PhD

The investigation entitled “Standardization of agrotechniques for precision
farming in watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai]” was carried
out at the Department of Olericulture, College of Agriculture, Vellayani, during the
period 2014-2016, to identify small fruited varieties / hybrids of watermelon with
high yield and quality and to standardize the agrotechniques for precision farming in
watermelon. The investigation comprised of two separate experiments.
The first experiment on ‘Evaluation of varieties / hybrids of watermelon’ was
undertaken from December 2014 to April 2015. The experimental material consisted
of 20 watermelon accessions, including three varieties and 17 hybrids. The
experiment was laid out in RBD with two replications. The analysis of variance
revealed highly significant differences among the twenty accessions for all the
characters studied. The highest yield plant-1 was recorded in the hybrid IB-23 (14.17
kg) followed by IB-20 and Saraswati, while the highest fruits plant-1, high TSS and
earliness in flowering as well as harvest was observed in the hybrid Prachi. The
variety Arka Muthu registered the lowest vine length of 1.20 m. High and moderate
phenotypic and genotypic coefficients of variation (PCV and GCV) were noticed for
most of the yield contributing characters. High estimates of heritability coupled with
high to moderate genetic advance as per cent of mean was recorded for all the yield
components, indicating additive gene action.
Yield had positive and significant correlation with the yield contributing
characters such as fruit equatorial diameter, fruit polar diameter, fruits plant-1, fruit
weight and seeds fruit-1. Path analysis revealed that fruit weight had the highest
positive direct effect on yield plant-1 followed by fruits plant-1. Fusarium wilt was the
major disease observed in few accessions during the study. Sensory evaluation
revealed the superiority of the hybrid Prachi over other accessions.
The second experiment on ‘Standardization of agrotechniques for precision
farming under rain shelter and open condition’ was conducted simultaneously under
rain shelter and open condition, from December 2015 to April 2016, using the best
hybrid Prachi. It was conducted in factorial RBD with twelve treatments and two
controls, with two replications. The treatments were three levels fertilizer viz., F1 -
75% of recommended dose (RD) (52.5: 37.5: 90 kg NPK ha-1), F2
-
100% of RD
(70: 50: 120 kg NPK ha-1) and F3 - 125% of RD (87.5 : 62.5: 150 kg NPK ha-1);
irrigation at two levels ie., I1- 80% Epan and I2 - 60% Epan; and two levels of
training viz., T1- nipping to one vine and T2 - nipping to two vines. Vines were
trained vertically under rain shelter and horizontally in open cultivation. The two
controls were, Control 1- Ad hoc recommendation for precision farming (70: 50: 120
kg NPK ha-1) with irrigation at 100% Epan and Control 2 - KAU Package of
Practices recommendations (POP).
Fertilizer levels had significant influence on flowering and yield attributes of
watermelon. The treatment F2 registered highest yield plant-1 both under rain shelter
and open condition, and was on par with F1 under rain shelter. The effect of
irrigation on vine length, fruit equatorial diameter, polar diameter and ascorbic acid
content was also significant under both conditions. The irrigation level I1 recorded
the highest yield plant-1 under rain shelter (11.10 kg) and open (8.42 kg). Training to
two vines significantly improved fruits plant-1 and yield plant-1 under rain shelter
while training had no significant influence under open condition. The water
requirement was 272.27 mm (I1) and 179.63 mm (I2) under rain shelter and 239.79
mm (I1) and 184.02 mm (I2) in open condition. Compared to conventional surface
irrigation, drip irrigation registered higher water use efficiency at both levels of
irrigation.
Pooled analysis also revealed that yield plant-1 was the highest in fertilizer
level F2, irrigation level I1 and training level T2. Among the growing conditions, rain
shelter recorded the highest number of fruits plant-1 (5.49), yield plant-1 (10.05 kg)
and maximum days to final harvest (115.53 DAT). Interaction effect of rain shelter
with training to two main vines recorded the highest fruits plant-1 (6.08) and yield
plant-1 (10.73 kg). Among the controls, Ad hoc recommendation for precision
farming was significantly superior to KAU POP recommendation.
The present study revealed the superiority of fertilizer dose 70: 50: 120 kg
NPK ha-1 (F2) and daily irrigation at 80 per cent Epan (I1) for watermelon under rain
shelter and open condition for yield and quality. Training to two vines could be
recommended for higher production under rain shelter. The hybrids Prachi,
Saraswati and Simran producing fruits having high TSS, small size and more number
of fruits were found promising under South Kerala condition.