Evaluating the genotype × nitrogen fertilization interaction on the nutritive value of the first crop in timothy (Phleum pratense L.) clones
2012
Ashikaga, Kazunori | Tanaka, Tsuneki | Fujii, Hiroki | Deguchi, Kenzaburo | Iida, Kenji
Improvement of the nutritive value of timothy (Phleum pratense L.) through breeding should result in enhanced livestock productivity. This study evaluated the effect of genotype (G) × nitrogen (N) fertilization interaction (G × N) on the nutritive value of the first crop of timothy in northern Japan. Five traits, the contents of low‐digestible fiber (Ob), water‐soluble carbohydrate (WSC), mono‐ and disaccharides and fructan and the ratio of Ob to organic cell wall (OCW), were investigated as quality traits for 16 clones under three N rates (3, 7 and 11 g N m–2 as low, standard and high levels, respectively). The G × N effects were non‐significant in all the traits despite the significant main effects of G and N in all or most of the traits. Coinciding with this, there were significant correlations among the three N rates for Ob, WSC, fructan contents and Ob/OCW ratio. Correlations between the low and high N rates showed weaker trends than those between the standard and low N rates or between the standard and high N rates in three of the five traits. Fructan content showed small standard deviations and ranges, indicating the difficulty of using it as a selection index for evaluating the genetic variation. The results suggest that, for the Ob and WSC contents and the Ob/OCW ratio as the desirable traits, the relative ranking of genotypes is almost consistent across different N application levels and selections for the traits at the standard N level are of potential use for effective improvement of the nutritive value of timothy.
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