The investigation embodies the results of two
comprehensive multi- factor experiments, coupled with
observation plots ?carried out at the Bo &hall
Experimental Farm during the years 1946 and 1947 to
study the optimal levels of the diverse factors and
their optimal relations in the potato (var. Gladstone).
Detailed periodic growth observations were taken on
the selected treatments.The sprouts from small seed emerged later, were
fewer in number, had smaller reserves as well as the
assimilable sugars per sprout, and had slower early
development.The percentage rate of depletion of food material
from the mother tuber was not much affected by seed
size. About 10 -150 of the total food store was enough
to bring the sprouts near ground level with good root
ramification.uch higher demands on the mother tuber
were made during expansion of leaf primordia, when the
assimilation rate of the young leaves was surprisingly
low or negative. LoncurrentlyIthe sugar content of the
mother tubers increased.More than 50% of the original dry matter was
present in the old tubers after sprout establishment and
this continued to be used by the sprouts apparently for
laying down stolons and tuber initials till it fell
down to 20 -25%. A larger absolute surplus in the large
seed made for an earlier and greater tuber set at points
assured by more sprouts.fewer sprouts and tuber initials in case of small
seed, usurped smaller proportion of the assimilates
giving the plants a chance to recoup in vegetative
vigour. The leaf- weight -ratio as well as net assimilation
rate was consistently higher in the plants
from small seed. Axillary development below and the
expansion of leaves above constituted the compensatory
echanism in growth, in case of the small seed.
The size of new potatoes or the proportion of
ware in the produce rose as the seed size decreased,
due to higher shoot/tuber number ratio.In the wet year, the plants from small seed outgrew those from large seed but the compensation
(through improvement in tuber size) was inadequate to
offset in yield the depression through tuber number.In the dry year, the potential crop set by
large seed was not all carried into sizeable potatoes
for want of water so that the small seed produced about
as much yield as the large.The effects of spacing on the early growth, later
development, tuber size, tuber number and the gross
yields in the dry and the wet year were analogous to
those of seed size. A unit change in the level of
spacing, however, produced larger effect on the crop
characters than that of seed size.Closer spacing then 16" was risky if adopted
with large seed but was normally a profitable
proposition
if used with the small, medium or the
cut large seed in seed -producing areas.Closer spacing then 16" was risky if adopted
with large seed but was normally a profitable
proposition if used with the small, medium or the
cut large seed in seed -producing areas.A delay in planting caused a delay in emergence
by 1/3 - 1/2 the interval between plantings, and
raised the sprout number slightly.Late plantings had longer internodes, higher
leaf weight. ratio, greater succulence and higher relative growth rate,so that they excelled finally the
early planting in vegetative growth and flowering but
were inferior in tuber yields in either of the two
years.The superiority of early planting was enhanced
by close spacing, wet summer or nitrogen application.Nitrogen stimulated all phases of plant
activity, viz.,meristematic activity, extension growth,
ifferentiation, and storage. It increased leaf-weight ratio sufficiently to maintain higher relative
growth rate despite lower net assimilation rate
consequent upon shading.Nitrogen did not influence sprout establishment,
tended to increase the potential tuber set and raised
the tuber size or the ware proportion.Nitrogen was the most potent factor for yield
despite a basal dressing of organic manure and the dry
keather in 1947. The double dressing was much less
effective per unit N, and proved a luxury dose.The response to nitrogen declined with advancing
planting date, increasing seed size or rising basal
yield. It was not influenced by variation in soil
texture (within limits) and was definitely enhanced
by muriate of potash.The muriate of potash did not influence
meristematic activity, increased extension growth and
the water content of the plants and the tubers. she
effect on growth and yield was masked in the absence
of nitrogen, but improved with successive increments
of nitrogen.The results are discussed agrophysiologically
and the statistical aspects of the designs employed
are (Asserted
