Abstract
Selecting for digestibility by the observation of some plant characters is easier than chemical analysis if those characters are associated with digestibility. This experiment was intended to investigate the relationship between in vitro digestibility and some morphological and physiological traits in hay of space-planted orchardgrass. Characteristics were investigated for leaf color, leaf width, leafiness, growth habit, leaf flexibility, date of ear emergence, spring vigor and in vitro digestibility (Table 1). Digestibility of individual plant was analysed at heading stage by the one-step cellulase method (J. Japan. Grassld. Sci. 23, 177-182, 1977). Significant difference was observed when digestibility of eight varieties were compared with the mean (n=91-97 plants). Variety difference between the highest (Okamidori) and the lowest (Kitamidori) was 3.6%. Range of digestibility for 758 plants was 20.0% (Table 2). In the relationship between in vitro digestibility and plant characters, the trends differe in different varieties. Higher digestibility plants showed lighter leaf color in Okamidori, greater leaf width in Okamidori and Pennlate, and prostrate form in Akimidori, Chinook, Tammisto and Tenderbite. Plants showing earier ear emergence indicated high digestibility in Chinook and Pennlate but low digestibility in Akimidori and Tammisto (Table 4). Using 758 plants, greater leaf width, later ear emergence and prostrate form were correlated positively with high digestibility (Table 4).
