EFFECTS OF MOISTURE STRESS ON GERMINATION AND EARLY SEEDLING GROWTH OF THREE ACACIA SPECIES AND BALANITES AEGYPTIACA (L.) DEL.
EFFECTS OF MOISTURE STRESS ON GERMINATION AND EARLY SEEDLING GROWTH OF THREE ACACIA SPECIES AND BALANITES AEGYPTIACA (L.) DEL.
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Date
2007-11
Authors
GOTAN, YILLEK SIMON
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Abstract
Experiments were conducted in the laboratory and screen house to determine the effects
of moisture stress on germination and early seedlings growth of four savanna plants
species namely; Acacia albida, A. senegal, A.nilotica and Balanites aegyptiaca. Raising
seedlings for afforestation programmes in the savanna region of Nigeria has been a
problem because the seedlings used do not survive the long dry periods experienced
because they are exotic species. This research determines the effect of moisture stress on
the germination of three Acacia species and B. aegyptiaca and to evaluate some growth
parameters at the early seedlings stage exposed to four moisture stress levels. The
experimental protocol used a complete randomize design with three replications.
Laboratory experiment used ten seeds from each species and their dry weights determine,
placed in 9cm diameter Petri dishes lined with Whatman No.1 filter paper that had been
autoclave, kept near a beaker contain boiled water and covered by a bell jar for two
house. The differences between the dry seeds weight and imbibed weight after two hours
gave the imbibition rate. Seed coat diameter were measured with micro meter screw
guage. Radicle elongation of ten seeds from each species were measured for; 24, 48,72,
96, 120, 144 and 168 hours. The screen house experiment used 200cm3 plastic pots, four
plant species, four moisture levels and three replications. Two seeds per pots were sown,
the potted plants were arranged in four blocks of each containing 48 pots. Destructive
harvesting was carried out fortnightly eight times to determine seedlings growth
attributes. Acacia senegal had the highest imbibition rate, this indicates its thinnest seed
coat diameter provided faster movement of water into these seeds. Balanites. aegyptiaca
had the maximum radicle elongation after 144 hours; being the largest seeds were able to
absorbed more water that permitted longer radicle elongation. Seedlings growth attributes
varied significantly (P≤ 0.05) in response to the four moisture levels. Acacia albida
seedlings had the highest significant root length at the slight (M1) and moderate (M2)
moisture stress treatments. This indicated that the slight and the moderate moisture stress
treatment stimulated their roots length. Acacia senegal had the highest significant
(P≤0.05) shoot and root length increase at the severe moisture stress treatment (M3). This
suggest that exposure of these seedlings to severe moisture stress benefited the shoot and
root growth. Acacia nilotica had the highest shoot length, root length and shoot dry
weight at the control treatment M0. This probably indicates that these seedlings needed
more water during the early seedlings growth. Balanites aegyptiaca had the least growth
attributes at all the four moisture stress treatments, indicates that these seedlings grow
slowly at any moisture stress treatment in the early seedlings growth. The main
interaction (weeks after sowing X plant species, weeks after sowing X moisture levels,
plant species X moisture levels, weeks after sowing X plant species X moisture levels)
were all significant (P≤ 0.05) for the growth attributes studied. The correlation between
the growth parameters in each species was significant (P≤ 0. 05 and 0. 01) except in
shoot/root ratio that exhibited non significant association. These seedlings growth
attributes could be used for screening nursery stock for afforestation programmes in the
savanna region of Nigeria.
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR
THE AWARD OF THE DEGREE OF MASTER OF SCIENCE
BIOLOGY
DEPARTMENT OF BIOLOGICAL SCIENCES
FACULTY OF SCIENCES
AHMADU BELLO UNIVERSITY
ZARIA
NIGERIA
NOVEMBER, 2007
Keywords
EFFECTS,, MOISTURE,, STRESS,, GERMINATION,, SEEDLING,, GROWTH,, THREE,, ACACIA SPECIES,, BALANITES AEGYPTIACA (L.) DEL.