Liquid Culture Systems for in vitro Plant Propagation

306 Christopher Hunter & Lionel Levy
A digital camera and Clickometer TM software were used to record,
weekly, SE numbers and development in each replicate culture. At each
observation, each SE was ascribed to a ‘development stage’ (Hakman and
von Arnold, 1988) ranging from Stage I and II (immature, < 2 mm long), to
III (intermediate, length > 2mm), to IV in which cotyledons were well
developed and c. 3mm long. Stages are referred to as S1, SII, SIII and SIV.
3. Results
FW:DW ratio (n=20) for SA was 4.93% and 4.95% for AA. As these
means were not statistically different, results of SE development in this
paper are able to be expressed, with some confidence, on the basis of FW (g)
of inoculum.
At the time of inoculation only proembryos and slightly later stage SEs
were visible microscopically in both SA and AA cultures. Following
transfer to maturation medium, SI and SII SEs differentiated: by week 6, SA
cultures (Figure 1a) had 75 SEs g -1 (T0) to 172 SEs g -1 (T10) which
decreased to 14 SEs g -1 (T0) to 53 SEs g -1 (T10) by week 10. SI and SII AA
cultures (Figure 1b) were maximal at week 7 (between 161 and 174 SEs g -1 ),
decreasing to between 71 and 104 SEs g -1 at week 10: throughout the period
there was no substantial treatment difference. Plates 1 and 2 show the effect
of the culture response to the presence of silver nitrate at week 10.
In SA cultures, numbers of SIII SEs (Figure 2a) increased from 6 to 14
(T0), 5 to 20 (T100), 25 to 45 (T1 and T10). In AA cultures (Figure 2b)
there was little change overall in yield during the 5-week period (23
increasing to 26 SEs g -1 for T0, 41 increasing to 47 for T1, 52 decreasing to
50 for T10 and 62 decreasing to 41 for T100): the yield for T0 was
significantly less than the other concentrations.
SIV SE numbers for SA cultures (Figure 3a) were zero at week 6, but
thereafter increased linearly to week 10. SIV SE numbers for AA cultures
(Figure 3b) ranged from 7 to 23 at week 6, to between 18 and 59 at week 10.
The yields of T0 were always significantly lower that the other three silver
nitrate treatments.