
• Language: English
• Subjects: Clonal genotypes; Drought tolerance; Plant growth and photosynthesis; Theobroma cacao
• ISSN: 2667-064X; 2667-064X
• DOI: 10.1016/j.stress.2023.100245

•Clonal genotypes more drought tolerant maintained leaf water potential values with increasing water deficit in soil, under greenhouse conditions.•Clonal genotypes presented significant differences in the physiological characteristics when subjected to water deficit in the soil.•DTC clonal genotypes 7, 8, 11, 14, 15, 17, 18, 26, 40, 41 57, 61, 65 66, 70, 78, 85, 88, 91, 92, 93 and 102 were selected as drought tolerant, mainly due to the maintenance of the values of physiological traits.•Drought tolerance indices were efficient in identifying the DTC more tolerant to water deficit in the soil. Drought in cacao-producing regions worldwide is causing a decrease in yield and, in severe cases, leading to plant death. This primarily affects small farmers who lack sufficient financial resources or water availability to irrigate their plantations. This study aimed to test 83 cacao clonal genotypes for drought tolerance by evaluating their physiological and morphological features. These genotypes, referred to as drought-tolerant cacao (DTC) genotypes, were selected through mass selection from regions of Bahia, Brazil, severely affected by prolonged droughts. Seedlings of the DTC clonal genotypes and two control clones (CCN 51- drought-intolerant and CEPEC 2002 – drought-tolerant) were obtained from rooted cuttings of plagiotropic branches and evaluated under greenhouse conditions. Three experiments (EXP 1, 2, and 3) were conducted using a randomized block design, with three replications each and two plants per replication of each clonal genotype to test for drought tolerance. Data analyses were conducted using univariate and multivariate statistical analysis. DTC and control clones were subjected to varying soil moisture contents [70, 60, 50, 40, and 30 % of field capacity (FC)] and their controls (maintained close to 100 % of FC) for approximately 40 to 60 days. The results revealed significant statistical differences in growth variables before the plants were subjected to drought. They were categorized based on vigor into three, four, and three groups for EXP 1, 2, and 3, respectively during cluster analysis. DTC and control clones subjected to drought (70, 60, 50, 40, and 30 % of FC) exhibited significant statistical differences in physiological traits compared to the traits of their respective controls (100 % of FC). However, plant growth remained largely unchanged under drought stress (30 or 40 % of FC). DTC clonal genotypes 15, 17, 23, 41, 61, 66, 90, 91, 92,