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Results and
discussion
1. Spraying time identification: In 1988, 7,000 ppm for EK or
6,000 ppm for ES were sprayed on Jinfeng 1 at the shealth length of
flag-leaf of 0, 2, 3, and 4 cm. Light microscope examination for
young spike differentiation was made at same time. The effective
spraying time for the two CHAs were from sporogenous to meiotic
stage, it was flagging time in field. The average shealth length of
flag-leaf was -2 to 2 cm. Monokaryon stage seems to be critical time
for spraying and after that the MS decreased to 79% for both
chemicals. The result is shown in Table1.
Generally speaking, this stage will be last 4 to 5 days for a
cultivar in field. The date of spraying could be selected according
to the weather.
2. Identification of spraying concentration: in 1989, Jinfeng 1 used
as female, Jimai 21, male, respectively. Concentration experiment was
made on flagging time with the dosage of 1,350 kg/ha. The best MS and
the best SS has got under the concentration of 7,000 ppm for EK and
6,000 ppm for ES, respectively. Results are show in Table
2.
3. Comprehensive assessment to the two CHAs.
(1) The interaction between CHAs and cultivars: In 1990, the
experiment about same CHA to different cultivars and about same
cultivar to different CHAs were carried out. Results are shown
in Tables 3
to 5.
In 1990, 70 cultivars which flagging time are relatively similar to
each other was sprayed with EK and ES at flagging time. The
characteristics analyzed are shown in Table
6.
The average MS of 70 genotypes treated with them was over 95%, in
which only several cultivars shown different suggest that different
genotype maybe have a different response. The pretesting should be
made in order to get satisfied hybrid. The two CHAs have a side
effect on plant height as well as on the length of last internode,
that is, shortening of them after spraying. Generally speaking, the
higher the plant is, the shorter it becomes by spraying. The
decreasing extent was from 8.4 to 32.4 cm and from 7.1 to 32.1 cm for
plant height and the length of last internode, respectively. The
ratio of the latter to the formers was 1: 2.8 before spraying, where
it become 1: 3.8 to 1:3.9 after spraying.
(2) Hybrid seed production. In 1992, EK was used to produce hybrid
Huayou 9, 74197/888-1, in 0.53 ha in Louzi village. The females yield
was 4,223 kg/ha. The male yield was 4,695 kg/ha, indicating only
472.5 kg/ha yield decreasing or 90% more male's yield.
(3) The main composition of the two CHAs was Ethrel, which is widely
used both in crops and fruit production. Except the plant height
decreasing after spraying, there were no another side effect like
heading difficulty, spikelet aborting and green spike increasing
caused by Ethrel mono-spraying. These CHAs have no air pollution, no
remnant and their costs are low. The outcrossing rate varied from
71.33-86.49% for the female whose MS were over 95%, maybe the
variation was caused by different flowing time of both male and
female, the practical cross ability was satisfied had shown their
utilizing potential.
(4) The length of last internode of plant is a heritable character.
Differences have been observed among 70 cultivars. The proportion
varies from 1: 2.04 to 1: 3.94. Genotypes being longer length of last
internode is more suitable for female because it becomes shorter
after spraying. On the other hand the outcrossing rate would be
improved by selecting the synchronizing flowering parents
and breeding
good flowering habit parents.
References
Johnston RA (1985) Hybrid wheat economics looking, better all the
time. Crop and Soil Magazine. August-September: 15-18.
Li ZQ (1989) Preliminary report on male killing with ES and applied
technique of strong superity combinations gained in wheat. In
Chinese. J. Hebei Normal University. 3: 128-131.
Liu LX (1990) Practice and outlook of crop breeding with chemical
hybridizing agents. in Chinese. Scientia Agriculture Sinica. 23 (2):
1-9.
Rowell PL (197 1) Induction of male sterility in wheat with
2-chloroethphonic acid. Crop Sci. 11: 629-631.
Tschabold EE (1988) LY 195259, New chemical hybridizing for wheat.
Crop Sci. 20: 583-588.
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