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Path analysis for selection of drought tolerant sugarcane genotypes through physiological components

da Silva, Paulo Pedro, Soares, Lailton, da Costa, João Gomes, da Silva Viana, Luciana, de Andrade, Júlio César Farias, Gonçalves, Eduardo Rebelo, dos Santos, João Messias, de Souza Barbosa, Geraldo Veríssimo, Nascimento, Velber Xavier, Todaro, Adriana Reis, Riffel, Alessandro, Grossi-de-Sa, Maria Fatima, Barbosa, Márcio Henrique Pereira, Sant’Ana, Antônio Euzébio Goulart, Neto, Cícero Eduardo Ramalho
Industrial crops and products 2012 v.37 no.1 pp. 11-19
clones, drought, drought tolerance, environmental factors, experimental design, field capacity, genotype, greenhouses, humidity, photosynthesis, plant growth, selection index, soil water regimes, stomatal conductance, sugarcane, sugarcane soils, water stress
Water deficit is among the main environmental factors limiting agricultural productivity of sugarcane in Northeast Brazil by affecting virtually every aspect of plant growth, with consequent reduction of the agro-industrial productivity of this crop. This study aimed to use path analysis to evaluate the physiological components of sugarcane under two water conditions, with photosynthesis as the basic variable, in order to obtain subsidies that can help the genetic breeding of this crop by selection of superior clones with drought tolerance. The experiment was carried out in a greenhouse with a completely randomized experimental design, 4×2 factorial arrangements (four sugarcane genotypes×two soil moisture regimes: control, with 80–100% available water and stressed, with 0–20% water available) and with four replications. Each plot consisted of one pot with 12kg of substrate containing one plant. Treatments were maintained at a humidity close to field capacity with daily replacement of the evapotranspired water with a water supply for 66 days of cultivation for treatments under stress. Evaluations were conducted on the fourth day after severe water stress at 70 days of cultivation. Data from nine physiological variables were considered, with six of these being used in the model after exclusion of those that were contributing to multicollinearity. Variables used in path analysis were enough to explain the variation found in photosynthesis under both water conditions. Stomatal conductance, transpiration and the SPAD index should be considered as a priority in breeding programs for sugarcane aiming to get more productive and tolerant genotypes to water stress, and selection indexes should be used with due consideration of these variables to promote gains in photosynthesis.