Comparative analysis of leaf vein density in Sri Lankan traditional rice varieties

The C3 photosynthetic pathway of rice is less efficient than the C4 pathway. The possibility of conversion from C3 to C4 pathways in rice is currently under experiment. In plants undergoing such a transition, higher leaf-vein densities (LVD), and development of Kranz anatomy is expected to be present at an initial stage. High LVD could exist among traditional rice and those could be used as a starting point towards developing C4 rice. In the present study, LVD (estimated by average vein length between, two large longitudinal veins (LLV), two small longitudinal veins (SLV), and the vein length per unit area (TLV)) of 23 Sri Lankan rice accessions were analysed by performing a one-way ANOVA, with mean separation using Duncan’s multiple range test. Among the tested varieties LLV, SLV, and TLV were found to be significantly (p<0.05) different among accessions. Based on the mean separation, the highest LLV was shown by Thanthiribalan, and the lowest by Dewareddhiri, Mahasuduwee, Suwadel and five other accessions. The highest SLV was reported in three accessions and the lowest was in Mahasuduwee, Suwadel and Mahakuruwee. The highest TLV was reported in Mahasuduwee, Suwadel and Mahakuruwee and the lowest in IR 64. Unlike TLV estimation, SLV can be measured directly. Given that TLV and SLV are negatively correlated (r=-0.9183) a low SLV will be a suitable parameter to select for high TLV. The accessions, Mahasuduwee, Suwadel and Mahakuruwee carried a higher LVD (lower SLV and LLV leading to higher TLV) and can be recommended as candidates for studying C3 to C4 photosynthetic pathway conversion in rice.