MSc

Evaluation of differential effect of coloured shade nets on selected
ornamentals was undertaken in the Department of Pomology and Floriculture,
College of Horticulture, Vellanikkara. Six plant species viz., Nephrolepis exaltata,
Asparagus sp. (green leaf type); Spathiphyllum wallisii, Chrysothemis pulchella
(flowering type); Tradescantia spathacea „Sitara‟ and Cordyline terminalis
(coloured leaf type) were selected for the evaluation. The plants were grown
under shade nets of five different colours viz., red, yellow, green, blue and black.
Morphological data (both quantitative and qualitative), weather data including
temperature, relative humidity, light intensity and PAR (Photosynthetically Active
Radiation) were recorded for a period of one year from March 2015 to February
2016. The total chlorophyll and carotenoid contents were evaluated twice, at six
and twelve months after planting.
The plant growth in terms of height and spread was found to be greatly
influenced by red and black coloured nets as the plants under these two nets were
the tallest with more spread. Except for Cordyline terminalis, the growth of all
plants was the least when grown under blue coloured net. Height and spread of
Cordyline terminalis was the lowest under black colour net.
Leaf characteristics like area, length and breadth were the highest when
grown under black, followed by red coloured nets. The effect of yellow, green and
blue coloured nets was not significant. Red net only significantly increased the
number of leaves in all plants except Spathiphyllum wallisii, in which it was the
highest under blue colour net.
The internodal length was the longest in plants under red and shortest
under blue coloured nets except in Cordyline terminalis which recorded shortest
internodes under black net. Length and girth of petiole of all the plants were more
when grown under black net except that of Cordyline terminalis in which it was
the longest under red and blue nets.The floral characters of Chrysothemis pulchella were homogeneous under
nets of all colours while Spathiphyllum wallisii had bigger flowers with longer
stalks under black and red nets. The interval of flower production was the least in
red and maximum in plants under blue nets for both the plants.
Vase life was studied for those leaves that could be used as cut foliage. No
detectable difference in vase life of Asparagus sp. and Spathiphyllum wallisii
could be observed. But, leaves of Nephrolepis exaltata had maximum vase life
under black and red; medium under yellow and green and minimum under blue
nets. The vase life of Cordyline terminalis was minimum under blue net and
maximum under all the other net colours which were on par with each other.
A higher concentration of total chlorophyll as well as carotenoid were
found under black coloured net in all plants except in Spathiphyllum wallisii, in
which the maximum concentration was under blue net.
The maximum and minimum temperatures and relative humidity were
always higher inside the shade nets compared to the open condition. Both light
intensity and PAR were reduced inside the shade nets and the reduction was in the
ascending order of black, yellow, green, blue and red nets.
Overall growth of all the plants was higher under red and black nets, while
leaf characteristics were better under black net. Quality wise, the plants under
black net overshadowed those under red, yellow, green and blue coloured nets. It
was observed that all the plant parameters could not be improved by a single net
colour. This study will form a base for future works through which we can draw a
clear recommendation on the colour of shade net to be used for obtaining the
desired plant architecture which will enhance the commercial value of
ornamentals.