58 
Indian Forest Records. 
[Vol. VIII 
When moisture and temperature, therefore, are suitable for the 
continued growth of the radicle, the latter, instead of 
penetrating vertically downwards into the soil, develops 
horizontally between the layers of leaves. In conse¬ 
quence of this the plants die from drought as soon as the 
dead leaves and surface soil dry out, see present paper, 
para. 12 (2) (7). 
(c) an injurious action which comes into play after the radicle 
has penetrated the soil and which is provisionally ascribed 
to bad soil-aeration. It directly causes an appreciable 
number of deaths and diminishes root growth. It is 
active in sal forest loam which is kept moist but is inopera¬ 
tive in clean sand, see present paper, paras. 14, 15, 18, 
19, 20 (1) and Plate II. 
(7) Burning oh the layer of dead sal leaves in the forest does greatly 
improve germination and increases the number of seedlings 
which survive. While not materially diminishing the 
number of seedlings which were on the ground before the 
burning, the latter appears to reduce the height growth of 
such seedlings, see Ind. For. Rec. V, 4, part II, 1916, paras. 
33, 42 and present paper, paras. 22, 23 (7), 35, 36, 37 (2), 
39, 40, 41 (2). 
(8) With reference to the early growth of sal seedlings, soil-composi¬ 
tion is, in itself, a factor of comparatively little importance. 
Provided the water supply is suitable, sal seedlings will 
grow well without dying back on soils of widely different 
chemical and physical composition, e.g. sand, loam, and 
garden leaf-mould, see Ind. For. Rec. V, 4, part I, 1914, 
paras. 12 (4), 32, and Appendix I. 
(9) Soil moisture, however, is a limiting factor of great importance. 
In the experiments carried out at Dehra Dun, sal seedlings 
were found to die or die back from drought when the water- 
content of the soil in contact with their roots fell to 3 per 
cent, and below in sand or sandy loam, or to 10 per cent, 
and below in loam,* see l.c. part I, 1914, paras. 13, 14, 15 
* The soil moisture death-limit probably depends to some extent on the evaporating 
power of the air and the rate at which the plants are losing moisture by transpiration. 
It was impossible, at the time, to carry out a continuous record of these conditions but 
the experiments here referred to were carried out (a) under shade in the cold season 
and (6) in the open in the hot season, i.e. under widely varying conditions of evapora¬ 
tion. As the death-limit only varied by 1 per cent, under these conditions in one and 
the same type of soil, it is believed that the limits here reported are approximately correct 
for local conditions. 
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