MSc

The investigation entitled “Standardisation of nursery techniques through
field validation in minisett cassava (Manihot esculenta Crantz.)” which consisted
of a nursery experiment (April 2017 to June 2017) and a field experiment (April
2017 to January 2018) was conducted at College of Agriculture, Vellayani,
Thiruvananthapuram. The objectives were to standardise the cassava minisett
nursery technique by validating its field performance in comparison with normal
sett planting and to work out the economics of cultivation.
The nursery experiment was conducted in the Instructional Farm, College
of Agriculture, Vellayani. Minisetts of cassava, var. Vellayani Hraswa were
raised in protrays (50 cavity) with six treatment combinations in eight replications
as Completely Randomised Design. The treatments comprised two types of
minisett cuttings (m1- two node cutting and m2 - three node cutting) and three
types of potting media (p1 - normal top soil, p2 - normal top soil and coir pith
compost in 1:1 ratio and p3 - coir pith compost and vermi compost in 3:1 ratio).
The field experiment was laid out in the Instructional Farm, Vellayani with 18
treatment combinations replicated thrice in Randomised Complete Block Design
with the two types of minisett cuttings (m1 and m2) and three types of potting
media (p1, p2 and p3) tried in the nursery and three different time of transplanting
of minisetts to the main field ie. t1 - 3 WAP (weeks after planting), t2 - 4 WAP and
t3 - 5 WAP as treatments and normal sett planting as control. The minisetts and
normal setts were planted at a spacing of 90 cm x 90 cm.
The results of the nursery experiment revealed that the three node cutting
(m2) recorded significantly higher seedling sprouting (92.26 per cent), shoot
length (7.26, 9.62 and 11.10 cm), shoot biomass (4.08, 4.63 and 5.06 g seedling-1),
root length (8.09, 12.40 and 16.04 cm) and root biomass (0.46, 0.73 and 0.85 g
seedling-1) at 3 WAP, 4 WAP and 5 WAP respectively when compared to the two
node cutting (m1). The potting medium p3 recorded significantly higher shoot
length, shoot biomass seedling-1and root biomass seedling-1 at 3 WAP, 4 WAP
and 5 WAP and had significantly higher root length at 3 WAP and 4 WAP than
other potting media. The results on M x P interaction indicated that when three
node cuttings were raised in potting medium p3 (m2p3), the highest shoot length,
shoot biomass seedling-1and root biomass seedling-1 were recorded at 3 WAP
while it recorded the highest root length at 3 WAP and 4 WAP .
Growth and growth attributes viz., seedling establishment, plant height,
stem girth and number of functional leaves plant-1 at monthly interval and the leaf
area index at 3 MAP (months after planting) were significantly higher for the
three node minisett cuttings transplanted at an age of three weeks from nursery
than two noded minisetts transplanted at an age of four or five weeks. The
seedlings raised in potting medium containing coir pith compost and vermi
compost in 3:1 ratio (p3) produced significantly taller plants at all stages of
observation except 4 MAP besides significantly higher stem girth at 1MAP (1.73
cm), number of functional leaves plant-1 at all stages of observation and leaf area
index at 3 MAP (2.56).
The study revealed that the three node cutting (m2) was significantly
superior in terms of yield attributes and yield viz., length of tuber (45.99 cm), girth
of tuber (23.92 cm), mean weight of tuber (668.18 g), tuber yield plant-1 (3.90 kg),
tuber yield (39.25 t ha-1), top yield (13.86 t ha-1) and total dry matter production
(13.76 t ha-1). The potting media p3 produced significantly higher tuber yield
plant-1 (3.91 kg), tuber yield ha-1 (37.92 t), top yield (13.24 t ha-1) and total dry
matter production (13.82 t ha-1). Cassava minisetts transplanted at 3 WAP was
significantly superior with respect to yield attributes and yield.
Three node
cuttings raised in potting medium containing coir pith compost and vermi
compost in 3:1 ratio, transplanted at 3 WAP (m2p3t1) recorded significantly
higher mean weight of tuber (867.15 g), tuber yield ha-1(44.83 t), top yield (15.75
t ha-1), net income (₹ 6,92,267 ha-1) and benefit cost ratio (4.39). The uptake of
nitrogen and phosphorus were higher with m2 (three node cutting) ,while the
uptake of phosphorus alone was higher with p3 and uptake of nitrogen,
phosphorus and potassium was found to be higher with t1 (transplanted at 3
WAP). Comparing minisetts with normal sett planting (control), the former was
found to be superior in seedling establishment, plant height at all stages of
observation, leaf area index at 3 MAP, percentage of productive roots, length and
mean weight of tuber, tuber yield plant-1, tuber yield ha-1, top yield ha-1, total dry
matter production ha-1 and economics of cultivation.
The results of the study indicated that raising three noded minisett cassava
cuttings in potting medium containing coir pith compost and vermi compost in 3:1
ratio in the nursery
followed by transplanting at 3 WAP was found to be
economically and technically viable nursery technique for getting higher yield and
income from cassava cultivation compared to the conventional practice of
planting normal setts directly in the main field