STUDIES ON THE PROTEIN AND AMINO-ACID COM POSITIONS OF MAIZE HYBRIDS

As the result of the maize breeding in progress at the Agrargazdasag C o. Ltd., Debrecen, two single cross hybrids (De SC 351, De SC 377) and one triple cross hybrid (De TC 382) were entered for variety trials a t the Hungarian Institute for Agricultural Quality Control (OMMI) in 1 994. The crude protein content and tile ratios of 17 amino acids in th e grain yield of these these hybrids, of the parental lines and the st andard, Julianna SC (340), were studied in 1995 and 1996. The essentia l amino acid index was also calculated and analysed for the hybrids an d the parental lines. The results can be summarised as follows: The re sults of small plot comparative variety trials carried out by OMMI for three years indicate that all three hybrids had grain yields 6-10% hi gher than the average for the standards. Amino acid analysis on the cr ude protein of the maize grain showed that the quantities of some amin o acids vary to a certain extent from year to year, while others maint ain a stable value. Some amino acids were present in larger quantities in the hybrids than in the standard. It is worth noting that, with th e exception of the hybrid De SC 377. the order of the three limiting a mino acids (CYS, MET, LYS) was the same in both years for the other hy brids as regards quantity. In the hybrids De SC 377 and Dc TC 382, CYS and MET were found in higher quantities than in the standard. The ami no acid contents of the parental lines were only studied in 1990. It c ould be seen that the higher amino acid content of the parental lints was also perceptible in the hybrids developed from them. The contents of the three limiting amino acids and the crude protein content were h ighest in the hybrid De SC 377 compared to the standard over the avera ge of two years. This is correlated with the higher amino acid and cru de protein contents of the parental lines from which the hybrid was de veloped. The protein yield of the hybrids was 1.03-1.06 t/ha averaged over two years, 6-9% higher than that of the standard. Julianna SC, Th e yield of cysteine was 10% higher than in the standard for Dr SC 377 and 7% higher for Dc TC 382. The methionine yield exceeded that of the standard by 20% in the case of Dc SC 377 and by 34% in De TC 382. The value of the essential amino acid index in the hybrids was 53-59% tha t of egg-white. The highest value was measured for De TC 382 in 1995 ( 59.14%), followed by Dc SC 377 with 57.5%. In 1996 the following order was observed: De TC 382 had the highest essential amino acid index (5 3.38%), followed by De SC 377 (56.13%) and De SC 351 (55.83%). The low est value was recorded for the standard, Julianna SC (54.08%). Among t he parental lines, De 6 had the highest E.a.i. value (53.66%), followe d by De 10(44.44%). The hybrid with the E.a.i. value, De SC 377, was c reated by crossing these two lines. It can be seen from the results th at in the course of selection the protein content and the protein qual ity can be improved to a certain extent without a loss in yield potent ial.