Effects of different sowing dates on yieid and protein content of spring wheat Responses of Endogenous Hormone Contents in Leaves of Main Stem in Different Developmental Stages of Winter Wheat Varieties Sowed in Spring Impact of different sowing dates on green water footprint of maize in western Jilin Province Effects of sowing date on 2-acetyl-1-pyrroline content and yield of late season aromatic rice Spectral Monitoring of Winter Wheat Above-ground Dry Biomass in Various Sowing Dates