Biomass analysis and selection of sugarcane genotypes for drought tolerance

Abstract

In a completely randomized greenhouse pot trial, 26 sugarcane genotypes were evaluated under irrigated and water stress conditions during the formative growth phase (90 – 117 days after planting). The evaluation was based on visual assessment at 117 days after planting and measuring agronomical parameters of cane, leaf, root and biomass over four time intervals, viz. 90, 101, 109 and 117 days after planting. An ANOVA showed that the genotypes possessed high degree of diversity, in the selection process for drought tolerance. The interaction, genotype x water treatment, was highly significant for cane height, cane girth, root length, root fresh weight, root bulk density, biomass fresh weight and biomass dry weight. At the formative stage, cane height and cane girth were the only practically viable parameters; best reflected by biomass dry weight, where correlation coefficient was (r = 0.517) and (r = 0.314) for cane height and girth, respectively. The 26 genotypes were classified into three categories in response to water stress: 5 tolerant, 11 moderate and 10 sensitive. Visual evaluation matched the evaluation based on biomass analysis in 16 cases, nearly matched in 9 cases and differed in 1 case. Visual evaluation is fast, inexpensive and relatively accurate and it may be a useful predictor for drought tolerance in screening large number of genotypes. However, more objectively, the procedure highlights the importance of biomass analysis in the evaluation of reasonable number of genotypes in response to water stress. The study allowed for selecting drought tolerant sugarcane genotypes suitable for cultivation in Ramu Valley and Morobe Province of Papua New Guinea.