Abstract:
An experiment was conducted at the Eastern University, in Batticaloa district of Sri
Lanka during the ‘Yala' 2007, to determine the influence of moisture stress on certain
agronomic parameters of tomato (Lycopersicon esculentum Mill.) at different growth
stages. The experiment was arranged in the Randomized Complete Block Design
(RCBD) with five treatments and four replications. The parameters measured were Leaf
Area Index (LAI), Root Length Density (RLD) and Specific Leaf Area (SLA).The yield
was also determined. The total fresh weight of harvested fruits of each plot was
obtained separately for yield determination. Moisture stress was imposed during the
vegetative, flowering, early fruiting and fruit ripening stages. A period of four days
stress was given during the above growth stages and the experiment was managed in
accordance with the recommended cultural practices. Rain shelters were constructed to
prevent the entry of rain water into the excremental plots during rainy days. The data
were statistically analyzed using the Analysis of Variance (ANOVA) to detect the
significance between treatments. The differences between the treatments were
compared by Duncan’s Multiple Range Test (DMRT).
Moisture stress reduced the LAI, RLD and SLA of tomato irrespective of the stages of
growth. The highest reduction in LAI was observed during the vegetative stage. It was
46.42% compared to control. The reduction of RLD may be due to the inhibition of root
growth by reduced cell expansion. The flowering stage showed the highest reduction in
the RLD. It was 14.04 % compared to control. The highest reduction in SLA was
observed when the stress was imposed during the vegetative stage. Moisture stress
reduced the yield of tomato and the reduction was highest when the stress was imposed
during the flowering stage. It was 58.82% compared to control. This reduction was
mainly attributed to reduced number of flowers, reduction in the size of newly formed
flowers and the abscission of flowers and flower buds during the flowering stage.
Hence, the flowering stage was identified as the most critical stage of growth sensitive
to moisture stress in tomato.
