J ^2 PERIODICITY IN THE GROWTH OF SUGARCANE 



been noted, in'parts of Bengal, that it is easy to put one's finger on the part of 

 the stem where the grouang cane experienced the onset of the monsoon rains, 

 whether because of differences of thickness and length of joints or the occur- 

 rence of abundant aerial roots. So too, the attack of a single moth-borer 

 leaves its mark in a sudden diminution in thickness and length of the joints, 

 rhose succeeding gradually recovering their normal size. The leaf scars of 

 many dicotyledons engrave the history of the year's growth on the stem 

 whether it be the slow growth of spring, when the scale leaves gradually 

 change i)ito foHage leaves, the putting forth of the branches, the rapid growth 

 in the summer or the slowing down in autumn. So too, although less evident, 

 there will be marks left in the joints of monocotyledons. My Assistant, 

 Mr. T. S. Venkataraman, has shown that, in some coconuts growing on the 

 Cane-breeding Station, there is periodicity in the vertical \\adth of the bases 

 of successive leaves, possibly connected with the seasons of the year, a fact 

 which receives additional interest from the periodicity recorded below in the 

 sugarcane itself. The mere study of the length of successive joints in a cane 

 may therefore sometimes be of use in indicating differing growth conditions 

 and some striking instances of this Avill be mentioned during the course of the 

 paper. But many other measurements have been made as well, from which 

 similar deductions could be made. 



The system of measurements employed is fully described, and numerous 

 examples are pointed, in Memoir No. 3,^ but a summary is here given 

 for the sake of clearness. As is natural, the chief importance is attached to 

 the growth in length of parts. Twenty canes are chosen to represent any plot, 

 safeguards being introduced to insure that they are average healthy ones at 

 a distance from one another. These are first measured joint by joint as to 

 length of lamina, leaf sheath and joint, and the results are so arranged that 

 it is easy at any time to pick out the successive organs belonging to any one 

 cane of the twenty. By a system of averaging (the difficulties of which need 

 not detain us here), an ideal cane is built up for these twenty, and this is taken 

 to represent the particular variety grown at that time and place. The measure- 

 ments thus obtained are plotted out on squared paper and placed on record, 

 as the appropriate curves of length of successive joints, leaf sheaths and laminas. 

 Reference may be made to the curves alreadv shoM-n of Khari leaf sheaths 



1 Barber, C. A. Studies in Indian Sugarcanes, No. 3. The classification of Indian canes 

 with special reference to the Saretha and Sunnabile gr.mps. Mem. Dep. Agric Inch, Bot. iSer., 

 Vol. IX, No. 4, May, 1918. 



