302 NATURAL CROSS-FERTILIZATION IN INDIA. 



In addition to the five cases of natural crossing at Pusa 

 described above, a number of stray plants were found both in 1909 

 and again in 1910 in some of the larger plots originally grown from 

 one plant in 1906. As these strays differed from any wheats 

 grown at Pusa we are inclined to believe they were natural crosses. 

 Time and space did not permit us to grow them on and prove their 

 origin and they were accordingly thrown away. Natural crossing 

 in wheat undoubtedly takes place at Piisa to a small extent, but 

 its occurrence bears no comparison to the frequency of this 

 phenomenon at Lyallpur. 



It will be evident from the above that natural crossing in 

 wheat is far more frequent under the conditions obtaining on the 

 Canal Colonies of the Punjab than it is in Bihar. At Piisa five 

 cases have been proved. Two hundred and thirty-one cases were 

 proved by us at Lyallpur, and of these no less than two hundred 

 and twenty-six took place in 1907. In the dry climate of the 

 Chenab Colony wheat is grown entirely by Canal irrigation and is 

 usually watered at least twice after sowing, the last watering 

 taking place after the plants are in ear. Often before this last 

 irrigation the supply of water in the soil is so small that the plants 

 wilt during the hottest part of the day, the glumes open and the 

 stigmas are exposed to the air. Under such circumstances, in 

 the dry hot climate, natural crossing is easy and it is not surprising 

 therefore that it is so frequent. Experimental cultures might be 

 protected to some extent from natural crossing by more frequent 

 and even watering. Wheat-breeding will always be very difficult 

 at Lyallpur, and it will be necessary to bag the F^ generation at 

 least. Pure line cultures will have to be rogued every year and 

 frequently re -selected, and the trouble and difficulty of growing; 

 pure seed for cultivators will be considerable. 



In the damper climate of North Bihar where wheat is grown 

 without irrigation on high moisture retaining loams natural cross- 

 ing although occurring gives little trouble in selection and breed- 

 ing work. 



