The superokra leaf gene and short-season cotton breeding

Abstract

The performance of superokra leaf backcross progenies was compared with their normal leaf recurrent parent in two experiments in two successive seasons at Narrabri Research Station in the Namoi River Valley of New South Wales. The first experiment used standard 1 m row spacing and the second both standard and twin-row spacing (two rows sown 25 cm apart on 1 m beds). Other varietal comparisons including short-season and standard types, and normal and superokra leaf types were also made. The mean yield of 220 superokra progenies was 8.4% less than their recurrent parent in the first experiment. The mean yield of 14 of these was 1.2% greater in the second experiment. The superokra leaf progenies were earlier maturing and had a higher lint percentage. Strength and fineness of the progenies compared with the parent varied between experiments. Although mean staple length of the superokra leaf progenies was shorter than the recurrent parent it was demonstrated that selection for longer staple without yield sacrifice was feasible in the backcross population. All short season varieties tested had deficiencies of yield or quality compared with desired standards. The normal leaf Tamcot SP-37 and the superokra leaf M8 variety appeared to have the best combination of earliness and other attributes. There were no significant variety interactions with row spacing. Further study is needed to clarify the usefulness of the superokra leaf gene, because of quality deficiencies and apparent greater instability of varietal performance associated with the gene.