Effect of Growth-Regulators on Germination (Axillary Bud Growth) and Root Development of Sugar-Cane Stem Cuttings

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Abstract
1. Experiments were conducted to determine the effects of growth-regulators on germination and root development in cuttings from two varieties of sugar cane, Canal Point 36/105 and C.P. 36/13. The cuttings were partially or completely immersed in aqueous solutions of the growth-regulators before planting. 2. Although root development in sugar cane was favored by such treatment, the magnitude of response differed with varieties. In general, both indoleacetic acid (IAA) and the amine salt of alpha-ortho-chlorophenoxypropionic acid (alpha-O-CPA) were effective, the latter being more so than the former. 3. Synthetic auxin concentrations which gave maximum rooting responses generally limited the germination of buds. A concentration of 10 p.p.m. for alpha-O-CPA, and of 100 p.p.m. for other materials, seemed to be optimum for both responses. Alpha-O-CPA was found to inhibit germination more than did IAA, whereas a mixture of the two, in the ratio of 1:9, tended to mask shoot inhibition and was suitable also for root growth. 4. Treatment of the whole cutting was superior to treating only the 1-inch basal portion. Complete immersion would facilitate the treatment of a large number of cuttings on a practical basis. 5. There was evidence of a "stalk-position effect" in the response of sugarcane cuttings to growth-regulators. Cuttings from the middle portion of the stalk were found to respond best in germination as well as in root development. 6. Multiple-budded cuttings gave less root growth than one-budded cuttings. Since single buds responded best, the present practice of sugar-cane propagation should be more critically investigated, particularly in light of the fact that under, present practices about 1 acre of stalks is required to propagate 6 new acres. 7. An antagonism of shoot and leaf growth on root development was noted. Interaction of these factors was shown by statistical analysis. 8. Adventitious roots were induced on the intact nodes of growing stems of C.P. 36/13 by the application of synthetic auxins in lanolin paste. One per cent IAA was more effective than 0.1% alpha-O-CPA or a combination of the two.