THE IMPROVEMENT IN THE YIELD OF INDIAN WHEAT. 191 



IV. Hybridization. 



Besides selection there is another method hj which the kinds 

 of wheat grown in India can be improved, namely, hybridization,, 

 or the application of the principles which have been founded on 

 the work of Mendel. By means of this method, it is possible to 

 create new wheats combining the desirable qualities of both 

 parents. Hybridization has greater possibilities than selection, 

 but on the other hand the process is laborioiis and time consum- 

 ing as the production and testing of a new wheat hybrid . cannot 

 be done under four years. 



Hybridization like selection is only possible after the separation 

 of mixed wheats into their ultimate constitiients. In modern 

 wheat breeding it is desirable to use for crossing only pure lines, 

 i.e., the progeny of single plants. It frequently happens when 

 a wheat mixture has been resolved into its constituents that all 

 the desirable qualities are not found in any one wheat. Thus 

 some wheats, characterised by high-yielding capacity, may be 

 defective either in quality, in resistance to rust or in strength of 

 straw. Others, on the other hand, may possess these latter 

 characters, but may give poor yields. It is in prodiicing new 

 wheats, perfect in all respects, that hybridization as a method of 

 improvement has its value. 



Passing over the inheritance of ordinary morphological charac- 

 ters of wheat, such as the presence or absence of beards, colour of 

 the chaff and grain, and so on, the characters of special value in 

 wheats are quality of grain, yielding power, strength of straw and 

 resistance to rust. It is found in breeding that all these qualities 

 and their opposites behave as unit characters and pass over as a 

 whole to the various hybrid generations. For example, when a 

 rust liable and rust resistant wheat are crossed, the plants of the 

 first hybrid generation are all rust-liable like one of the parents. 

 In this generation the rust resistant character of the other parent 

 is latent or recessive. Rustiness, on the other hand, is said to be 

 dominant. In the second generation, however, splitting takes 

 place in the proportion of three rusty plants to one rust-resistant 

 plant. These latter in succeeding generations breed true as. 



