Dynamic Recovery of Canopy and Growth Traits in Diverse Sugarcane Genotypes Following Early-Season Drought

Sugarcane biomass and yield decline under drought, and interspecific hybridization may improve tolerance, but how non-destructive traits such as canopy size and leaf area index (LAI) respond across genotypes under varying drought duration and recovery remains unclear, limiting their use in breeding selection. This study evaluated non-destructive traits in six sugarcane genotypes under field capacity (FC), short-duration drought (SD), and long-duration drought (LD) using a split-plot RCBD with four replications. Canopy height, canopy width, LAI, green leaf number, tiller number, leaf dry weight, and stalk dry weight were measured at 3, 6, and 8 months after transplanting (MAT). By 3 MAT, LD reduced canopy height, LAI (by up to approximately 30% relative to FC), and green leaf number in most genotypes. By 6 MAT, F03-362 showed reduced canopy height, width, green leaf number, and tiller number under drought, with LAI increasing during recovery, whereas KK3 stayed stable in most traits except LAI, which declined under LD. By 8 MAT, canopy height under LD had recovered to match or slightly exceed that under SD in most genotypes, and F03-362 produced the highest biomass of all genotypes under every water regime and, at 6 MAT, showed a proportional biomass decline close to the smallest among all genotypes, although this relative advantage narrowed by 8 MAT, whereas total biomass under SD and LD averaged approximately 34% lower than under FC across genotypes and stages overall. F03-362 and KK3 thus emerge as complementary genotypes for breeding drought-tolerant sugarcane, F03-362 through high absolute biomass potential with a favorable proportional response at 6 MAT, and KK3 through green leaf number stability under short-duration drought, offering practical, repeatedly measurable traits for early selection under limited sample size.