Yield advantage of a ‘slow‐’over a‘fast‐’respiring population of Lolium perenne cv. S23 depends on plant density

SUMMARY Selected populations of Lolium perenne have previously been shown to have contrasting rates of mature leaf dark respiration and yield. Plants were now grown in high‐ and in tow‐density stands. We were able to reproduce the differences in yield for the high‐density‐grown plants. However the low‐density‐grown plants did not differ in yield and so (the correlation between respiration and yield is not apparent, It is concluded that the difference in respiration rate is not the most important factor determining yield with these populations.