Net Photosynthetic Rates, Relative Leaf Growth Rates, and Leaf Numbers of 22 Races of Maize Grown at Eight Temperatures¹

Abstract

Twenty‐two races of maize ( Zea mays L.) and one selection of teosinte ( Euchlaena mexicana Schrad) were grown under natural daylight in eight glasshouses where day/night temperatures were maintained from 15/10 to 36/31 C. Differences were found among temperatures and races in net photosynthetic rates, relative leaf growth rates, and leaf numbers. At low temperatures, high altitude races had relatively higher leaf growth rates and dry weights at harvest. At high temperatures high altitude races had relatively lower net photosynthetic rates. Leaf numbers increased with increasing temperatures.