RICE 621 



Natural crossing is known to have occurred in rice, 

 particularly the crossing of cultivated and red rices. 

 At Dacca in India, natural cross-pollination is said to 

 have occurred to the extent of 4 per cent of the flowers. 

 On the other hand it has not yet been observed in the 

 pure line cultures at Nagpur (Graham, 1913, p. 214). 

 Two interesting correlations between length of stem and 

 tillering, and between length of stem and weight of 

 panicle, have been determined by Kikkawa (1912, pp. 

 18-19), which may be of use in hybridization work. 



CULTIVATION 



692. Soil adaptation. Apparently the best soil for 

 rice is a medium loam or clay loam having 50 per cent 

 of clay and an impervious subsoil. The drift soils of the 

 Texas-Louisiana gulf coast are well adapted. Extreme 

 heaviness and stiffness of soil are always better than 

 extreme lightness and porosity, partly because of the 

 greater amount of plant-food usually in the former, and 

 particularly because of its ability to retain water. The 

 " buckshot clay " soils of southeastern Louisiana and the 

 " adobe " soils of the Sacramento Valley, which are ex- 

 cellent rice soils, are so stiff that they are plowed with 

 great difficulty before flooding, and are exceedingly 

 tenacious and putty-like when wet. Rice will do well 

 in soils that possess a considerable quantity of alkali, 

 a fact no doubt largely accounted for by the flood- 

 ing, which keeps the alkali in dilution, so it is never 

 deposited at the surface at a time when it can injure 

 the crop. 



693. Fertilizers. If the straw, chaff, and stubble of 

 the rice crop are afterward plowed under, it does not 



