Selection criteria in grass breeding. VI. Effects of defoliation on plants growing in small plots in field and controlled environment conditions

Abstract

1. This paper reports on two experiments, one conducted in the field, the other in a cold cabinet. These had three objectives: (i) to examine the effects, on yield and some components of yield in certain grass varieties, of various combinations of frequency and intensity of defoliation, (ii) to compare these effects in the two environments, and (iii) to assess the value of very small plots.2. Records were taken of the major environmental variables in the field; the chosen environment in the cabinet was quantified.3. In the field trial, the cutting treatments comprised all combinations of two frequencies (herbage cut when 8 in. and 4 in. in length) and two intensities (cut back to tiller lengths of 2 in. and 1 in.) plus a fifth treatment of cutting at a silage stage back to a tiller length of 1 in. The first four treatments were also used in the cold cabinet trial. S170 and North African tall fescue were common to both experiments; in addition, S22 Italian rye-graes was included in the field trial. In both trials, plots consisted of four rows of seven plants, square planted at 2 in. x 2 in.