Abstract:
Moisture deficit is often the major factor inhibiting crop yields in semi–arid
and arid regions. An induction of moisture stress in plants is known to
trigger several biochemical changes. Free proline accumulation and changes
in the chlorophyll content of leaves are some of the important biochemical
responses to moisture stress. A study was conducted to investigate the effect
of moisture stress on “free proline” and “chlorophyll a” contents of selected
tomato cultivars. Tomato cultivars ‘KC 1’, ‘Roma’ and ‘Thilina’ were used
for this study. The experiment was arranged in a 3 × 2 factor factorial
Randomized Complete Block Design with six treatments, which replicated
four times. Moisture stress was imposed for the ‘KC 1’, ‘Roma’ and
‘Thilina’ cultivars of tomato for a period of six days in treatments one, three
and five. Regular watering was practiced for treatments two, four and six of
the above cultivars at two days interval to Field Capacity. The “free
proline” and “chlorophyll a” contents were determined for the stressed
plants on the 6th day from the commencement of the stress. Moisture stress
significantly increased the “free proline” content but reduced the
“chlorophyll a” content of leaves of all the tomato cultivars. The highest
amount of free proline content (6.2 mgcm power -2) was obtained in the ‘KC 1’
tomato cultivar followed by ‘Roma’ (4.3 mgcm power -2) and ‘Thilina’ (3.1 mgcm power -2).
Similarly, the highest amount of “chlorophyll a” content (11.7 mgg power -1
fresh weight) was observed in the ‘KC 1’ tomato cultivar followed by ‘Roma’
(7.3 mgg power -1 fresh weight) and ‘Thilina’ (4.6 mgg power -1fresh weight). Based on
the “free proline” and “chlorophyll a” contents, it could be concluded that
‘KC 1’ tomato cultivar was able to resist drought comparatively better than
‘Roma’ and ‘Thilina’.
