The Production of theStrigaandOrobancheGermination Stimulants by Maize Roots

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Abstract
Six serial segments, each 3·0 mm. in length, have been excised from the tip backwards along the maize root and groups of each fragment have been aerated in water and in solutions of sugars for varying times. The amounts of the complex of Orobanche and Striga germination stimulants which accumulate in the culture fluids have been assessed and compared with the amounts initially present in the tissue at the time of excision from the root. It is shown that with each fragment more of the complex appears externally when sugar is supplied. 10−2 M. solutions of glucose, fructose, or sucrose promote an optimal effect. The amounts in the external solutions are inversely proportional to the initial contents of the segments. The first segment (0–3 mm.) contains the highest proportion of the complex initially, but when immersed in water or the sugar solution very little of it appears externally. The second segment (3–6 mm.) contains the least initial quantity of the complex but in water or sugar produces considerably more than any other segment and more than is originally present. As the series is traversed from segments 2 to 6, the segments have progressively larger initial contents than has segment 2, but after aeration in the sugar solutions the amounts accumulating externally are less than with segment 2 and decrease with their increasing distance from the root tip. The significance of these observations is discussed.