MSc

Studies on the "Effect of plant growth regulators on growth and
productivity in yard long bean (Vigna unguiculata var. sesquipedalis (L.)
Verdcourt)" was conducted at the Department of Olericulture, College of
Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur during rabi
(September, 2000 to January, 2001) and summer (February, 2001 to May, 2001)
seasons using the variety 'Lola'. Four plant growth regulators (NAA, 2,4-D,
PCPA and CCC) at three concentrations each, constituted twelve treatments
excluding water spray and non-treated control. The experiment was laid out in a
Randornised Block Design (RBD) with three replications. NAA (15, 30 and 45
pp m) was sprayed thrice at 30, 45 and 60 days after sowing (DAS) and CCC (300,
400 and 500 pp m) at 20 DAS in both rabi and summer seasons. During rabi season
2,4-D (2, 4 and 6 pp m) and PCPA (25, 50 and 75 ppm) were applied at 30, 45 and
60 DAS and during summer at 45 and 60 DAS.
NAA and CCC at lower concentrations (15 ppm and 300 ppm respectively)
were effective for the growth and productivity in both the seasons. In case of
vegetative characters, NAA at 15 ppm produced maximum vine length (6.58 m)
and CCC at 300 ppm produced maximum number of secondary branches (18.67).
CCC (300ppm) application resulted in early flowering (39.33 days) and harvest
(46 days) during rabi. NAA and CCC at lower concentrations were equally
effective for increasing the fruit set by reducing the flower and pod shedding in
both rabi and summer seasons.
Spraying of 2,4-D and PCPA at all concentrations resulted in vegetative
malformations like curling, cupping and strap shaped leaves without any leaflets,
long internodes, funnel shaped leaves with bushy and stunted appearance when








applied at 30, 45 and 60 DAS. This adversely affected the growth and productivity
of the crop during rabi. The perfomance of 2,4-D and PCPA treated plants were
better without any noticable vegetative malformations when applied at 45 DAS
during summer.
NAA at 15 ppm increased productivity of cowpea by 35.19 per cent
yielding 7.49 tonnes per hactare compared to 5.54 tonnes in control during rabi
season. During summer, the productivity of the crop was maximum (6.41 t ha")
in CCC 300 ppm which was due to more number of fruits per plot (561.95), length
of fruit (36.86 cm) and mean fruit weight (16.89 g). The crude protein content was
higher in all CCC treatments. Mosaic incidence was also less (4.55 %) in CCC
treated plants compared to control plants (24.55 %) during summer season.