Effect of leaf cutting on physiological traits and yield of two rice cultivars

Field experiments were conducted during two summer seasons 2003 and 2004 to study the effect of leaf cutting on physiological traits and yield of two rice cultivars hybrid (H5) (IR 70368 A /G 178) and inbred rice. The leaf cutting was followed from flag leaf as follows: 1.)  L; Control = without leaf cutting, 2.) L1; flag leaf cut, 3.) L2; second leaf cut, 4.)  L3; third leaf cut, 5.) L4; both flag leaf and second leaf cut. 6.) L5; flag leaf, second leaf and third leaf cut together. A split plot design with four replications was used; the main plots were devoted to the cutting of leaves, while the sub-plots were assigned to the two rice cultivars. Chlorophyll, sugar, starch and grain yield parameters were severely affected by L5, followed by L4, L1, L3 and L2 in sequence. However, as a single component affecting maximum to these parameters is the removal of flag leaf. The flag leaf contributed maximum to the yield of rice grains. L5, L4, L1, L2 and L3 treatments grain yield (relative % of control) by 59.87, 94.92, 44.89, 29.58 and 19.98 % respectively. Flag leaf contributed to 45% of grain yield and is the single most component for yield loss.The contribution of leaf removal in hybrid rice was minimum, suggesting the probability of maximum translocation of photosynthesis from stem to the grain during grain feeling stage of hybrid rice after leaf removal.   Key words: Rice, leaf cutting, physiological traits, yield and cultivars.