PLUMULE AND RADICLE OF RICE SEED. 



487 



sufficient quantity of water from a scanty source the radicle must 

 develop faster, (and produce more root hairs) to enlarge the 

 absorbing surface, than when there is abundant supply. We see, 

 however, when we examine the figures in each of the two experi- 

 ments and compare similar cases, that the ratio is seen to be more 

 or less different. Tin's fact is probably to be attributed mainly to 

 the difference of temperature in the two e.xperiments. 



It has been the custom in our country from remote ages to let 

 out the water of rice-fields in the morning, after the rice seeds have 

 been sown, and let it in the evening. One good effect of this 

 procedure is of course the warmtli imparted to the fields by sun- 

 shine in the daytime and protection from cold or even frost at night. 

 Another explanation of this procedure has often been sought in the 

 necessity of exygen during germination. Indeed, in the warmer 

 parts of our country, the contrary procedure is sometimes observed, 

 water being let in in the morning and let out in the evening. Where 

 the field has an inclination to dry out when the water is drained off, 

 there we observe that farmers are in the custom of draining off the 

 water when the seedlings are striking out the roots, saying that by 

 this means the roots become "firm." 



Now since as we have seen from the result of the above 

 experiments, rice seeds though covered with the water of irrigation 

 will not be much in want of oxygen but will freely germinate under 

 water, the explanation hitherto given as to the benefit of letting out 

 water in giving the oxygen to the germinating seed, must be 

 withdrawn. The true cxjjlanation is undoubtedly to be sought in 

 the benefit due to the acceleration in the growth of roots so neces- 

 sar)- to the normal development of the seedlings. Tluis it must be 

 suggested to the farmers to irrigate the field after sowing in such a 

 manner that water shall riOt be much more than sufficient to saturate 

 the soil till the seedlings sufficiently strike the rootlets into it, at 

 the same time avoiding tiic exposure of seeds to dryness, which of 

 course will greatly injure their germinating power. 



