| dc.description.abstract | Seeds of spiderplant (Cleome gynandra L.) were sown in soil-filled 20-litre plastic
pots. The study was conducted to investigate the effect of salinity (NaCl) on the
growth, development and adaptation of C. gynandra. The experimental design was
based on randomized complete block design (RCBD) with replications. Two to four
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weeks after germination, the plants were subjected to five levels of salinity. Salinity
was applied by irrigating the pots daily with salt solutions of concentrations: 0 mol/kg
(control), 0.07 mol/kg, 0.13 mol/kg, 0.20mollkg and 0.26 mol/kg, which exerted
osmotic potentials of 0 MPa (control), -0.3MPa, -0.6MPa, -0.9MPa and -1.2MPa in
the rooting medium, respectively. Data on growth parameters was collected weekly,
including fresh and oven-dried weights of the whole plant as well as roots, shoots and
leaves; water content, chlorophyll content, leaf number, leaf weight ratio, root/shoot
ratio and days to 50% flowering.
Results showed that salinity significantly decreased the growth of the whole plant
as well as the growth of roots, shoots and leaves; and retarded flower emergence. The
Chlorophyll content was also reduced by salinity. Water content was initially reduced,
but recovered after some time, which was attributed to reduction oftranspiratory water
loss and osmotic adjustment. It also showed that spiderplant does possess a moderate
degree of salt resistance since plants were able to survive, grow and reproduce when
subjected to up to -0.9 MPa of salt stress in the soil. Factors contributing to this
resistance may include the species' capacity for osmotic adjustment and the presence
of a C4 photosynthetic (Hatch-Slack.) pathway. The age at which plants are exposed to
salinity may also be a factor in salt resistance.
The Spiderplant was concluded to possess a poor capacity both for regulating the
passive entry and translocation of salts, and also of compartmentalizing them, thus
allowing large amounts of salt to be absorbed and translocated to the shoots and
leaves, where they exerted such effects as retarding or inhibiting the processes of cell
division and expansion as well as decreasing photosynthesis and increasing respiration.
Observed root death was attributed to the deterioration of soil structure in the presence
of high concentrations of sodium ions. | en_US |
