The cotton plant in Egypt, studies in physiology and genetics . made by these methods have given dataof which the following series is representative :— Length of true root. Sown March 28 ... 0 Measured .., April 2 6 cm. ,, ,, 4 14 cm. ,, May 15 55 cm. ,, ... Julyl ... 140 cm. (aht.) ,, September 1 ... ... 220 cm. 4- From tliese it follows that the root-depth in well-drainedsoil certainly reaches two metres by the end of August.* * The lower soil-temperature in the Northern Delta should diminisli theroot-extension considerably. The point needs investigation on account ofits intim
The cotton plant in Egypt, studies in physiology and genetics . made by these methods have given dataof which the following series is representative :— Length of true root. Sown March 28 ... 0 Measured .., April 2 6 cm. ,, ,, 4 14 cm. ,, May 15 55 cm. ,, ... Julyl ... 140 cm. (aht.) ,, September 1 ... ... 220 cm. 4- From tliese it follows that the root-depth in well-drainedsoil certainly reaches two metres by the end of August.* * The lower soil-temperature in the Northern Delta should diminisli theroot-extension considerably. The point needs investigation on account ofits intimate relation to drainage projects. 38 THE COTTON PLANT IN EGYPT chap. Lastly we have to consider an abnormal limiting factorof root-growth, namely deficiency of soil-oxygen, usuallydue to water-logging of the minute interstices which thesoil contains. Owing to the fact that its anatomicalstructure does not include an elaborate system of inter-cellular air-spaces, such as aquatic plants possess, thecotton root is locally asphyxiated in water-logged soil, and. Fia. 37.—Water Jet Excavation of Roots. See Fig. 35 on which the area of this photograph is marked. Lateral from neighbouring plant on right is marked with an X. Length, 170 cm. +. in a few weeks even the stout, woody roots are not merelydead, but decomposed. Here also we require preciseinformation as to the degree of soil saturation whichproduces these effects under field conditions, but the mainfacts are perfectly clear, and we shall meet with the seriouseconomic effects of this root-asphyxiation at frequentintervals. The stomata.—Certain plant physiologists have AND ENVIRONMENT 39 expressed doubts asto the importanceof the stomata inregidating transpir-ation, 1)111 such iscertainly theirfunction in thecotton plant. Con-sequently, an ex-amination of thestomatal move-ments, so far asthey are at presentknown, is necessaryto an understand-ing of the way inwhich the stemloses water. The stomata ofEgyptian c
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Keywords: ., bookcentury1900, bookdecade1910, bookidcottonplanti, bookyear1912
