42 MAIZE 



CHAP, which have chiefly winter rains ; the areas of very low rain- 

 fall such as the Karroo ; areas where there is a deficiency in 

 the spring rains, or where the intervals between rains are too 

 great, as in parts of the south-western Transvaal and western 

 Orange Free State ; and the higher mountain ranges where, 

 though the rainfall is ample, the growing season is too short. 



30. Sunshine. — The maize plant is especially suited to 

 the treeless grass-steppes of upland plateaux, and also thrives 

 in open "bush" country. But it does not seem at home in 

 humid, shady, tropical forests. Sagot (1) shows that maize 

 does not thrive in the warm, damp climates where manioc 

 {Manihot spp.) is grown, and De Candolle (1) supplements 

 this observation by pointing out that forests are generally un- 

 favourable to the production of any annual plants. 



The latter view seems in harmony with the general geo- 

 graphical distribution of cereal crops in the tropics. Major 

 Whitlock (1) observes that guinea corn (Sorghum vulgare 

 var.J, an annual plant, is the staple cereal of the natives on the 

 plains of Nigeria, at about 1,400 feet above sea-level, from Lake 

 Chad almost to the foot of the watershed plateau between the 

 Benue and the Cross Rivers. South of this plateau, however, 

 where the country is clothed with forest, no more guinea corn 

 is seen, the natives subsisting entirely on yams and plantains. 

 In parts of Uganda, also, bananas are more extensively grown 

 for food than any cereal. 



This is probably due, in the case of maize, to lack of sunshine. 

 It is noticeable in South Africa that in cloudy seasons, like 

 that of 1909-10, when there was nearly twice as much cloud 

 as usual during the months of January and February, the 

 maize crop is light. In continuous wet weather, pollination 

 appears to be retarded ; if the wet weather alternates with 

 warm sunshine at short intervals, pollination can take place 

 readily ; nature has provided that the silks shall be receptive 

 for a considerable period (sometimes as much as fourteen days 

 if pollen is not applied earlier), while the pollen supply ma)' last 

 for two to three weeks through a natural irregularity in time 

 of flowering of different individuals ; in one plant, alone, pollen 

 continues to fall for about four consecutive days. 



31. Influence of Climate upon ] r egetative Characters and 

 Time of Maturity. — Careful stud)' of the influence of climate 



