The Effects of Genotype, Soil Type, Rate of Fertilizer, and Shade on Sugarcane Flowering Time.

The synchronization of flowering time for sugarcane clones is critical for the success of sugarcane breeding program. Two known factors that contribute to flowering time were photoperiod and physiological age of clone. Little research about genotype, shade, rate of fertilizer (N), and soil types (soil) effecting flowering time has been reported for sugarcane. The objectives of this study were to identify major factors and interactions among those factors that are responsible for the flowering time. Three varieties, CP xx-1143, CP xx-2390, and CP 89-2143, were selected to represent early, mediate, and late flowering in this study.  The three clones were plant in a split-split plot design with three replications in 2010 and 2011. AUFPC (Area under flowering progress curve) index was adapted to measure flowering progress. An analysis of variance (ANOVA) was conducted to evaluate the differences among four factors. A multiple comparison T-test by Fisher’s Least Significant Differences (LSD) was used to test the differences among AUFPC mean of each treatment within four factors. Highly significant differences were found for genotype in both years but for rate of fertilizer and soil type in 2011. The interaction of N x Soil consistently showed from year to year and genotype x N x Soil was detected in 2010 and the interactions of Genotype x N and N x Soil werepresented in 2011. The results from T test demonstrated the greatest difference for mean AUFPC index of each treatment within four factors was genotype ranging from 0.03 to 0.68, compared to 0.29 to 0.38, 0.31 to 0.38, and 0.34 to 0.36 for N, soil type, and shade, respectively. The results implied that genotype plays a major role in flowering time for sugarcane; therefore, extending crossing season in sugarcane breeding program is essential to manipulate the crosses by design.