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Abstract
Potato stands 4th
after wheat, rice and maize among the major food crops in Pakistan.
It was grown on an area of 131.9 million hectare with 2622.3
thousands tons of production averaging 19.9 tons ha-1 during the
year 2007 which was very low as compared to the yields of leading
potato growing countries of the world. Potato is a short duration,
high yielding and exhaustive tuberous crop. Balanced use of
nutrients is essential for a sustainable productivity of crops.
Nitrogen and phosphorus fertilizer are being used while ignoring
potassium application which causes serious decrease in the status of
K in soils of potato growing areas because K has great importance in
improving quality and yield of potatoes. Potassium has a crucial
role in higher productivity of potato tubers because it plays an
important role in photosynthesis, regulation of opening and closing
of stomata, favors high energy status which helps in timely and
proper nutrients translocation and water uptake in plants. The
potato growers in Pakistan follow different practices and techniques
in different localities for higher yields in potatoes. Keeping in
view, the existing management practices of potato growers in
Pakistan, a research project of field studies comprising of four
experiments, was designed for the selection of best source of
potassium, time and application of fertilizer techniques, different
levels of potassium to determine the effects of K on some physio-morphological
features of the crop. A promising red potato cultivar Desiree” was
selected. The optimal recommended dose of potassium (125 kg ha-1)
was supplied at the time of planting. Data of different qualitative
and quantitative characteristics were collected under the Randomized
Complete Block Design with three replications and analyzed by using
standard statistical techniques.
The experiment#1 was conducted in order to assess the impact of
different organic and inorganic sources of potassium (i.e. FYM, SOP
and MOP) for the evaluation of the best with 10 different
combinations of treatments which were replicated thrice. The
parameter like total emergence %age, No. of aerial stems plant- 1,
specific gravity and tuber dry matter %age were found statistically
non-significant while, No. of leaves plant-1, Plant height, No. of
tuber plant-1, Tuber weight plant-1, Yield ha-1 TSS and tuber dry
weight plant-1, were observed significant and gave better in case of
T2 (SOP source). In some of the parameters like Tuber weight
plant-1, yieldha-1 and tuber dry weight plant-1, T4 (½ from SOP+ ½
from FYM) were found equally effective with T2 whereas, T0 (control)
performed worse.
The experiment #2 comprised of 9 treatments with 3 replications.This
experiment was undertaken to check the effects and proper time of
potassium application methods.The parameters of total emergence
%age, number of aerial stems plant-1 and number of tuber plant-1
were found statistically non-significant while, number of leaves
plant-1, plant height, number of tuber plant-1, tuber weight
plant-1, yield ha-1, TSS, specific gravity, tuber dry matter %age
and tuber dry weight plant-1 were found significant with the
supremacy of T2 ( Full dose of SOP at the time of planting through
placement method) with the conclusion that SOP was found superior to
the other potassium sources in most of the aspects of growth and
yield of potato crop.
For the assessment the best level of K in order to the maximum
growth and yield of potato, the experiment #3 was designed with 7
numbers of treatments and 3 replications. The parameters of total
emergence %age, plant height, number of tuber plant-1, tuber weight
plant-1, yield ha-1, TSS and tuber dry weight plant-1 were found
statistically significant while, number of aerial stems plant-1,
number of leaves plant-1, specific gravity and tuber dry matter %age
were observed significant with the supremacy of T3 (150 kg K2O ha-1)
which was found the best for most of the aspects of study. An
excessive dose of K2O up to 250 kg K2O ha-1 was found ineffective
for vegetative and yield characteristics while the under dosing up
to 100 kg K2O ha-1 was observed comparatively less effective.
The experiment #4 was conducted for convenience of different
physiomorphological and storage aspects of potato crop by applying
FYM, SOP and MOP with 6 combinations of treatments and was
replicated thrice. The data were collected on 5 fortnight intervals
with effect from 30 to 90 days after planting. The agronomic
parameters, like number of leaves, leaf area index, leaf area
duration, crop growth rate, relative growth rate, net assimilation
rate, stem length and diameter were observed significant for the
treatments and the years with the superiority of T4 ( ½ SOP + ½ FYM)
followed by T2( Full dose of SOP) while T0( control) was found at
the bottom.The physiological aspects such as chlorophyll contents,
net photosynthesis rate, intra cellular CO2 concentration,
transpiration rate, stomatal conductance and water use efficiency
were found statistically significant for the treatments and the
years with the best results from T4 ( ½ SOP + ½ FYM)and T2 (Full
dose from SOP). The storage behavior was studied by keeping tubers
at ambient and cold storage conditions.The results were gathered at
5 fortnight intervals with effect rom 30th days after storage. The
data for the weight loss %age, sprouting %age,
rotting % age, physiological disorders % age, starch contents % age,
protein contents %age, reducing sugars and vit.C showed significant
differences with the superiority of SOP alone or in combinations
with FYM as compared to the other treatments while T0 was observed
at the bottom. The cold storage conditions were found better as
compared to ambient conditions. For the physic-chemical
characteristics like starch %age, protein, reducing sugars and vit.C,
T2 (Full dose from SOP) was again found effective as compared to the
other variables of potassium applied for the study, in both
conditions of storage. |
