Variation Of Leaf Gas Exchange Capacity and Morphological Characters Of Leaf In Soybean [Glycine Max (L.) Merr.] Recombinant Inbred Lines.

Leaf morphology can be an attractive target of the genetic improvement of photosynthetic capacity. It has been suggested that E1 and Dt1 loci, or the vicinity of these regions involve in the variation of stomatal density (N_s) and guard cell length (L_g). A considerable variation of these morphological traits was detected among the recombinant inbred lines from a cross between ‘Stressland’ and ‘Tachinagaha’ (ST-RILs). Some of these lines showed variations in N_s and L_g with the same E1 and Dt1 genotypes as Tachinagaha. It seems that the morphological characters of leaves can vary also by some other independent factor than E1 and Dt1 loci, in these lines. In this study, we measured stomatal conductance (g_s) of these ST-RILs cultivated in the field (Typic Fluvaquent) and compared it with the theoretical potential of g_s (g_p) that determined from morphological characters (N_s and L_g), to examine if the morphological potential is realized under field conditions. The g_s was measured by porometer, and N_s and L_g was measured by the SUMP method at the top fully expanded leaves on main stem in the 6th-node stage (V6) and in the beginning of seed stage (R5), the g_p was determined. A positive correlation was detected between the g_p and measured g_s in V6, but not detected for the measurements at R5. In conclusion, the morphological characters and photosynthesis of leaves can vary also by some other independent factor than E1 and Dt1loci, but for selection of the leaf gas exchange capacity, the morphological characteristics of leaves can be applied at least as a primitive indicator.