Response of Maize Cuitivars to Different Management Regimes

Abstract

Two field experiments were carried out at the Agricultural Experimental Farm of Alexandria University, during the two summer seasons of 1996 and 1997. Each experiment included sixteen maize (Zea maize, L.) cultivars consisting of eight single crosses, seven three-way crosses and one synthetic open-pollinated cultivar. The studied treatments included Four management regimes. These were; 40,000 plants/ha + 150 Kg N/ha, 60,000 plants/ha + 150Kg N/ha, 40,000 plants /ha + 300 kg N/ha and 60,000 plants /ha + 300 kg N/ha. Split plot design in three replicates was used.The obtained results showed that , grain yield and most of its components were highly significantly affected by the management regimes. The top yielding regime was (60,000 plants/ha + 300 kg N/ha)) with an average across the two seasons of 9.33 t/ha, in comparison with 4.47 t/ha for the low yielding regime (40,000 plants/ha + 150 Kg N/ha). The other two studied regimes were intermediate in grain yield.The maximum grain yield obtained from (60,000 plants/ha + 300 Kg N/ha) regime was mainly due to its high number of plants/ha which reached at harvest about 150% of that obtained with 40,000 plants/ha. However, that increase in number of plants was associated with a slight decrease in yield components namely; number of ears/plant, kernel weight and ear size (length x diameter). This study obviously indicated that maize hybrid, S.C.10. was consistently the top yield one in the two seasons, while the high yielding hybrids, S.C. "Bachear 13", S.C. 124 and S.C. 129, Fluctuated in their rank across the two seasons. The high yielding hybrids were characterized by heavier kernel weight and larger ear size (length x diameter).Although the interaction between cultivars and management regimens was significant, this interaction did not effect the rank of the cultivars. The correlation coefficient between the mean yield at the eight environments ranged between 0.883 to 0.987 and were highly significant from zero. This would indicate that cultivar rank was consistent at the eight environments. In the future one regime would be enough to predict the yield potentiality of the different cultivars. The significant interaction might be due to magnitude of the different between the cultivars rather than their rank. The recent results would suggest that regime 4 (60,000 plants/ha + 300 kg N/ha) would be recommended for the evaluation of the cultivars for both the high and low productive level.