176 CHAPTER XI 



plant breeder, the farmer can do a good deal to improve his 

 crop. Once he is assured that the variety he is growing is the 

 most suitable one for his locality, he should proceed to select 

 the best plants, having regard to yield, length and strength of 

 staple, number of bolls, storm resistance, early maturity, uni- 

 formity and disease resistance. A certain percentage of cross- 

 pollination takes place between plants situated close to one 

 another. Consequently varieties should be kept widely 

 separated. Hybrids are often abnormal in vigour of growth, 

 therefore in selecting plants it is well not to select those 

 showing abnormal growth. Once a desirable type has been 

 obtained, the grower might proceed in two ways. Firstly, 

 he might grow half the seed from each plant in a row test, and 

 if the progeny is uniform and thus pure to type, he should grow 

 the remaining seed in an isolated plot. The seed from this 

 should be increased by growing it in an isolated plot until sufti- 

 cient seed is procured to plant the acreage required for the main 

 crop. In the second method he might practice a rough form 

 of mass selection, i.e., select a number of desirable plants each 

 year, the seed from which he would plant separately until he 

 had sufficient from this to grow his general crop. 



Climatic Eeqcirements. — Burkett^ states these to be as 

 follows: — " A relatively high temperature; a long growing 

 season ; a moderate and well distributed rainfall throughout the 

 growing season ; a small amount of rain at the maturing period ; 

 a great deal of sunshine." In South Africa these conditions 

 are well met in many areas of low altitude in the Transvaal, 

 Swaziland, Zululand and Natal. 



A comparison of the temperatures prevailing in our 

 potential cotton areas with those found in the American cotton 

 belt show a distinct advantage to the South African cotton 

 grower, since the extremes are not so great as those of the 

 American cotton belt. 



An examination of the minimum temperatures occurring 

 in our cotton parts indicate a frostless season sufficiently long 

 for cotton. In some areas unusually early frosts, which tend 

 to limit the crop, may occur in April. 



The following records, the average of a number of years, 

 show the average of the minimum and maximum temperatures 

 obtaining at the places mentioned. It must be noted that the 

 altitude of the towms Zeerust and Eustenburg is considerablv 

 higher than the suitable areas for cotton of Marico and Eusten- 

 burg districts : — 



