Optimizing Crop Nutrition

Research findings
I Effect of potassium nutrition detrimental influence such that the greater
on growth, yield and quality of the K supply, the lesser was the stem
girth. This negative effect of K might
papaya possibly have been associated with the
high availability of N in the soil as excess
This report is based on the IPI - Tamil ‘N’ is known to decrease trunk diameter
N a d u A g r ic u l t u r a l U n i v e r s i t y , and also plant height at the flowering
Horticultural College & Research phase.
Institute project conducted in The continuous production of
Coimbatore, Periyakulam, Tamil Nadu, vegetative growth, flowering and
India. fruiting is a characteristic of Papaya so
that for papaya plants a high number of
leaves as well as a high leaf surface area
Potassium Nutrition of Papaya are important criteria in assessment of
The effect of potash fertilizer on the plant vigour. In this investigation, leaf
growth, yield and quality of papaya number was significantly increased by
fruits (cultivars Co-2 and Co-7) and K nutrition at two locations while the
latex (cultivar Co-2) has been same was true for leaf area only at one Latex tapping in Tamil Nadu. Photo by
investigated by Kumar et al. The study site. A high number of leaves and V. Nosov.
was carried out during 2004-05 in India in leaves with a high surface area enhance
Tamil Nadu using four locations in the production of photosynthates and
farmers’ fields. Four treatments with the synthesis of large quantities of 7, maximum fruit weight was observed
increasing levels of potash were applied: metabolites during growth and with 450 g K2O/plant/year, this variation
300:300:0; 300:300:150; 300:300:300 development. in response to K being attributed to
and 300:300:450 g N:P2O5:K2O/plant/ varietal difference. With an increase in K
year. rates up to K150-300, there was also a
Fruit growth and quality corresponding increase in the number of
fruits per plant at three of the locations,
Fruit weight of Papaya, which is a very
General effects on growth important economic character as far as although the effect was non-significant.
Tree growth parameters were assessed at marketing is concerned, was Fruit yield per plant as well as fruit yield
the first flowering phase, a critical one significantly influenced by K nutrition per hectare was significantly influenced
influencing the yield of papaya. Stem at all four locations. In general, an by K nutrition as revealed in the findings
girth was not affected significantly by K increase in K supply was accompanied from three sites. The general trend was
nutrition at three of the four locations, but by an increase in fruit weight up to K300 that fruit yield rose with the increased
at the other, K exerted a significant (Fig. 1). However, with the variety Co- rate of K application up to K300 and then
declined (Fig. 1). The exception, the Co-
7 variety responded to K fertilization up
2.0 160 to highest rate of application. These
Fruit weight findings have been interpreted that
Fruit yield
fertilization with K not only resulted in a
1.8 higher uptake of K but also increased the
140
availability of other nutrients in the soil,
Fruit weight (kg)

Fruit yield (kg)

1.6
leading to optimum vegetative growth,
enhanced uptake of nutrients, with the
120 promotion of photoassimilation and
1.4 translocation of assimilates from source
to sink, the result of which was reflected
100 by increased fruit yields.
1.2 K nutrition significantly affected pulp
thickness of papaya fruits in all the
1.0 80 locations (the maximum being with K300
in three sites and with K450 in one
0 150 300 450 location). This increase in pulp thickness
may be related to the role of K in
K2O (g/plant/year)
influencing the developing fruit which
acts as a stronger sink for K than for other
Fig. 1. Effect of K application on fruit weight and fruit yield per plant in papaya
(average for four locations). nutrients. It may also relate, as discussed

e-ifc No. 11, March 2007 2

Research findings
earlier, to the greater number of leaves
with a higher surface area that are
produced at higher levels of K nutrition,
which enable efficient transfer of K
from source to sink, in the development
of fruit with thicker flesh.
The sweetness of papaya, mainly
assessed by TSS (total soluble solids)
content, was found to be significantly
influenced by K. At all the locations, an
increase in the level of K application
resulted in a substantial increase in TSS
content. Potassium is known to promote N750P750 + K375 + K750 + K1125
sugar translocation in plants, thus its
application increased the sugar content
as well as TSS in the papaya fruit.
Potassium effect on size of fruit and yield of papaya. IPI-TNAU project in
Acidity is another important fruit
Vadipatti, Theni district, Tamil Nadu, India. The pictures and more are also
quality trait and should be at its available on IPI’s K Gallery (http://www.ipipotash.org/k-center/detail.php?
minimum value during ripening. At i=11). Photo by V. Nosov.
three locations, the acidity content
significantly decreased with increase in
K supply. K2O, Total latex yield
TSS of the latex (°Brix)
g/plant/year (kg/plot*)
A B A B
Latex yield and quality 0 181.23 32.00 16.70 ± 0.07 15.84 ± 0.11
No definite trend was observed on the 150 181.00 36.60 16.83 ± 0.04 15.76 ± 0.10
effect of K application on latex yield, as 300 155.22 35.00 16.91 ± 0.08 16.62 ± 0.10
recorded at the two sites investigated
450 137.40 34.10 17.00 ± 0.06 16.80 ± 0.10
(Table 1). This lack of response may
possibly have been due to the inherent
problems at field level in tapping the * 1,000 sq.m; A - Chandrapuram, B - Thondamuthur.
latex at fixed intervals. On the other
hand, however, the quality of latex Table 1. Effect of potassium application on the latex yield and its
quality in papaya.
assessed in terms of increased quantity
of TSS was raised by increased potash
fertilization as revealed in both
locations. This finding is of particular
interest since TSS content is an
important quality criterion by which the
latex procuring industries make
payments to growers. Additionally this
work appears to be the first recorded
evidence of a positive effect of K on the
quality of papaya latex.

Reference
Kumar, N., Meenakshi, N., Suresh, J.
and Nosov, V., 2006. Effect of
-K +K
potassium nutrition on growth, yield
and quality of papaya (Carica papaya
L.). Indian Journal of Fertilizers, 2 (4):
43-47. Go to IPI web site. N-P2O5-K2O = 750-750-0 N-P2O5-K2O = 750-750-750

Effect of potassium on number of and size of papaya fruit. Photo by V. Nosov.

e-ifc No. 11, March 2007 3