Gas exchange, root hydraulic conductivity, water use efficiency and the growth of Toona ciliata clones and seedlings/Trocas gasosas, condutividade hidraulica das raizes, eficiencia do uso da agua e crescimento de mudas clonais e seminiferas de Toona ciliata

• Published in: Ciência florestal 2019-04, Vol.29 (2), p.715
• Main Authors: de Oliveira, Taiane Pires de Freitas, Barroso, Deborah Guerra, Figueiredo, Fábio Afonso Mazzei Moura de Assis, Barros, Thais Chagas, Gambetta, Gregory A, Campostrini, Eliemar
• Format: Article
• Language: English
• ISSN: 1980-5098; 1980-5098
• DOI: 10.5902/1980509825604

Forest plantations established with seedlings have heterogeneity and are difficult to manage, so an alternative is the use of clones with high productivity. In addition, clonal plants differ in the structure of the root system that can influence the water and nutrient uptake efficiency and therefore productivity. We evaluated leaf gas exchange, root hydraulic conductivity, and water use efficiency of Toona ciliata clonal cuttings and the seedlings growth. The study was performed in a completely randomized design with four treatments: a) TC3 clone; b) TC9 clone; c) TC15 clone and d) seedlings with five replicates and ten plants per plot. On the 120th day, the net photosynthetic rate, transpiration and stomatal conductance were evaluated between 12:00 and 13:00 hours and the values calculated as efficient, instantaneous (A/E) and intrinsic (A/gs) water use were calculated. Hydraulic root conductivity ([k.sub.root] was obtained by applying increasing pressures (0.1, 0.2, 0.3, and 0.4 MPa) using Scholander chamber. The height, stem diameter, leaf area, dry mass of shoot and root, length, diameter, surface area and root volume were also determined. The data were submitted to Pearson's correlation and analysis of variance, comparing by Tukey's test (5%). The genetic materials studied presented an equal capacity of water absorption and transport by the roots, even though they exhibited a visual anatomical differences of the root system. Although, the clones exhibited low transpiration and net photosynthetic rates, they were generally more efficient in water use, and the TC3 and TC9 clones were more efficient to convert the assimilated carbon to biomass. Keywords: Photosynthesis; Root hydraulic conductivity; Toona ciliata, Cuttings As plantações florestais estabelecidas com mudas apresentam heterogeneidade e dificuldades de manejo. Assim, uma alternativa a estes obstáculos é o uso de clones com alta produtividade. Além disso, as plantas clonais diferem das plantas seminíferas na estrutura do sistema radicular, o que pode influenciar a eficiência na absorção de água e de nutrientes minerais e, portanto, a produtividade. Nesta pesquisa, avaliaram-se as trocas gasosas foliares, a condutividade hidráulica da raiz, a eficiência no uso da água e o crescimento de plântulas de estacas clonais e de plantas propagadas por semente da espécie Toona ciliata. O estudo foi realizado em delineamento inteiramente casualizado com quatro tratamentos: a) clone TC3; b) clone TC9; c) c