Flowering Behavior of Sugarcane Genotypes under Artificial Photoperiod Impacted by Nitrogen, Phosphorus, and Potassium (NPK) Fertilization Rates

The experiment was conducted during 2021/2022 and 2022/2023 at the breeding station of the Sugar Crops Research Institute, Agriculture Research Center (ARC), Giza, Egypt (30° 0' N latitude, 31° 12' E longitude) to examine the response of ten sugarcane genotypes to NPK fertilizer application rates (600 , 900, 1000, and 1100 gram of NPK) under two photo-inductive cycles of treatments of constant 12.5- hours per day of 30-days and 60-days length followed by a declination of 30 seconds/day to 11 hour 30 min. A split spilt-plot design in a randomized complete block arrangement was used with two replications. Data on reproductive flowering characteristics (Pre-flag, flag leaf duration, tip emergence, and full emergence stages) were also gathered at the various sugarcane phases in addition to the total flowering percentage and pollen viability percentage. The genotypes under study had significantly varied flowering attributes at different times when fertilization was applied, with two continuous photo inductive cycles. Significant variations were seen in the percentages of flowering plants, pollen viability, and flowering features (per flag, flag leaf, tip, and full emergence stages) among the NPK application rates and genotype × NPK × constant inductive cycles interaction. Under inductive cycle treatments for 30 and 60 days, respectively, the percentage of flowering plants varied dramatically both inside and between NPK application rates. Additionally, compared to the optimal rate of 600 g, when NPK fertilization was applied later with increasing rates, there was a decrease in flowering behavior and an increase in the percentage of flowering.