| The SPAD value, photosynthetic characteristics, and chlorophyll fluorescence par
ameters of wheat flag leaf after flowering stage were studied in a 2 year locat
ed experiment in semi arid areas of southern Ningxia Autonomous Region using fi
ve tillage practices of successive no tillage (NT), successive subsoiling (ST),
subsoiling/no tillage(ST/NT), no tillage/subsoiling (NT/ST), and conventional
tillage (CT). The results showed that the chlorophyll relative content under ST
, NT/ST, ST/NT and NT were 32.2%, 27.4%, 13.5%, and 11% higher than CT, respecti
vely, from flowering to filling stage. Compared with CT, the flag leaf daily ave
rage photosynthesis rate (Pn) of different tillage treatments increased by 1
.6, 1.2, 0.9, and 0.6 μmol·m-2·s-1(P＜0.05), and the transpir
ation rate (
Tr) increased by 1.2, 0.9, 0.7, and 0.3 mmol·m-2·s-1(P＜0.
05). The wa
ter use efficiency of flag leaf uder ST and NT/ST was significantly higher than
that of CT. In the flowering and filling stages, compared with CT, the values of
Fv/Fm, Fv/Fo, φPSⅡ, qP
and qN increased and the photoinhibition degre
e decreased for the ST, NT/ST, ST/NT and NT treatments. Grain yields increased b
y 42.1%, 35.3%, 30.3% and 23.5% under the NT/ST, ST, ST/NT, and NT treatments. T
he WUE based on crop yield increased by 51.3%, 37.8%, 19.9% and 14.6% respec
tively, compared with the CT. The continuous no-tillage, subsoiling, and two ro
tation tillage practices could improve the crop transpiration efficiency with li
mited rainfall in dryland, and reduce invalid evaporation of soil moisture. Even
tually, the grain yield and WUE of the ST and NT/ST treatments were significantly improved. |