**4.2 Growth analysis**

The leaf area fairly gives a good idea of the photosynthetic capacity of the plant. The reduction in leaf area index (LAI) under water stress was due to reduced leaf area and a number of green leaves per stalk. Water stress had a greater effect on the expansive growth of lamina than its dry mass. Among different sugarcane varieties, water deficits reduced LAI and the biomass of sugarcane throughout the growing period. Inman-Bamber [36] observed that the specific leaf area (SLA) was lower in droughttreated plants as compared to control plants. da Silva & da Costa [37] has observed a significantly higher reduction in LAI under rainfed conditions than in irrigated conditions. Gomathi et al. [31] reported that the drought treatment caused an average reduction of 27.4 and 17.4% in leaf area and LAI, respectively in sugarcane. Varieties

Co 99,004 and Co 99,008 transpired less water and showed a relatively higher photosynthetic rate with significant improvement in growth attributes, viz., shoot leaf production and LAI. LAI showed significant variation among the genotypes and treatments indicating the sensitivity of these parameters to drought treatment. The genotypes Co 99,004, Co 99,012 and Co 99,006 recorded higher LAI of 3.53, 3.40 and 3.06, respectively even under drought conditions indicating their adaptability for leaf area production. Farooq et al. [38] reported a substantial reduction of LAI with increasing drought levels in a sugarcane cultivar.

It is well-established fact that the plant infrastructure is decided by the growth parameters such as, CGR, RGR and NAR. This concept not only involves the final crop yield and its components, but also probes into the physiological events that have occurred early in the growth stages causing variation in yield potential [39]. Singh & Singh [40] reported that 20 days and 40 days irrigation intervals in different sugarcane varieties caused significant loss in dry matter production *viz.,* RGR, NAR, and CGR during stress period when all other conditions were favorable for the remaining period of growth. Ramesh [41] evaluated four commercial sugarcane varieties (Co 8021, Co 419, Co 8208 and Co 6304) under three levels of drought stress (severe, moderate and control) during the formative phase (60–150 days after planting) and found a higher reduction in NAR, LAI, CGR especially under water-limited drought conditions. Farooq et al. [38] reported that NAR was lower at 80 and 60% irrigation coefficient as compared to 100% irrigation coefficient and variety NSG-59 showed higher NAR. Leaf area and cane length exhibited 37.3% and 26.53% reduction under drought conditions in comparison to the control [2].
