Dry Matter Production and Distribution Characteristics of Perennial Rice Under Short-term Cycle Perennial Ratooning Cultivation

In order to explore the dry matter production and accumulation characteristics of perennial rice and one-year-old hybrid ratooning rice and their derived rice cropping patterns, and to deeply understand the physiological and ecological formation mechanism of perennial rice rhizome cultivation, thus providing a basis for promoting the sustainable perennial rice rhizome cultivation and achieving the high and stable yield, the ¹³C pulse labeling technology and crop physiological ecology methods were used to measure and analyze the yield variation differences of perennial rice in different rhizome cultivation seasons. The effects of of shortened growth periods and differences in dry matter production and distribution on the yield were also mainly studied. The results showed that compared with the first season rice of 151 days, the growth periods of the first ratoon rice (FRR) of 81 days, the second ratoon rice (SRR) of 126 days, and the third ratoon rice (TRR) of 80 days were shortened by 70, 25, and 71 days, respectively. The distribution pattern of dry matter in various organs of the plant was basically the same as that of the control group, i.e., the conventional hybrid ratoon rice (YY2640-FRR), specifically manifested as the increase in the allocation amount and allocation rate of dry matter and non-structural compounds to the above-ground grain sink with the advancement of grain filling, while the allocation amount and allocation rate to the organs such as stems, sheaths, and leaves decreased accordingly. Among them, the conversion and output rate of dry matter in stem and sheath significantly increased, and this phenomenon was more obvious in perennial rice. Based on the ¹³C isotope tracer technology, the research proved that compared with the main crop rice of perennial rice, the allocation amount and allocation rate of dry matter to the above-ground panicle organs in the later growth stage of perennial rice for ratoon rice were higher, but the allocation amount of ¹³C substances in other above-ground organs, especially stems, sheaths, and leaves, as well as in the underground soil, decreased season by season. In summary, it indicated that there was a significant synergistic and trade-off relationship between the yield of perennial rice and the dry matter production and resource allocation of its vegetative organs. It also reflected the important survival evolution strategy, which may be the key reason why the yield of perennial rice was difficult to maintain high and stable in the long-term ratooning cultivation.