THE IMPACT OF SEQUENTIAL APPLICATION OF PGR AND PGR+ NUTRIENT COMBINATION ON GROWTH, PHYSIOLOGICAL AND YIELD ATTRIBUTES OF SUGARCANE.

To study the impact of different PGR and PGR+ nutrient combinations on growth, physiological and yield attributes of sugarcane, three bud setts of variety, CoLk 94184 were primed with plant growth regulator (PGR), ethrel (@ 100 ppm) and nutrient, KCl (@0.2%) overnight and planted along with untreated control under field conditions in three replications at ICAR-IISR farm, Lucknow in spring season (2017-18). Planted sett buds were investigated for changes in reducing sugars content and SAI activity. Foliar application of ethrel and ethrel + nutrient mixture was performed in Set-I untreated control (no sett soaking) with T1-T7 treatments; T1 - No spray (Control), T2 - ethrel spray @100 ppm (Spray 1), T3 - ethrel (100 ppm) + ZnSO₄ (0.5%) (Spray 2) at 60DAP, T4 - Spray 1 + GA₃ spray @50 ppm (Spray 3), T5 - Spray 2 + GA₃ (50 ppm) + CaCl₂ (1%) (Spray 4) at 110 DAP, T6 - Spray 1 + Spray 3 + Kinetin @100ppm (spray 5), T7 - Spray 2 + Spray 4 + Kinetin (100 ppm) + MnCl₂ (0.1%) (Spray 6) at 175 DAP. In Set-II ethrel treated (Pre-soaked setts) with T8-T14 treatments and Set-III KCl treated (Pre-soaked setts) with T15-T21) treatments, same types of treatments were given as in Set I. After 25 days of foliar application, total shoot population, fresh and dry weight of different plant parts, chlorophyll contents, and nitrate reductase (NR) activity were determined. Juice quality attributes were recorded in cane juice in each month starting from November 2017 to February 2018 and cane yield after harvesting. Findings obtained indicated higher SAI activity and reducing sugar content in treated buds. Further foliar application of ethrel and ethrel + nutrient and at elongation stage, foliar application of GA₃ and GA₃ + nutrient showed increased shoot population, chlorophyll a, b and total contents, fresh and dry weight of different plant parts and NR activity in treated sets. At harvesting, number of milliable cane (NMC/plot) in most of the treatments were higher; highest was in T11, T5 was at par followed by T13, T14 and then T8. Cane yield observed maximum in T5 (111.6 t/ha), T14 was at par (111.1 t/ha) followed by T8 (107.0 t/ha), T12 (106.4 t/ha), T11 (105.0 t/ha) and minimum in T1 (83.2 t/ha). Similarly, highest cane height and girth were observed in T11 (275.3 cm) and T8 (2.14 cm) treatments, respectively. Highest increase in sucrose % juice, CCS% and °Brix were observed in T11 treatment, while lowest reducing sugars was obtained in T17 followed by T15 treatment. Results suggested beneficial impact of PGR and PGR+ nutrient combination application on growth, yield and juice quality attributes of sugarcane when applied sequentially in whole crop duration. [ABSTRACT FROM AUTHOR]