Effects of early drought and transplanting on the subsequent development of the tobacco plant

Abstract

Detailed studies were made of the growth of tobacco plants during and after the experimental imposition of water stresses similar to those of commercial hardening and transplanting. During water stress (due to root damage, drought, or both) all growth rates were depressed, but, a short time after the relief of stress, relative leaf expansion rates, net assimilation rates, and relative growth rates rose to higher values than were reached by untreated plants at comparable stages of development. As a result, all stressed plants rapidly recovered from their period of adverse conditions. The plants that had originally been subjected to the most severe treatments overhauled those that had suffered less and finally acquired the greatest total leaf areas and dry weights. The increase was due to: (1) a change in the distribution of leaf surfaces, which occurred when leaf initiation was retarded relative to leaf expansion and resulted in increased growth of the lower leaves; (2) a delay in flower initiation, which took place at a higher node, increased the number of leaves, and prolonged the period of vegetative growth.