PhD

Two field experiments and one observational trial were conducted in
the Instructional Farm, College of Agriculture, Vellayani during 1992 and
1993 to study the effect of drip irrigation and application of N and K
fertilizers on the growth and yield of cucumber.
In the preliminary observation trial (Experiment I a) three levels of
drip irrigation, (2, 3 and 4 I plant-1 day-1) four timings of irrigation (1, 2, 3
and 4 hours) and two number of drippers per plant (1 and 2 dripper plant-1)
were evaluated and based on the results of this experiment, the number of
drippers per plant and duration of drip irrigation was standardised.
Experiment 1 b was conducted to standardise the method of application
of fertilizers in Experiment 2 and 3 for which cucumber plants raised under
different levels of drip irrigation (2, 3 and 4 I plant-1 day-1). This was
conducted during April 1992.
The results of these experiments indicated the duration for drip
irrigation as 3 hours per day and one number of dripper per plant to be the
best. The spread and depth of root system of cucumber plants raised under
drip irrigation pointed out that the fertilizers as a ring around the base of
the plant at a distance of 20 cm will be within the root zone of the plant.

The experiments 2 and 3 were laid out in the field with three levels
of drip irrigation (2, 3, and 4 I plant-1 day-1), three levels of nitrogen (35,
70 and 105 kg ha-1) with three levels of potassium (25, 50 and 75 kg ha-1)
with three drip irrigation controls (2, 3 and 4 I plant-1 day-1) and farmer's
practice. The yield of cucumber was highest at the drip irrigation level of
31 planr-1 day-1. Irrigation at this level favourably influenced the vegetative
characters, yield attributes and yield. But root dry matter was not influenced
by the different drip irrigation level while the root spread and root depth
were highest at the drip irrigation level of 41 plant-1 day-1.
When different levels of nitrogen applied were observed, the
vegetative characters yield attributes and yield were found to be favourably
influenced at 70 kg N ha-1. The root spread of cucumber was highest at the
highest level of N applied (l05 kg ha-1).
Potassium at 50 kg ha-1 produced the highest yield due to its
favourable influence on the vegetative and yield characters. There was no
influence of potassium on my of the root characters studied.
The soil moisture status was highest up to 30 cm depth in all drip
irrigated treatments while in pot watered plots, the soil moisture was higher
in the lower layers below 30 cm.
The field water use efficiency was highest at the drip irrigation level
of 3 I plant-1 day-1, 70 kg nitrogen ha-1 and 50 kg potassium ha-1.

The nitrogen, phosphorus and potassium uptake by the plants and fruits were highest at the drip irrigation level of 31 plant day I, 70 kg N
ha-I and 50 kg K ha-I.
The physical optium levels of drip irrigation was 31 plant -1 day -1, 93 kg N ha-1 and 65 kg K ha-1 in the first season. When another crop is
repeatedly grown in the same field, the Nand K levels can be reduced to 75
kg ha-1 and 60. kg ha-1 but drip irrigation is required at the rate of 31
plant-1 day-1. This resulted in higher benefit cost ratio of 2.83 and internal
rate of returns of 23%. The payback period of this project worked out to
1.13 years.