MSc.

Yard long bean is an important leguminous vegetable crop cultivated in Kerala. It is a
highly relished vegetable crop which can be cultivated throughout the year. However, weather
and climate are considered to be the most limiting factors in crop production. Since weather
conditions experienced by a crop play a major role in its growth and yield, the study of the
influence of weather on crop is very much important.
The present investigation on “Crop weather relationship of Yard long bean (Vigna
unguiculata subsp. sesquipedalis (L.) Walp) was carried out in the Department of Agricultural
Meteorology, College of Horticulture, Vellanikkara during 2013-2014 to determine the crop
weather relationship and to study the effect of date of sowing on the growth and yield of yard
long bean. The experiment was laid out in randomized block design with three replications at
Instructional farm, Vellanikkara from September 2013 to August 2014. The treatment comprises
of twelve dates of sowing at monthly intervals from September 2013 to August 2014. Yard long
bean variety lola was used for the experiment.
The different growth and yield characters like plant height, biomass, number of pods per
plant, number of seeds per pod, hundred seed weight, length of pod, pod yield per plot, pod yield
per plant and duration of different growth phases were recorded along with monitoring of major
pests and diseases. The daily weather parameters like maximum and minimum temperature,
forenoon and afternoon relative humidity, forenoon and afternoon vapour pressure, rainfall and
rainy days, bright sunshine hours, evaporation, wind speed and soil temperature were also
recorded.
The maximum temperature was found highest in February 2014 sowing and was recorded
lowest in July 2014 sowing whereas the highest minimum temperature was recorded in March
and April 2014 sowing. The crops sown during December 2013 and January 2014 received no
rainfall and those sown during June 2014 received the maximum rainfall. The bright sunshine
hours was recorded more in December 2013 sowing and was low in June 2014 sowing. Plant
height, biomass, phenological stages, yield and yield attributes were highly variable among the
different sowing dates. The March 2014 sown crops took more number of days to attain 50%
flowering followed by February 2014 sown crops. The crop duration was also observed more for
March sown crops which was on par with December 2014 sown crops. Yield and yield attributes
were influenced by various weather parameters experienced during the different crop growth
stages. Pod yield was highest from September and October 2013 sown crops and lowest from
May and July 2014 sown crops. Yield attributes such as number of pods per plant, number of
seeds, length of pods and hundred seed weight were also recorded more in September and
October 2014 sown crops. Pests such as aphids, pod borer, pod bug and diseases such as mosaic,
rust and anthracnose were observed in the crop during the study.
To determine the critical weather elements affecting the crop growth, correlation analysis
was done and it was found that maximum temperature, diurnal temperature range, soil
temperature at 10cm depth, wind speed and bright sunshine hours exhibited positive influence on
the pod yield, whereas increase in minimum temperature, growing degree days, relative
humidity, vapour pressure, rainfall and rainy days negatively influenced the yield. Multiple
linear regression models were fitted, to predict the pod yield based on the weather variables..