A preliminary study of the effect of differences in local climate on the early growth of some crop plants in the southern region of Uganda.
Young plants of maize and cotton grown in sand culture were kept at 1 site either during the day or night, and placed during the remainder of each day or night at each of 4 sites on 8-12 successive occasions. The range in altitude between sites was 200 ft, and the difference in temperature between sites was less than 1°C during the day and 3°C during the night. Effect of day-site on plant dry weight was slight, though cotton plants were significantly smaller at the lowest site. Where night-sites were compared, maize plants were 17% smaller at the lowest than at the highest site. Dew at the lower night-sites appeared to have increased the size of cotton plants grown there by at least some 13%. NAR of cotton was lower at the lowest night-site than at the highest, but leaf-area ratio was not affected. It was concluded that the effect of local climatic factors on growth can be far from negligible even where variation in altitude is comparatively small.-R.B.