Nonstructural carbohydrate content in the stubble per unit area regulates grain yield of the second crop in rice ratooning

[摘要] Rice ( Oryza sativa L.) ratooning has attracted attention due to its higher yield potential. In the present study, a field experiment on rice ratooning using two rice genotypes, near isogenic line (NIL)- GN1A Takanari and Koshihikari, was conducted in 2019 and 2020 in southwestern Japan to obtain direct evidence for the role of stubble nonstructural carbohydrate (NSC) concentration and/or content per unit area on grain yield of the second crop and to determine the effectiveness of a gene producing more spikelets. NIL- GN1A Takanari is a near isogenic line carrying an allele of GN1A , which is a gene regulating the number of spikelets per unit area derived from an indica cultivar Takanari in the genetic background of a japonica cultivar Koshihikari, and it can produce more spikelets than Koshihikari. NIL- GN1A Takanari did not produce a higher grain yield of the first crop than Koshihikari in both years because NIL- GN1A Takanari had more spikelets m −2 but fewer filled spikelets and a lower grain weight. NIL- GN1A Takanari produced a lower grain yield of the second crop than Koshihikari because NIL- GN1A Takanari had fewer spikelets m −2 due to the fewer panicles. Also, NIL- GN1A Takanari had a lower NSC content than Koshihikari due to the lower leaf sheath plus stem weight in the stubble in 2019. Thus, the lower grain yield in the second crop of NIL- GN1A Takanari may result from the lower NSC content in the stubble. Additionally, the ability to produce more spikelets per unit area of NIL- GN1A Takanari was not demonstrated in ratoon crop under the condition of low NSC content in the stubble.

[学科分类] 农业科学（综合）