2005 Volume 74 Issue 3 Pages 350-356
A newly released supernodulating soybean cultivar Sakukei 4 was previously characterized as having a superior capability of nitrogen fixation and photosynthesis, and therefore to be potentially high-yielding. To examine the yield performance of this cultivar in Miyagi, we conducted three experiments (Exp. 1 - 3) at two locations (Sendai and Naruko) for two years (2001 and 2002) placing emphasis on the effects of nitrogen supply. Sakukei 4 was grown by applying controlled nitrogen release fertilizers (LP-70 or LP-100) or urea, and the growth and yield were compared with its parental normally-nodulating cultivar Enrei and non-nodulating genotype En1282. In Exp. 1 (2001, Sendai), the yield of Sakukei 4 and Enrei was the highest in LP-100 plot followed by LP-70 plot and the lowest in the urea plot. In Exp. 2 (2002, Sendai) and Exp. 3 (2002, Naruko), the top dry weight in the LP-100 plot at flowering and seed filling stages exceeded that of the urea plot, and this was more pronounced in Sakukei 4 than in the other genotypes. The increased dry weight of Sakukei 4 by the application of LP-100 depended on an increase of leaf area. In Exp. 2 and 3, the yield of Sakukei 4 was higher in the LP-100 plot than in the urea plot, whereas that of Enrei and En1282 did not differ between the two fertilizer plots. A comparison of yield among the three genotypes revealed that the yield of Sakukei 4 was less than that of Enrei but higher than that of En1282, reflecting the difference of dry weight at flowering and seed filling stages. These results indicate that, for maximizing the yield of Sakukei 4, the utilization of controlled nitrogen release fertilizers such as LP-100 is effective to some extent, but the effect is not substantial and other agronomical measures to enhance growth need to be taken.
