Doi Asaph T. Guinanao (February 2009)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
Calcium carbide is the most widely used pineapple floral inducer in the Philippines. Calcium carbide mixed with water produces acetylene, the substance that induces flowering in plants. Researchers recommend the night-time application of flowering inducers because the lower temperatures increase the level of free auxin in the plant, leading to flowering. Also, pineapple exhibits stomata opening predominantly at night, and it is important that the stomata remain open four to six hour after the application of inducers. Thus, theoretically, lower temperatures plus optimum stomata opening will lead to better flowering efficiency. However, this has not been verified in field experiments; and in local practice, calcium carbide is mainly applied during daytime hours. Thus this study compared the percent flowering and fruit quality of Ananas comosus var. Formosa induced with calcium carbide during daytime and nighttime.
Four hundred pineapple plants in Hda. Sandra, Brgy. Bato, Negros Occidental were induced. Two hundred pineapples were induced at 10:25 am and another 200 pineapples were induced at 7 pm. After 4-7weeks, percent flowering was determined. Fruit quality was measured at harvest in terms of total soluble solids (TSS), total titrable acidity (TTA) and ascorbic acid content (AAC).
The mean percent flowering of was 95.00 ± 4.16% and 100.00 ± 0.00% for daytime and night- time induced plants, respectively. For daytime induced plants mean TSS, TTA and AAC were 15.68 brix, mg/mL and 10.572 mg/mL, respectively. For night-time induced plants mean TSS, TTA, and AAC 5.54 were 16.38 brix, 6.18 mg/mL and 0.462 mg/mL, respectively.
Mann-Whitney test showed that the percent flowering of pineapple plants induced during daytime is significantly higher than that c of pineapple plants induced during night-time (Z -1.984, p=0.047). However, independent t-test showed that there is no significant difference in the TSS (t = -1.397, p = 0.212), TTA (t=-1.738, p = 0.133) and AAC (t = 0.928, p = 0.855) between the two groups.
Night-time induction of pineapples led to more fruit harvest compared with daytime induction. However, it did not pose advantages in terms of fruit quality. This information will be of interest to farmers who wish to maximize pineapple production.