plants had very poor root system consisting of small and shallow roots (Figure 2). At 4 weeks, these plants had a root mass which was about only 14%, and root length and volume which were less than 50% of those in seedlings growing in the unprotec- tive environment. Furthermore, when these plants were transferred to the unprotective environment, very little root growth occurred during the first 3 d followed by a significant increase up to 7 d. However, consistently during this period, plants grown continuously under the unprotectiveenvironment showed better root growth. The results, thus, indicate that plants grown under the protec- tive environment are generally sensitive to normal growing conditions found in a growth chamber