الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 102 |  |  |
| | | from | 102 | | |
Abstract
This study was suggested as an attempt to investigate the general effects of planting date and spacing as well as their interaction on yield and quality of seed production of onion (cv.
Giza 20) from sets compared with mother bulbs. Two field experiments were carried out during the two successive winter seasons ’of 1992-1993 and 1993-1994 at the Nubaria Agric. Res.
Stat, North of Tahrir region.
A split-plot system in a randomized complete blocks design
with sixteen combinations~ replicated four times, was used in both
experiments. Treatments of each experiment consisted of all
possible combinations of four planting dates (Nov. 15th. Dec. 15th.
Jan. 15th. and Feb. 15th) as main plots within four plant spacings
(sets at 10~r-5.and20 em and mother bulbs at 20 em) as sub-plots.
Data were recorded for the characters of some growth
parameters, flowering behaviour of main scape, main umbel, seed
yield and seed quality as well as the correlation between four of the
important characters. The obtained results are summarized as - .
follows:
·67
1. Some plant growth parameters:
a) The percentage of emergence.
Such character was not clearly affected by either planting date, the spacing or the interaction between these two factors at both seasons of this trial.
b) Number of sprouts per plant:
Earlier plantings (Nov. or Dec. 15th) significantly increased
the number of sprouts per plant at both seasons in comparison with
the other planting dates. Moreover, planting the mother bulbs at 20
em apart significantly increased number of sprouts per plant than
planting sets at anyone of the used spacings. Regarding the effect
of interaction, the number of sprouts was significantly increased
when mother bulbs were grown at 20 em apart on Nov. or Dec.
15th.. such treatment resulted in the highest values in this regard.
2. FloweriDg bell.viour:
a) Main scape parameters:
The number of days from planting date to the emergence of
the first main scape, the period needed for main scape performance
and the period of complete appearance of main scape in both
seasons of this trial were significantly decreased with successive
dates of planting (from Nov. 15th up to Feb. 15th). Mother bulbs
grown at 20 em significantly 4ecreased the number of days of each
of such studied flowering ctwaeters· The combined effect of
planting date and spacing was the same of the single effect of each
one of them where growing mother bulbs at 20 cm on Feb. 15th.
resulted in the lowest values in this respect compared with any
other treatment.
b) First flower measurements:
The number of days to anthesis of the first flower on the main
umbel, .period required for the first flower appearance and number
of days to complete apearance of the first flower were significantly
decreased with delaying planting date from Nov. 15th up to Feb.
15th.. Moreover, planting sets at any used spacing (10, 15 and 20
em) did not show clear variations in this respect, while planting
mother bulbs at 20 em apart significantly decreased the number of
days needed for it. Generally, planting the mother bulbs at 20 em.
apart on Feb. 15th.showed the shortest period in this respect.
c) Characters of main umbel:
.. Total number of main scape, height and diameter of the main
umbel ~ well as the fresh and air-dried weights of umbels per plant
were gradually and significantly decreased with delaying date of
planting from Nov. 15th. up to Feb. 15th.The highest values were
found with the earliest planting date (Nov. 15th.) where the lowest
ones were related to the last planting date (Feb. 15th). The
variations between different tested spacings of sets (10, 15 and 20
em) were not significant as wide as between sets and mother bulb
at 20 cm apart, which planting resulted in the highest values except
in the case of umbel diameter which was of lower values with
69
mother bulb. However, planting sets at wider spacings (15 and 20
em) resulted in significantly bigger diameter of main umbel than
that of sets planted at 10 cm apart. Planting mother bulbs at 20 em
apart on Nov. 15th. resulted in the highest values of studied main
umbel parameters.
3. Seed yield:
Earlier planting i.e., Nov. 15th. resulted in the highest values
of all studied seed yield measurements (glumbel, glplant or
l”21faddan) at both seasons. Delaying planting date from Nov. ·15th.
wp to Feb. 15m. gradually and significantly decreased such values.
The seed yield per umbel or ·plantwas significantly and gradually
increased with increasing the spacing of planting sets from 10, 15
up to 20 em. However, seed yield per faddan was significantly
increased with decreasing plant spacing of sets from 20, 15 up to
10 em. Moreover, growing sets at 10 em apart on both sides of
ridges or mother bulbs at 20 em apart produced nearly the same
higheSt seed yield pef faddan.
The highest seed yield per umbel was obtained with sets
grown on Nov. 1511lat 20 em apart. However, the highest seed
yield per plant was produced from planting mother bulb at 20 em
apart on the same Pate. Meanwhile, the highest seed yield per
tiddan was JlIOduc1d iIlIII pIaIUing seIS at 10 em apart or mother
bulb at 20 em apart to Nov. 1Sm. ~.
”
r ..••.’ .
70
4. Seed quality:
Weight of lOOO-seeds (g) and gennination (%) were
significantly and successively decreased with delaying the date of
planting- from Nov. 15th. up to Feb. 15th. However, the rate of seed
germination was not significantly affected in this respect.
The weight of IOOO-seeds (seed index) and (%) of
germination were significantly increased with increasing the plant
spacing, while the rate of seed germination was not significantly
affected in this respect. The combined effect of planting date and
spacing did not show significant variations regarding seed quality.
s. correlatioD studies:
ResultS of·correlation between characters may be summarized
as follows:
1- High and positive correlation between number of sprouts and
number of scapes, number of sprouts and seed yield/plant as
well as number of scapes and seed yield/plant was found.
. ,,
2- Studying number of sprouts, number of scapes or seed
yield/plant and their relationship with diameter of main umbel,
showed negative correlations in all treatments of this study.
Onion breeders may take benefits from these correlation studies
- in their breeding and selection programs.
----
71
Finally, it may be concluded that planting mother bulbs of
onion on one side of ridge at 20 em apart or growing the sets at 10
em apart on both sides of ridges on Nov. 15th. may be
recommonded for getting high seed yield with best quality.
However, from the economical point of view, taking in
concederation the high costs of using mother bulbs of good quality
costs too much money which leads to the final conclusion that
using small sets instead of the traditional method of using mother
bulbs is preferable.