New Zealand Journal of Crop and Horticultural Science abstracts
H99043Received 1 November 1999; accepted 18 August 2000
Effect of shade on growth and photosynthesis of Panax ginseng
GRAEME PARMENTER
New Zealand Institute for Crop & Food
Research Ltd
Private Bag 5004
Mosgiel, New Zealand
ROGER LITTLEJOHN
New Zealand Institute for Agricultural
Research Ltd
Private Bag 5004
Mosgiel, New Zealand
Abstract Panax ginseng C.A. Meyer was grown in raised
beds at Mosgiel, New Zealand (Lat. 45deg. 51[[minute]]S Long. 170deg.
22[[minute]]E) at 2, 8, 20, and 36% of ambient irradiance. Mean root weight at
planting was 2.0 g. Plants began to emerge on 29 September 1994 with a
median emergence date of 15 October 1994. Seventy-seven percent of plants
emerged; emergence probability was strongly associated with bud size. Half of
the roots that failed to emerge survived until autumn and doubled their bud
size during summer. Root death was associated with low root weight. Leaflet
area was well predicted by leaf length or width. On leaves bearing five
leaflets, relative areas of the three leaflet size classes were 1:4:5 allowing
whole plant leaf area to be predicted accurately from the central leaflet area,
even when some leaflets were missing. At plant harvest in April, mean final
root weight was 5.5 g. Final root weight was strongly associated with
initial root weight, but for any given initial root weight, final root weight
was lower and increased less as initial root weight increased in the low light
treatment (2%) than in other treatments. Leaf area was also strongly associated
with initial root weight, and for any given initial root weight, leaf area was
lower and increased less as initial root weight increased in the high light
treatment (36%) than in other treatments. Leaf area per plant was
61 cm
2 in the high light treatment (36%) compared with an
average of 116 cm
2 in the other treatments. Even after
accounting for the association of initial and final root weight, there was a
positive effect of leaf area on final root weight. Final bud length was
positively associated with final root weight, but for any given final root
weight final bud length was greater in the low light treatment (2%) than in
other treatments. Leaf senescence occurred earlier the higher the irradiance.
Chlorophyll fluorescence Fv/Fm ratios, measured in January, were 0.763 at 2%
irradiance, significantly (
P < 0.05) greater than values for plants
at 8 and 20%, which were not significantly different. Fv/Fm at 36% irradiance
was 0.646, significantly (
P < 0.01) lower than in the other
treatments but indicative of only mild photoinhibition. Low leaf area, mild
photo-inhibition, and shorter leaf duration at the highest irradiance (36%),
appear to have been balanced by higher rates of photosynthesis, resulting in
similar root growth in 8-36% of ambient irradiance.
Keywords ginseng; Panax ginseng; bud length; plant
emergence; root weight; root growth; leaf area; fluorescence; photosynthesis
New Zealand Journal of Crop and Horticultural Science, 2000, Vol. 28:
271-275
0014-0671/00/2804-0271 $7.00 (c) The Royal Society of New Zealand 2000
PDF file of entire paper: medium quality (597K); (scanned from paper original: notes about this process)
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