不同氮效率水稻生育后期氮素积累转运特征

ACCUMULATION AND TRANSLOCATION OF NITROGEN AT LATE-GROWTH STAGE IN RICES DIFFERENT IN CULTIVAR NITROGEN USE EFFICIENCY

以不同氮效率水稻基因型为供试材料,通过15N标记的氮肥盆栽试验精确定量不同氮效率的水稻齐穗后氮素积累和转运量。结果表明,无论在何种施氮水平下,氮高效水稻(南光和武运粳)的籽粒产量均显著高于氮低效水稻Elio;不同氮效率水稻在齐穗期和齐穗后15天时干物质积累量差异不显著,但在成熟期时氮高效水稻的干物质积累量显著高于氮低效水稻,增幅约为16·4%;与干物质积累相对应的是,不同氮效率水稻的氮素积累量在齐穗期和齐穗后15天也没有差异,但在成熟期时氮高效基因型水稻武运粳和南光的氮素积累量较氮低效基因型水稻Elio高约31%和21%,差异显著。15N标记试验结果可以看出,氮低效水稻Elio齐穗时吸收的一部分15N移出了植株体,其占15N转运量的11%。从齐穗至成熟,氮低效水稻Elio从茎叶转移出的15N量(2·75mg穴-1)远远低于氮高效水稻武运粳(3·54mg穴-1)和南光(3·22mg穴-1),差异显著。氮高效水稻武运粳和南光从茎叶转移出的15N量约占籽粒所需N量的91%和85%,而从土壤中吸收的15N量约占9%和15%。综上所述,氮高效、低效水稻氮素积累和转运特征的差异主要表现在齐穗期以后,氮高效水稻具有强的氮素吸收或者转运能力,以满足籽粒形成期植株对氮素的利用。

A pot experiment was conducted to study nitrogen accumulation and translocation quantitatively in rice plants different in cultivar and in nitrogen use efficiency （NUE） after full heading of the crop by applying 15Nfertilizer. Results show that Wuyunjing and Nanguang,two high NUE rice cultivars,were higher in grain yield than Elio,a low NUE rice cultivar,regardless of N application rates. No significant difference in dry matter accumulation and in N accumulation was observed between the rice cultivars of high NUE and of low NUE at the full heading stage and 15 days after full heading,but at the maturing stage Wuyunjing and Nanguang was 16.4% higher than Elio in dry matter accumulation,and 31% and 21% higher in N accumulation. The differences were significant. Results of the 15Nfetilizer experiment show that in Elio a portion of the 15N absorbed by the plant was translocated out of its stems and leaves,accounting for 11% of the total 15N translocated. During the growth period from full heading to maturity,the 15N translocated from the stems and leaves in Elio （2.75 mg hill-1） was much less than that in Wuyun （3.54 mg hill-1） and Nanguang （3.22 mg hill-1）. The differences were significant. The 15N translocated from the stems and leaves of Wuyunjing and Nanguang was equal to 91% and 85%,respectively,of the N in the grains,while the 15N the plants absorbed from the soil accounted for 9% and 15%,respectively of the total N absorbed. To sum up,the rice plants do not vary much in N accumulation and N translocation until the post-full-heading stage,and the high N absorption capacity and the strong N translocation ability of the rice cultivars high in NUE can satisfy the demand of the plants for N during their grain forming stage.