In India UP, Karnataka and Maharashtra are the three states that accounted for more than 80% of Indian sugar production [3]. AP stands 11^th position in area and production and 10^th position in productivity in the country [2]. Sugarcane is grown under soil moisture stress/drought conditions in sizeable areas under early planting (December – January) in North Coastal districts in addition to rainfed cane cultivation. Nearly 40-50% of cane cultivation of the North Coastal zone is under moisture-stress conditions/rainfed cane cultivation. The crop experiences moisture stress at all crop growth stages. Moisture stress affects germination, cane length, cane diameter, single cane weight, cane elongation, biomass production, NMC, and cane yields under early planted rainfed conditions [13], [14] [11]. The relative water content (RWC) of sugarcane leaves of susceptible varieties to drought is lower than the tolerance once [15]. An abiotic or biotic stress in the growing phase in the period of rapid growth, cane drastically reduces the yield as well as affects the potential

* Dr. Ch. Mukunda Rao, Principal Scientist (Crop Physiology), RARS, Anakapalle – 531 001, A.P

1 Dept. of Crop Physiology, 2. Dept. of Genetics and Plant Breeding 3. Dept. of  Agronomy 4. Dept. of Post harvest technology (Regional Agricultural Research Station (RARS), Anakapalle)

for regrowth and longevity of sugarcane crop [5]. The cane yields obtained are ranged from 40 – 45 t/ha under moisture stress conditions of Andhra Pradesh. SPAD/SCMR values, SOD values and carbon isotope discrimination values indices of moisture stress tolerance in field conditions [9]. In tolerant clones, high values of SPAD and other ancillary parameters with cane yield of sugarcane were recorded high under moisture stress conditions [16] [7]. Under drought management sugarcane variety also plays an important role along with other management practices to mitigate the yield loss to some extent [10].

         In A.P., sugarcane varieties 87A 298 and 2003V 46 are the leading varieties occupying a considerable area of sugarcane which were released nearly 15 years back. Now due to degeneration of existing good varieties, there is a dire need of ample number of new sugarcane varieties especially with drought tolerance and higher cane yield and quality. Abiotic stresses are common factors lowering yields of AP. Under these circumstances, this study was initiated with 15 pre-release sugarcane clones with an objective to identify sugarcane clones tolerance to moisture stress/drought during crop season especially of the formative stage of sugarcane which coincides with summer and maturity stage which coincides with the winter season.

MATERIAL AND METHODS

Fifteen promising pre-release clones were studied with 87A 298 as check variety under early planted moisture stress conditions at Regional Agricultural Research Station, Anakapalle during 2020-21, 2021-22, and 2022-23 for three years. The design adopted was RBD with 2 replications. Each clone was planted in six rows of eight meters in length with a spacing of 80 cms between rows. The date of planting was in the month of January 2020, 2021 and 2022. Moisture stress I₀ treatment was imposed by withholding irrigation from March, 15^th except two life irrigations at 10 DAP and 40 DAP till harvesting of sugarcane, where as check I₁ (Normal) treatment was imposed by need-based monthly one irrigation from planting to harvesting of cane. Trash mulching @ 3 t/ha was done at 3^rd day after planting. Soils are of light to medium texture with low to medium N and medium P and K nutrient status. Crop was raised by following all good management practices. Management of early shoot borer and white fly was carried out by spraying Monocrotophos @ 1.6ml/lt and biologically controlled using Trichocards. A fertilizer dose of 112 kg N + 100 kg P₂O₅ + 120 Kg K₂O/ha was adopted. Nitrogen was applied into two equal splits at 45 and 90 DAP, (and ×) P and K was applied as basal. Detrashing and spreading of dried leaves was carried out in between two rows to conserve soil moisture after the cessation of rains (November month). Data was recorded on cane yield, per-cent juice sucrose, ancillary data [6] and NMC at harvest, SCMR values at 120 DAP and leaf proline at 120 DAP were recorded by adopting standard procedures [4], duly following soil moisture data at the formative stage during summer months. Statistical analysis was carried out by methods given by [12].

RESULT AND DISCUSSION

         The analyzed data on cane yield, yield components and other quality parameters with ancillary day are given in Table 1, 2, 3 & Fig D. The results obtained are presented on character-wise. The weather parameters including soil moisture data was given for 2020-21, 2021-22, 2022-23 in Table A, B & C. The soil moisture was low in stress treatment when compared to irrigation treatment in the months of soil sampling. The rainfall pattern during the sugarcane crop season at RARS, Anakapalle (2020, 2021, 2022) was given in figures A, B, C emphasizing the stress period at March 15^th to June 15^th (formative stage) and October 15^th to January 15^th (Maturity stage).