PhD

An investigation entitled ‘Tillage and nutrition for productivity
enhancement in tannia (Xanthosoma sagittifolium (L.) Schott)’ was undertaken at
College of Agriculture, Vellayani to identify ideal tillage system for productivity
enhancement in tannia, to study the effect of soil conditioners and to compare the
effects of integrated and organic nutrition on growth, yield and quality of tannia
and to work out the economics of cultivation. The field experiments were
conducted in the Instructional Farm attached to College of Agriculture, Vellayani
from August 2014 to May 2015 and repeated during May 2015 to February 2016.
The field experiment was laid out in split plot design with 24 treatment
combinations and four replications. The main plot treatments consisted of four
tillage systems (l1- conventional tillage followed by pit system, l2- conventional
tillage followed by mound system, l3- deep tillage followed by pit system and
l4- deep tillage followed by mound system) and sub plot treatments were
combinations of two soil conditioners along with a control (s1- control, s2- coir
pith @ 500 g plant-1 and s3- rice husk @ 500 g plant-1) and two nutrient
management practices (n1- integrated nutrient management (INM) – FYM @
25 t ha-1 + 80:50:150 kg NPK ha-1 and n2- organic nutrition- FYM @ 37.5 t ha-1
+ wood ash @ 2 t ha-1).In the case of INM, half the quantity of FYM and full P
were applied as basal dose and remaining FYM and full N and K were applied in
three equal splits each at two, four and six months after planting along with
interculture and earthing up. For organic nutrition, 2/3rd quantity of FYM was
given as basal dose and remaining FYM and wood ash were given in three equal
splits each at two, four and six months after planting along with interculture and
earthing up. Dolomite @ 1 t ha-1 was applied uniformly to all plots at land
preparation.
Growth characters like plant height, leaf number plant-1and leaf area index
were improved by deep tillage followed by pit system of planting. Application of
coir pith as soil conditioner profoundly influenced growth characters. Organic
nutrition was found superior to INM in improving growth characters.
Yield components like cormel number plant-1, cormel and corm yield
plant-1 and cormel: corm ratio were significantly higher due to deep tillage
followed by pit system of planting. Application of coir pith as soil conditioner
registered significantly higher values of yield components. Organic nutrition
proved its superiority over INM in influencing the yield components.
Cormel yield was found to be significantly and positively correlated with
leaf area index at five months after planting, cormel number plant-1 and
cormel : corm ratio. Significantly higher cormel yield (5.15 t ha-1) and corm yield
(7.73 t ha-1) were obtained due to deep tillage followed by pit system. Deep tillage
resulted in 24 per cent increase in yield over conventional tillage and pit system of
planting registered 28 per cent increase in yield over mound system. Coirpith as
soil conditioner resulted in higher cormel yield of 4.51 t ha-1 (11 per cent increase
in yield over control) and corm yield of 6.99 t ha-1. Organic nutrition significantly
improved cormel yield (4.52 t ha-1 which was 12 per cent higher than due to INM)
and corm yield (7.07 t ha-1) compared to INM. Pooled analysis indicated that
interaction of deep tillage followed by pit system with coir pith as soil conditioner
and organic nutrition (l3s2n2) recorded the highest cormel yield (5.77 t ha-1) and
the same treatment, but with rice husk as soil conditioner (l3s3n2) recorded the
highest corm yield (8.3 t ha-1).
Deep tillage followed by pit system, application of coir pith as soil
conditioner and organic nutrition compared to INM recorded significantly higher
dry matter production and harvest index.
Quality characters of cormel like dry matter, starch and protein contents
were improved due to deep tillage followed by pit system among tillage systems,
application of coir pith as soil conditioner and organic nutrition compared to INM.
In general, a shelf life of one month for cormel was observed without any
microbial decay, sprouting and appreciable physiological loss in weight.
Higher uptake of N, P and K were noticed due to deep tillage followed by
pit system. Coir pith as soil conditioner proved its superiority in enhancing
nutrient uptake. Uptake of nutrients was significantly higher under organic
nutrition than under INM.
Tillage systems, soil conditioners and organic nutrition profoundly
influenced the physico-chemical properties of the soil after the experiment. Bulk
density was lowered and porosity and water holding capacity were improved due
to deep tillage, application of rice husk as soil conditioner and organic nutrition.
Correlation study revealed significant and negative correlation of yield with bulk
density and significant and positive correlation with porosity and water holding
capacity of the soil. Organic nutrition resulted in significantly higher status of
organic carbon and available N, P and K in the soil compared to INM.
Significantly higher net income and benefit cost ratio could be realized
due to deep tillage followed by pit system among tillage systems, application of
coir pith as soil conditioner and organic nutrition compared to INM. Considering
interaction effects, deep tillage followed by pit system without soil conditioner
under organic nutrition (l3s1n2) registered higher net income and benefit cost ratio.
It is evident from the present study that deep tillage to a depth of 30 cm
followed by pit system of planting is ideal for productivity enhancement in tannia.
Application of coir pith as soil conditioner and organic nutrition improved the
growth, yield and quality of tannia.Deep tillage followed by pit system and
organic nutrition (FYM @37.5 t ha-1 + wood ash @ 2 t ha-1) can be recommended
for economic production of tannia. Wherever coir pith or rice husk is available at
a cheaper rate, it can be applied as soil conditioner @ 500 g plant-1 for enhanced
productivity of tannia.