Agriculture Reference
In-Depth Information
Table 6.2.( cont .)
Yield response to
narrower rows
Weed response
Weed- Weeds
Crop
to narrower rows a free
present Reference
Wheat
Shaktawat (1983)
V( )
0
Vander Vorst,Wicks & Burnside (1983)
Kukula (1986)
V(I)
0
Koscelny et al .(1990)
V( )
( ) ( ) Koscelny et al .(1991)
Solie et al .(1991)
e
Johri,Singh & Sharma (1992)
V(0)
0
0
Justice et al .(1993)
0
Teich et al .(1993)
V( )
V( ) 0
Justice et al .(1994)
Hashem,Radosevich & Roush (1998)
V
0
Blackshaw et al. (1999)
Notes:
a Symbols are as in Table 6.1.Studies were included only ifweed response to row spacing was
measured,or yield response to row spacing was measured with and without weeds.For studies
in which all treatment series included weed control measures,the row spacing series with the
least effective weed control was used for evaluation ofthe weed response and the yield response
in the presence ofweeds.
b Summarizes 27 experiments on barley,wheat,oat,and rye.
c Widest row spacing was ignored because it alone was cultivated.
d Crop leafarea index rather than yield.
e Nutrient uptake by the crop rather than yield.
because weeds between rows covered the crop earlier.Teasdale & Frank (1983)
had a related result in a field experiment with snap bean: the decrease in weed
fresh weight with narrower row spacing was larger and more consistent when
weed emergence was delayed for several weeks since this gave the crop a size
advantage in competition for light.Similarly,Harvey & McNevin (1990) found
that improvement of Panicum miliaceum control and sweet corn yield by
narrow rows was greater when the crop was planted in May rather than April,
possibly because of faster crop growth later in the season.These findings indi-
cate that crop arrangement should be considered in the context of integrated
weed management programs rather than as a stand-alone control tactic.
The relation between row spacing and weed management is considerably
more complex than an analysis of weed abundance and yield may indicate.
Prior to the widespread use of herbicides, row spacing in most row crops was
determined largely by the need to cultivate between the rows. The change
Search WWH ::




Custom Search