Two field experiments were conducted at Shandaweel Agric. Res. Station in
Sohag, Egypt during 2002 and 2003 seasons. The aim was to identify the effect and
contribution of indMdual leaves removal from flag leaf through the 6 leaf and 7 leaf
to down (old Leaves) as well as control treatment (without defoliation). These
treatments were applied on two sorghum genotypes Dorado and Shandaweel 2
hybrid The obtained results indicated that removing any leaf from plant significantly
decreased head dry weight, grain weight/plant, fodder weight/plant, 1000 kernel
weight, number of grains/head leaves dry weight, stem dry weight and total biomass
compared to control treatment. The highest depressions percentage (DP) in head dry
weight, grain weight/plant, fodder weight/plant, 1000 kernel weight, leaves dry weight
and total biomass were observed with removing 7 leaf to down while number of
grains /head and stem dry weight were highest depressed with removing the 4 leaf
treatment. On the other hand, the contribution of leaf area unit (LUC) revealed that
the highest contribution displayed by the flag leaf followed by 2°- leaf in head dry
weight, grain weight/plant, fodder weight/plant, 1000-kernel weight, number of grains
/head and total biomass. While nearly equal LUC values were obtained in leaves dry
weight and stem dry weight by removing flag or 2 lear Whereas, the lowest LUC
values in head dry weight, grain weight/plant, fociuer weiht/plant, number of
grains/head, stem dry weight and total biomass by removing 7- leaf to down. Also,
removing 5 leaf gave lowest LUC values in 1000- kernel weight and leaves dry
weight. Shandaweel 2 hybrid ‘ias higher than Dorado variety in most growth and
yield traits. Partial regression coefficients were significant for grain number/head by
removing leaf, grain weight/head by removing each of flag, and 7 leave
to down, head weight by defoliation each of , 4g" and 7th to down and 1000-kernel
weight by removing each of flag, 2, 6th and 7hh leaves to down. Partial
regression coefficient was significant for fodder weight/plant while the reverse was
true for plant height.