PhD

Three field experiments and one green house study were conducted at Cashew
Research Station (CRS), Madakkathara, Thrissur, Kerala during 1997 -99 with the
objective to study the response of graft raised cashew to varying levels of nutrient
regimes and to assess the variation in leaf nutrient status in relation to nutrient regimes
and to develop yield prediction model based on tissue nutrient status; to study the
varietal variation in tissue nutrient status of eighteen promising varieties in relation to
yield; to assess the effect of lime and Mg S04 on the growth and productivity of cashew
in late rite soils; to develop a nutritional strategy in the cashew nursery for the production
of healthy root stocks.
Exp. I Influence of nursery technique on growth of cashew root stocks
a) Effect of potting media and nutrient supplements
b) Effect of lime incorporation in potting media
A study was also carried out to standardize a nutrient management strategy in
the nursery to produce vigorous root stock. Three different potting media (soil, sand and
FYM in 1: 1: 1; soil and FYM in 1: 1; soil and sand in 1: 1 ratio) and four nutrient
supplements (control, 100 g N; 200 g N + 100 g PZ05; 200 g N, 100 g PZ05 and 200 g
KzO 100 kg-1 potting media) in a factorial combination. The potting media containing 1: 1
soil : FYM mixture supplemented with 200 g N, 100 g PZ05, 200 g KzO per 100 kg
potting media is best for producing good quality cashew seedlings.
Investigation conducted to study the effect of incorporation of lime in potting
media at different levels varying from 0 to 500 g 100 kg-1 potting media revealed that the
response of cashew seedlings to the application of lime was limited.

Exp. 11 Effect of soil nutrient regimes on leaf nutrient status and yield of graft
raised cashew
This study involving four nutrient reqirnes - namely, 375:165:375; 750:325:750;
1125:390:1125 and 1500:650:1500 g N, P20S and K20 tree-1 year" and an absolute
control was conducted for three years on graft raised cashew variety Madakkathara-1.
Flower production and yield characters were significantly influenced up to a level
of 750:325:750 g NPK tree-1 year" .The chlorophyll a and b was highest both at flushing
and flowering stages with the application of 750:325:750 g NPK tree-1 year". At pre-
flushing and pre-flowering stages, Nand K concentration in leaf, the total uptake of N
and K, the highest nut yield as well as kernel yield was highest with the application of
750:325:750 g NPK tree" year".
Exp. III Effect of soil application of lime and magnesium sulphate on growth and
productivity of graft raised cashew
Investigation was carried out on five year old cashew grafts of variety
Madakkathara-1, to study the effect of application of lime and MgS04 at four levels each
(0, 500, 1000 and 1500 g tree" year") in a factorial combination on growth and
productivity of cashew.
The results showed that primary factors regulating the productivity of cashew
was the number of flushes per unit area and application 500 g lime and 1500 g MgS04
has registered 85 per' cent reproductive flushes. Application of 1500 g lime and 1000 g
MgS04 increased bisexual flowers, nut panicle" and nut weight. Increase in the
contents of N, P and K was associated with decrease in the contents of Fe, Mn, Zn and
Cu, which explains the fact that these micronutrients restricted the uptake of primary
elements.

Exp. IV Varietal variation in leaf nutrient status and its relation with nut yield
Among the 18 varieties tested in the varietal evaluation trial, three varieties
namely V-5 and V-4 (Vengurla selections) and M-26/2 (Vridhachalam selection) were
found to be promising in terms of nut yield, the most important commercial criteria in
cashew. In most of the parameters related to yield, the above varieties were found
comparatively better. Photosynthetic efficiency measured in terms of leaf chlorophyll
content was also higher in these varieties. Leaf nutrient concentration (N and K) was
also comparatively high in the high yielders.