Meteorological Pre-warning Grade of High Temperature During Flowering Stage for Summer Maize in North China Plain

Abstract High temperatures during flowering stage affects the seed setting in maize and thereby result significant yield penalties recent changing climate era. Based on daily maximum temperature data of growing season from 1971 to 2019 at surface meteorological observatory Henan Province China observation agricultural observatory, an early warning grade high summer was constructed. The ≥ 32 °C as critical threshold disaster, 35 disaster. number days ( HD ) 10 were counted. sequence constructed its normal distribution characteristics verified. quartile value selected different grades, heat damage divided into three grades. index verification carried out by using kernel per ear station for maize. results showed that indexes corresponding with were: 3 ≤ < 5 (Grade I), 7 II), III) 2 III). verified follows, about 90% stations significantly negatively correlated grains ear, 74% which ear. Applying this evaluate risk period, we can indicate had trend increasing gradually north south. In conclusion, could accurately reflect stage.