Abstract:
In the present study, the root vigor and kinetic ch
aracteristics of nitrogen absorption in
potato cultivars was investigated through sand cult
ivation and pot tests with nutrient
solution. Four cultivars of potatoes, namely, Feiwu
ruita, Yunshu301, Liangshu97, and
Chuanyu56 were grown in nutrient solution matrix cu
ltures. The result showed that: (1)
Nitrogen uptake rates differed significantly among
cultivars with different nitrogen
efficiencies; (2) cultivars with High nitrogen-util
ization-rate showed significantly higher
root vigor, the average root vigor values of cultiv
ars with the high nitrogen-utilization
were 115% at seeding stage, 53% at tuber-bulking st
age, and 18% at mature stage,
respectively, higher than those of cultivars with t
he low nitrogen-utilization; and (3) Root
vigor varied according to growth stage and nitrogen
supply i.e. cultivars with high
nitrogen-utilization-rate showed enhanced root vigo
r at the seedling stage under low-
nitrogen conditions, while cultivars with low nitro
gen-utilization rate showed reduced
root vigor at the tuber-bulking and mature stages u
nder high-nitrogen conditions. The
kinetic characteristics of nitrogen uptake differed
significantly among cultivars: (1) In
comparison with cultivars with the low, high nitrog
en-utilization showed lower
K
m
and
higher
V
max
values; (2) The
K
m
value for nitrate nitrogen uptake was higher than
that for
ammonium nitrogen uptake, especially in cultivars w
ith low nitrogen-utilization
，
，，
，
than
those of ammonium nitrogen; (3) In cultivars with l
ow nitrogen-utilization, the
V
max
value
for nitrate nitrogen was lower than that for ammoni
um nitrogen; and (4) In cultivars with
high nitrogen-utilization, the
V
max
value for nitrate nitrogen was the opposite. The s
tudy
provides a basis for breeding high nitrogen-utiliza
tion cultivars, thereby improving the
efficiency of nitrogen fertilization.
Keywords:
High nitrogen utilization, Kinetics of absorption,
Nitrogen form.
