144 STUDIES IN INDIAN SUGARCANE SEEDLINGS 



has been carefully studied (c/. PI. VII and the text). The first indication of 

 the effect of salinity is seen in the yellowing of the leaves. An interesting 

 fact was noted in a batch of Saretha seedlings trans])lantcd direct from the 

 pans into the ground, when three months old. A preliminary separation was 

 made, at six months, between dark green seedlings and such as had light 

 green or yellowish green leaves, but the final examination was delayed for a 

 week, after which some of the dark green seedlings were noted to have become 

 yellow. There was heavy rain during the week. The cause of this was at 

 once understood, and may be explained by the cuiious effect produced by 

 heavy rain shortly before the Agricultural Conference met at Coimbatore in 

 1913. The field of cane varieties was healthy and dark green, when a couple 

 of inches of rain fell, and the whole field turned yellowish. After some study, 

 the following explanation was offered and this has been substantiated by 

 further observations. The slightly saline land, during irrigation in the trenches 

 had accumulated a layer of brown, powdery earth just above the point to 

 which the water reached, each ridge showing this layer distinctly at the 

 point where, presumably, evaporation was strongest (PI. XXVH). Ou 

 analysis, this powdery earth showed the presence of as much as 11% of salts, 

 chiefly sodium chloride, and the heavy downpour appears to have washed 

 the salt down to the roots of the canes with resulting yellowing. Any attempt 

 at classification according to the light and dark green colour of the leaves 

 of seedlings must be a})proached with caution. 



Coloration of the leaf sheath, other than that due to disease, is a well 

 marked distinguishing character in young seedlings, although it becomes 

 difficult later on. The sheaths may be pure green, although this is comj^ara- 

 tively rare. They are usually tinged with light purple, pink or a vinous 

 colour. Sometimes they are strongly violet or bluish purple or even a clear 

 pink, and a number of classes have been instituted according to variations in 

 the colour of the leaf sheaths, which is rarely constant in any batch of seed- 

 lings. The colour of the veiy small shoots, although depeiiding primai'ily 

 on the colour of the leaf sheaths, appears to be of a somewhat different 

 character. They are either green, purplish green, dark purple or sometimes 

 almost black. 



The colour of the transverse marks (the small triangular patches of colour 

 on each side at the base of the lamina where it joins the sheath) is easily seen 

 in young seedlings, and affords a useful separation charactei-. The colour 

 varies frpm very dark chocolate to purple, reddish and brown to wax coloured, 

 yellow, green and greyish white, the latter probably owing to bloom. 



