Differential Physiological Responses to Different Drought Durations among a Diverse Set of Sugarcane Genotypes

Drought severely limits sugarcane productivity in many regions of the world. This study characterized physiological responses to different drought durations in a diverse set of sugarcane genotypes in two crop cycles (plant and ratoon cane). A split-plot design was used where three drought treatments, namely, no drought (SD0), short-term drought (SD1), and long-term drought (SD2), were assigned to main plots and six diverse sugarcane genotypes to subplots. Drought reduced photosynthesis, leaf area index, and biomass yield. However, the study found significant differences in physiological responses to drought among genotypes in both crops. F03-362 (F1), KK09-0358 (BC1), and KK3 (cultivar) demonstrated greater tolerance to drought by maintaining comparatively higher photosynthetic activity, while KK09-0939 (BC2) and TPJ04-768 (BC1) were more sensitive. KK3 and UT12 (cultivar) consistently maintained comparatively higher levels of photosynthesis under drought in the ratoon crop, although stomatal conductance values were comparable to those of other genotypes. Drought significantly reduced dry matter in all genotypes, but more so in the two cultivars. The study demonstrated variable levels of sensitivity to drought among diverse genotypes with different physiological responses being induced by different drought treatments. This information is useful for sugarcane production management and breeding programs.