Studies on the Difference of Flowering and Fruity Period Between C3 and C4Herbaceous Plants of Poaceae in South Subtropical and North Temperate Climatic Zones of China

Abstract:

Reproductive phenology is a key indicator of plant individual reproduction and population succession. to reveal the influence of climate factors on the flowering and fruity period of C₃ and C₄ plants of Poaceae in different regions, Guangdong Province and Inner Mongolia Autonomous Region represent the south subtropical and north temperate climatic zones of China, and three reproductive phenological traits of 395 and 265 herbaceous species of Poaceae were obtained based on floras, respectively. The differences in initial flowering time, final flowering time and flowering duration between the two regions were compared, and the correlations between phenological traits and climatic variables (mean annual temperature and mean annual precipitation) were studied. The results showed that the start flowering stage of C₃ grasses in two regions was earlier than that of C₄ grasses. The C₄ common species of two zones had earlier initial flowering time, later final flowering time and longer reproductive period in south subtropical zone, while there was no significant difference in final flowering of C₃ common species, but the initial flowering stage was earlier and the reproductive period was longer in the south subtropical region. With the increase of annual temperature, the initial flowering time in north temperate region was advanced, but it was delayed in south subtropical region. With the increase of annual precipitation, the initial flowering time and final flowering time were delayed, and the reproductive period had no relation with neither mean annual temperature nor mean annual precipitation. The cross-regional analysis showed that the final flowering time and reproductive period were positively correlated with the mean annual temperature and annual precipitation, but did not the initial flower time. The significant difference in initial flowering time of common species was caused by higher sensitivity of C₃ grasses to climatic difference between two zones than C₄ grasses. The significant difference in reproductive period of common species was driven by the late end of final flowering time of C₄ grasses, which was more sensitive to regional climate differences. Therefore, it was clarified patterns and reasons of different reproductive phenology of Poaceae herbaceous species, and their adaptation strategies to temperature and precipitation across climatic zones.