New Zealand Journal of Agricultural Research abstracts
Selection in Setaria sphacelata for winter survival
L. Jank
Embrapa Beef Cattle
CxP. 154
CEP 79002-970 Campo Grande
MS, Brazil
K. H. Quesenberry*
Agronomy Department
University of Florida
Gainesville
Florida, USA
A. R. S. Blount
North Florida Research and Education Center
University of Florida
Quincy
Florida, USA
P. Mislevy
Range Cattle Research and Education Center
University of Florida
Ona
Florida, USA
Abstract Choice of warm-season grasses for use in North
Florida, United States, is limited because of the cold winters, which are
characterised by both radiation frosts and freezes. With the objectives of
increasing the adaptation of the forage Setaria sphacelata to these
conditions, a breeding programme was undertaken at the University of Florida
from 1997 to 2000. A recurrent selection procedure was used for three cycles
to select for winter survival and early spring growth after frost and freezes
in Gainesville (29.6°N latitude) and for one cycle in Quincy (31°N
latitude). Heritability estimates for the first two cycles in Gainesville
and the cycle in Quincy ranged from 0.35 to 0.50 on a family basis. Predicted
gains ranged from 10.4 to 17.4% in winter survival over the preceding cycle.
These populations were compared in Gainesville to the original population
and to cultivars ‘Solander’ and ‘Splenda’ in two experiments, one wide- and
one close-spacing. Results showed that selection for winter survival in Gainesville
reduced canopy height in the second and third cycles and the reproductive
height in the third cycle. Leaf dry matter yield was decreased in the first
and second cycles and leaf percentage in the first cycle. These effects were
reversed in the remaining cycles. Selection did not have a consistent effect
on the width of leaves, length or number of inflorescences, or on total and
stem dry matter yields. However, selection for winter survival in Quincy increased
canopy height and the number of inflorescences. Selection for winter survival
after frosts and freezes in Gainesville was successful because all cycles
of selection had a higher survival rate after the winter of 1999-2000 than
the original population. This winter, which killed many of the Setaria
plants, was effective in providing additional screening for winter survival
after frosts and freezes. Further research with this species for Florida conditions
appears warranted.
Keywords frost tolerance; breeding; Setaria sphacelata;
Florida; freezes; winter killing; subtropical grasses; survival; ‘Solander’;
‘Splenda’.
A02003 Received 28 January 2002; accepted 15 July 2002; published 9 December
2002
New Zealand Journal of Agricultural Research, 2002, Vol. 45: 273-281
0028-8233/02/4504-0273 $7.00/0 © The Royal Society of New Zealand
2002
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