Makonnen, Dejene (PhD)Debelo, Aberra2018-07-262023-11-182018-07-262023-11-181982-05http://etd.aau.edu.et/handle/12345678/10139A study of dry matter accumulation and N, P distribution and , ther agronomic characters was conducted on two hybrids of maize (Zea mays ~.) and their parental lines. Highly s i gnificant di fference was observed in total and ear dry matter accumulation among the genotypes, the growth stages and growth stage by genotype interacti on. The highest t otal and ear dry matter were produced a t the final stage of maturity. The analysis of l e af and stalk dry ma tter indicated that there was highly signj f '_'Oant difference among genotypes and growth stages. Howevere, there was no interaction. I n general a decreasing tendency of dry matter accumulation was observed in the non grain part as growth stage advancences. This loss is assumed to be due to trans location of carbohydrat~ B t o the grain late in the season as grain development advances. The associa tion bet ween l eaf number and total dry matter production was found t o be positive and significant (r= 0.86). 31 .4% and 68.6% averaged over all the geno types was grain and non grain , respectively. The transl ocati on of shoot dry matter into the ear indicated that H611 and its parental lines are more efficient than S.R. 52 and its parental lines. Highest harvest index of 0.44 and 0.43 was produced by H611 and SR52 , respective ly. Further more, an increasing and a decreasing trend of dry matter production was obs erved in the different plant parts as growth stage advances e xcept for the ear and ' grain . From this study it could be suggested tha t, Parental lines which .. L are effic~nt i n production and distribution of dry matter should be included in future breeding program t o produce high yi e lding hybrids.: The differences observed in the production and translocation of dry matt er aft e r flowering suggested that genotypes having such characters are very impor tant. Eventhough, it is imposible to point out a particular growth stage a t which hybrid vigor is expres ssed , insect pests , diseases , moisture and mutri ent deficienci es which affect the rate o f l eaf development should be ~void e d· inorder to have a healthy plant growth for muximum yie ld production.enDistribution by twoma MaizThesis