MSc

The project entitled "Floral induction and seed yield in amaranthus (Amaranthus
tricolor L.) as influenced by plant growth regulators" was carried out at the Department
of Vegetable Science, College of Agriculture, Vellayani, during 2020–2022, to study
the effect of different plant growth regulators on floral induction in the amaranthus
variety KAU Vaika, a short day cultivar, during non-inductive period, for seed
production.
The experiment was laid out in split plot design with three replications.
Treatments consisted of three foliar spray intervals (10 days after transplanting, 20 days
after transplanting, and 30 days after transplanting) in the main plot and four growth
regulators in two different concentrations consisting of eight treatments (BA at 50 and
100 ppm, GA3 at 50 and 100 ppm, TIBA at 100 and 200 ppm and Triacontanol at 50
and 100 ppm) in the subplot. Observations on vegetative, flowering, yield and seed
quality characters were recorded.
Foliar spray application interval at 10 days after transplanting resulted in the
highest growth characters in amaranthus, such as stem girth (6.40 cm), internodal length
(5.16 cm) and number of braches per plant (11.44) whereas at 20 days after
transplanting the total leaf weight (493.52 g) and total stem weight (334.10 g) were
highest. The foliar spray application interval at 20 days after transplanting resulted in
the earliest days to first flowering (114.72 days), earliest seed maturity (161.07 days),
and longest terminal panicle (24.92 cm). The yield characters like seed yield per plant
of 6.65 g was highest for foliar spray at 30 days after transplanting. Significant
difference could not be recorded in main plot treatments for growth characters like plant
height, fresh yield, leaf to stem ratio, leaf node to first inflorescence and height at first
flowering and seed quality characters like seed recovery percent, percent of chaffy
seeds, percent of bold seeds, 1000 seed weight and germination percent except for the
chaffy weight per plant (30.77 g), which was lowest for foliar spray at 10 days after
transplanting.
The highest plant height (86.27 cm), internodal length (6.44 cm) and stem
weight (384.09 g) were recorded in plants treated with GA3 at 50 ppm, while the longest
terminal panicle (28.09 cm) was recorded with the application of GA3 at 100 ppm.
Plants treated with BA at 50 ppm and 100 ppm recorded the highest leaf weight (533.61
g) and stem girth (6.84 cm), respectively. The highest number of branches per plant
(13.78), earliest emergence of the first flower (70.57 days) and earliest seed maturity
(116.68 days) were recorded with the application of TIBA at 100 ppm. Yield characters
like yield per plant (982.26 g) were highest for plants treated with BA at 100 ppm, while
the highest seed yield per plant (8.91 g) and lowest chaffy weight per plant (34.41 g)
were recorded for the foliar spray treatment of triacontanol at 50 ppm.
On analysing the interaction between foliar spray application interval and
concentrations of growth regulators, the highest growth characters were observed on
plants treated with BA or GA3, 10 days after transplanting. Growth characters like
internodal length and plant height were observed the highest with the application of
GA3 at 50 ppm and 100 ppm respectively at 10 days after transplanting, while the
longest terminal panicle (29.50 cm) was recorded for GA3 at 100 ppm at 30 days after
transplanting. The highest stem girth of 8.44 cm was recorded for BA 100 ppm, 10 days
after transplanting whereas the highest leaf weight of 693.30 g was recorded for BA
100 ppm, 20 days after transplanting. TIBA at 100 ppm, 20 days after transplanting
recorded the earliest flowering (52.60 days) and seed maturity (97.94 days) while TIBA
100 ppm, 10 days after transplanting recorded the highest number of branches per plant
(17.60). Yield characters like yield per plant (1115.22 g) was recorded the highest for
BA 100 ppm, 20 days after transplanting while seed yield per plant (10.54 g) was the
highest for triacontanol 50 ppm, 30 days after transplanting. Significant interaction
could not be observed for seed quality characters except for the chaffy weight per plant
(28.60 g), which was the lowest for TIBA 200 ppm, 10 days after transplanting.
The results of this experiment suggested that tri-iodobenzoic acid (TIBA),
gibberellic acid (GA3) and triacontanol have the capacity to trigger off-season flowering
in the amaranthus variety KAU Vaika. Application of TIBA and GA3 at 100 ppm, 20
days after transplanting could potentially cause early flowering, whereas the application
of Triacontanol at 50 ppm, 30 days after transplanting resulted in the highest seed yield
per plant.