Proceedings of the XLVII Italian
Society of Agricultural Genetics - SIGA Annual Congress
Verona,
Italy - 24/27 September, 2003
ISBN 88-900622-4-X
Poster
Abstract - 2.10
FOUR AND EIGHT-CONSTITUENTS
FREE-HYBRIDS IN ALFALFA. DRY MATTER YIELD FROM DIALLEL CROSSES: SOWING YEAR
RESULTS
P. ROTILI*, C. SCOTTI*, S. GNOCCHI*, D. KERTIKOVA**,
G. GNOCCHI*
*) Istituto Sperimentale Colture Foraggere, Lodi,
Italy
**) Institute of Forage Crops, Pleven, Bulgaria
alfalfa, diallel cross, free-hybrid, pod fertility
General
objectives: a) Construction of free-hybrids in alfalfa (Medicago sativa
L.),using partially inbred (S2) parental plants (Rotili et al.,
1999). b) Experimental evaluation of free-hybrids and synthetics derived from
the same parental plants (Table 1).
Table 1. Free-hybrid program
|
4 -
constituents |
8 -
constituents |
||
|
A B C D
|
E F G H I L M N
|
||
1997 |
Diallel cross
|
Diallel cross
|
||
1998 |
6 2S2Syn1
(SH) |
4S2Syn1
|
16 2S2Syn1 (SH) |
8S2Syn1 |
1999 |
6 2S2Syn2
|
4S2Syn2 |
8 S2DHF1 |
8S2Syn2 |
2000 |
6 2S2Syn3
|
4S2Syn3 |
8 S2DHF2 |
8S2Syn3 |
2001 |
Diallel
cross
|
|
Diallel
cross
|
|
|
15 S2DH |
4S2Syn4 |
28 S2OH |
8S2Syn4 |
2002-03 |
Agronomic Test
|
SH: Simple Hybrid; DH: Double Hybrid; OH:
Octuple Hybrid
4-constituents program: partly inbred (S2)
constituents originating each from different sources (groups A and B). Diallel
crossing among 6S2Syn3 parents to obtain Double Hybrids (DH).
8-constituents program: partly inbred (S2)
constituents originating each from different sources (group C), each from two
different sources (group E) and each from a single cultivar (group D). Diallel
crossing among 8 S2DHF2 to obtain Octuple Hybrids (OH).
The trial was
planted in a cold greenhouse, in concrete boxes 25x80x65 cm containing two rows
of plants (final density of 250 plants/m2), in a randomized block
design with 5 blocks. Data were collected on the 15 central plants of each row,
each population being then represented by
150 plants; irrigation was not limiting. Five cuttings were made during
the sowing year; dry matter yield, earliness and mortality were recorded at
plot basis.
At the
4-constituents level, only one hybrid significantly outyielded for the total
year production the corresponding synthetic 4S2Syn4 (+ 29%),
although 8 and 2 hybrids respectively in the two diallelic groups showed dry
matter production 10-23% higher than the corresponding synthetic. At the
8-constituents level, the hybrids were not different or significantly less
yielding than the corresponding 8S2Syn4.
As for the
free-hybrids, 4-constituents model resulted significantly more performing than 8-constituents
one; the synthetics at 4 and 8 constituents did not differ significantly in
Syn4 generation while in Syn3 the 4-constituents model showed higher DMY than 8-constituents
one.
Both G.C.A. and S.C.A. variances were highly significant in
all the diallelic groups. However, S.C.A. resulted more important than G.C.A.
in the 4-constituents crosses while the opposite was true for the
8-constituents crossings.