Developing ratoon rice as forage in subtropical and temperate areas

Abstract

Developing ratoon rice as forage could increase forage yield without extra demand on the fields in subtropical and temperate rice planting areas. In this research, fourteen Indica rice varieties were first used in 2014 to select suitable ones as ratoon rice. The results indicated that the regeneration rate, regrowth tiller height, and the dry matter yield of Zhunliangyou 608 were significantly higher than other varieties (p < 0.05). In 2015 and 2018, Zhunliangyou 608 was set three cutting heights of first season (H15: 15 cm, H30:30 cm and H45: 45 cm), four gibberellic acid (GA) treatments with 60 g·hm−2 (GCK: spraying the same volume clean water to rice; G1, G6, G10: spraying GA on the 1st, 6th and 10th day after first harvest, respectively), and two harvest times for ratoon rice (T30 and T37 : the 30th and 37th day after first harvest, respectively), to investigate their effects on the yield and forage quality of ratoon rice. The results indicated that the T37H30G6 treatment was the best of all, for its ratoon rice feeding quality, in vitro dry matter digestibility (IVDMD) and nonstructural carbohydrates (NSC) content were higher than those of most other treatments in two years and its ratoon rice digestible dry matter yield (DDM) plus that of the first season rice straw was the highest of all. With the delay of ratoon rice harvest, the DDM, NSC and IVDMD increased, while the neutral detergent fiber (NDF) and acid detergent fiber (ADF) decreased. In conclusion, Zhunliangyou 608 could be used as ratoon rice in subtropical and temperate rice planting areas to produce good quality forage, with 30 cm stubble height for the first season, applying GA on the 6th day and cutting on the 37th day after first harvest with 5 cm cutting height.