Studies of vegetative propagation of the lychee (Litchi chinensis ...

2000, 5000 and 10 000 ppm each of NAA-Na
and IBA separately and 2000, 5000 and 10000
ppm mixture of equal parts ofNAA-Na and IBA.
Treatments were prepared as powder to which
10% Dithane M-45 fungicide was added. Both
vermiculite and air temperatures were recorded at
9 am, 12 noon and 3 pm (local time) at 2-day
intervals for 8 weeks and thereafter at 1O-day
intervals. Relative humidity within the polyethylene
enclosure was recorded by a hygrothermograph.
At termination of the experiments on 9 & 17
November for the Kona and Poamoho subjects
respectively, the cuttings were dug up, and the
number rooted, the number of roots per cutting,
the average length of roots, the number callused
and the number dead were recorded.
Grafting experiments
Rootstocks for these experiments were obtained
from the Poamoho Experimental Station. Four
hundred and thirty suitable branches were selected
on each of the three cultivars and air-layered.
When enough roots developed, the air-layers were
harvested and potted in 3-gallon cans and set in
shade until a new flush of growth appeared, after
which they were acclimatized. In September 1965,
70 air-layers each of Kwai Mi, Hak Ip and
Brewster were transferred into nursery rows on
the Manoa Campus Experimental Farm. The
remaining air-layers were left in the cans for the
photoperiod experiments.
Scionwood for the grafting experiments also was
obtained from the three cultivars at Poamoho. For
scionwood, branches 0·6-1·0 em in diameter were
selected from mother trees and girdled on 9 Oct 65.
Girdled and non-girdled scionwood were harvested
on 9 December, and 8-10-em scions were sidegrafted
to 60 each of the three stock cultivars under
normal daylength. For the 8- and the 16-hour day
photoperiods only Hak Ip rootstock was used with
girdled scions from the three cultivars.
All rootstocks were side-grafted on 10 December
and then transferred to their respective photoperiod
regimes. The 16-hour day plants received
9·5 h sunlight daily and 6·5 h supplementary light
from two 100-watt incandescent bulbs suspended
0·9 m above the tops of the plants.
The experiments were terminated on 10 Mar 66
and percentage takes were recorded for each treatment.
Successful grafts were then harvested, fixed
in Craf III solution for 5 days and then transferred
to 70 % ethyl alcohol until sectioned. Sections were
cut on the sliding microtome at 25fL without
embedding, stained in Safranin and Fast Green
and mounted in Canada Balsam.
Histological studies
For histological studies inarching technique was
employed. However, a few Kwai Mi and Brewster
side-wedge grafts were also made. One hundred
and forty air-layers of the three cultivars in cans
were inarached in different combinations on
5 Nov 65. The first grafts were harvested 2 weeks
later and then at 10-day intervals thereafter until
January 1966. The last harvest was taken on
10 March, 115 days after inarching. All grafts
were fixed, sectioned, stained and mounted as
previously described.
Sample preparation and carbohydrate determination
Girdled and non-girdled sample twigs from
Kona and Poamoho were harvested at the same
time of taking cuttings for rooting. Twigs were
chopped up, oven-dried at 60°C for 12 h and
ground in a Wiley Mill with a 4-mm mesh.
Similar twigs used as scionwood in the grafting
experiments were also taken for analysis. For these
latter determinations, girdled twigs were sampled
at 3-week intervals until scions were taken for
grafting at 9 weeks. Samples taken from nongirdled
twigs on each date served as controls. The
samples were prepared as already described. Two
determinations were made for each sample and the
mean recorded.
Sugar was extracted from 2 g samples with 90
em 3 of 80 % ethyl alcohol. Total sugar was then
estimated in 5 em 3 aliquots according to the
Shaffer-Somogyi Micro Method (Horwitz, 1960).
For starch determination, the residue from each 2 g
sample after sugar extraction was digested with
diastase solution for 30 min at 38°C, then refluxed
with concentrated hydrochloric acid for 2 h.
The resultant solution was filtered and 2 cm 3
aliquots used in the determination of the reducing
power of sugar (Horwitz, 1960). The Shaffer-
Somogyi Dextrose- Thiosulphate Equivalent Table
(Horwitz, 1960) was used for the estimation of
total sugar. A factor of 0·90 (glucose to starch) was
used to convert percentage sugar to starch.