VARIATION IN STOOL ARCHITECTURE AND BUD SPROUTING: MORPHOLOGICAL TRAITS THAT MAY CONTRIBUTE TO RATOONING

PROFITABILITY IN THE sugarcane industry is measured on cane yield (TCH) and sucrose content (CCS), with improved profit margins with every extra year of ratoon growth. A major component for the success of a ratoon crop is the recruitment of basal stem buds and growth into mature stalks. We have established methods to measure traits for bud outgrowth that allow comparisons between genotypes. These traits include bud number, bud viability and ability to sprout, in relation to the position in the stool. The results have identified variation between several sugarcane genotypes. When stalks or billets are planted for establishment of sugarcane crops, axillary buds located at the nodes each give rise to a single stalk. Secondary tillers (‘b’ stalks) then arise from buds on the underground internodes of the primary stalk. These may give rise to third order tillers (‘c’ stalks) and so on, generating a complex branched structure of underground stalks and associated roots termed a stool. While all of the varieties sprouted ‘b’ stalks from the basal section of the primary stalks from which they originated, some were also recruiting stalks from the buds higher in the profile. Similarly, there were differences in the underground branching, with some varieties restricting growth to ‘b’ stalks, though others expanded to ‘c’ stalks. These traits have identified variations in the stool architecture that influence the growth of the plant and ratoon crops and may be useful to assess genotypes for ratoonability potential in the future. The study of sugarcane ratooning will be assisted by the adoption of a systematic nomenclature and classification to characterise the generations of stalk recruitment.