Effect of Gibberellic Acid 4 and 7 and 6-Benzyl Adenine on Growth, Yield and Quality of Sugarcane in Kakamega County, Kenya
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Date
2020
Authors
Achola, Andrew Adodi
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Declining sugarcane productivity in Kenya has attracted a plethora of interventions such
as optimal fertilizer regimes, improved seedcane quality and use of plant growth
regulators (PGRs). Although application of PGRs in leading sugarcane producing
countries like China and India has registered success, sugarcane farmers in Kenya are yet
to exploit this technology. Globalization and liberation of world sugar industry now
subjects the local millers and farmers to stiff competition. The local sugar millers have
responded by seeking to adopt payment model based on yield and sucrose content. To
address this problem, a study was conducted to determine the effect of different levels of
gibberellic acid 4 and 7 and 6-benzyl adenine on growth, yield and sucrose content of
five selected sugarcane varieties (CO 421, KEN 83-737, D8484, CO 945 and EAK 73-
335). The study was carried out at the Butali Sugar Company Research and
Demonstration farm in Chegulo, Kakamega County-Kenya. The trial was laid out in a
Randomized Complete Block Design in 5 by 5 factorial arrangement. The treatments
consisted of gibberellic acid 4 and 7 and 6-benzyl adenine at 0 1, 2, 3 and 4 litres per
hectare and the five sugarcane varieties. All treatments were replicated three times. Data
on germination, tillering, height, girth, length of internodes and leaf number was collected
monthly for six months for two seasons. Data on yield was collected by harvesting all the
sugarcane from each plot at the 12th month after planting and recording the stalk biomass.
Pol% was was generated by extracting juice from 10 randomly selected stalks per plot to
obtain a homogenized, composite sample before adding lead sub-acetate clarifier and
measuring the filtrate using a polarimeter before multiplying the recorded value by the
corresponding pol factor. All the data was subjected to ANOVA using SAS 9.1 software;
and means separated using Tukey’s test (P≤0.05). Finally, cost-benefit analysis was
computed for all varieties under study. It was observed that use of gibberellic acid 4 and
7 and 6-benzyl adenine led to significant and or linear increasing growth, yield and quality
(sucrose content) of sugarcane. It was also observed that the varieties differed in their
response to application of the gibberellic acid 4 and 7 and 6-benzyl adenine. In yield,
D8484 grown with GA4+7 and 6-BA at 4 litres per hectare recorded the best performance
at 75.35 and 75.23 tons/ha in Seasons 1 and 2 respectively. EAK 73-335 recorded
superiority in sucrose accumulation with pol% of 14.70% and 14.69 % in seasons 1 and
2 respectively when treated with GA 4+7 and 6-BA at 4 litres per hectare. There was no
significant difference at 4 litres per hectare in all parameters under study. Application of
gibberellic acid 4 and 7 and 6-benzyl adenine increased growth, yield and quality of the
sugarcane varieties with D8484 recording the best overall performance and the highest
net positive benefit-cost ratio at 3.7. Gibberellic acid 4 and 7 and 6-benzyl adenine
increased yield by 11-22% and sucrose content by 3-6%. Therefore, it is recommended
that variety D8484 and EAK 73-335 be grown and gibberellic acid 4 and 7 and 6-benzyl
adenine at 3 litres per hectare be incorporated in the production of sugarcane in Kakamega
County and areas with similar agro ecological conditions. In addition, there is need for
evaluation of response of more cane varieties and in other agro ecologies. Further study
is recommended on performance of ratoon crop previously applied with gibberrellic acid
4 and 7 and 6-benzyl adenine.
Description
A Thesis Submitted in Partial Fulfillment of the
Requirements for the Master of Science (Agronomy) in the
School of Agriculture and Enterprise Development of
Kenyatta University
Keywords
Gibberellic Acid 4, 6-Benzyl Adenine, Quality of Sugarcane, Kakamega, Kenya, sugarcane productivity, plant growth regulators (PGRs)