Abstract:
In order to compare the
effects of phosphate solubilizing bacteria as
biofertilizer and mineral phosphorous
application in optimal date of sowing with
delayed cropping date on canola (Brassica
napus L.) growth and productivity, a splitplot
experiment, using randomized complete
block design with three replications, was
conducted at Dashate-Naz Agronomy
Research Station, in 2014. Four levels of
bacterial inoculation (Pseudomonas putida,
Pseudomonas fluorescens, singly or in
combination) were applied as main plots
and five levels of mineral phosphorus (P)
application (0, 25, 50, 75, and 100 kg·ha-1 of
mineral phosphorous) were applied as sub
plots. Canola plant were sown at two dates
of sowing, one at optimal date of sowing
(30 Sept., 2014) and the other one month
later as delayed cropping (30 Oct., 2014).
The results obtained showed that effects of
bacterial inoculation on number of seeds per
pod, number of pods on plant, and seed
yield were significant at one percent
probability level at both sowing dates.
Moreover, rates of phosphate application
had significant effects on all traits at one
percent level. Comparing the means showed
that application of mineral P resulted in
substantial increase in seed yield. At
optimal date of sowing, it was shown that
while minimum seed yield obtained at
control treatment (1600 kg·ha-1), the
maximum (2980 kg·ha-1) obtained with
interaction effects of application of both
bacterial strains along with 75 kg·ha-1 mineral P, having no statistically difference
with that of P. fluorescens, along with 75
kg·ha-1 mineral P (2940 kg·ha-1). It was
shown that delayed cropping resulted in
decreasing canola growth which is reflected
in seed yield and yield components.
Minimum seed yield at control plot at first
date of sowing (1600 kg·ha-1) decreased to
740 kg·ha-1, in the second date of sowing,
showing 54 % decrease. The maximum seed
yield also decreased in delayed cropping,
from 2980 kg·ha-1 at 30 Sept., 2014, as
compared to 1074 kg·ha-1 at 30 Oct., 2014,
showing a 64% decrease. The results
obtained showed that an increase in P level,
eventually enhanced the seed yield. This
increasing trend continued until a threshold
level (75 kg·ha-1 of P), after which seed
yield showed a declining fashion.
