Abstract: Seventeen inbred lines and ten hybrids of maize were used to study the difference of stomatal resistance (RS) among genotypes and its relationship with photosynthesis (PH), transpiration (TR) and water use efficiency (WUE) under different photosynthetic photon flux densities (PPFD), leaf positions, growth stages and source sink ratios. The results indicated that there was a significantly difference of RS among different inbred lines, with the maximum of 2.3 times difference. Reducing PPFD, increasing the difference of leaf positions, postponing growth stages or changing source sink ratios could iuduce an increase of RS value. The variation of RS would correspondingly result in the change of TR and PH. There was a significant negative relationship of RS with PH and TR and the coefficient was r_RS-TR>r_RS-PH. The relationship between RSand WUE was erratic.

Key words: Maize, Stomatal resistance, Photosynthesis, Transpiration, Water use efficiency, root length, root surface area, yield, tillage practice