Evaluation of promising forage maize hybrids under Markazi province climatic condition

Introduction: Forage maize (Zea mays L.) is one of the important and strategic crops in Iran, which, as a fodder for livestock production systems, makes a major contribution to providing human protein nutrition requirements, especially red and white meat. In recent years, the area under cultivation of forage maize has increased (Ashofteh Bigrami et al., 2010; Mojab Ghasroddashti et al., 2017; Khavari Khorasani et al., 2010). Therefore, the aim of the present study was to identify and introduce promising forage maize hybrids that could be an alternative for commercial hybrids under Markazi Province climatic condition.
Materials and Methods: In order to compare and evaluate ten new and promising forage maize hybrids (H1, H2, H3, H4, H7, H8, H9, H10, 89MAY70 and HIDO) and two foreign commercial hybrids (KSC700 and KSC704) in terms of fresh forage yield, phenological and some morphological traits related to forage yield, the experiment was conducted in a randomized complete block (RCB) design with four replications during two years (2014 and 2015) at Arak Research Farm of Agriculture and Natural Resources Research Center in Markazi province. The experimental measurements included number of days to pollination (DTP), number of days to silking (DTS), anthesis-silking interval (ASI), number of leaf (No. leaf), stem diameter (SD), plant height (PH), number of ear per plant (No.ear.plant-1), fresh ear yield (FFY), fresh forage yield (FFY) and ratio of FEY to FFY. All data were subjected to analysis of variance (ANOVA) using the GLM procedure of SAS statistical program. Principal component analysis (PCA) was conducted to identify the interrelationships between the forage maize hybrids and all the measured traits and the biplot was drawn using the Stat Graphics software (ver.16.1.11).
Results and Discussion: The results showed that the differences among hybrids were significant in terms of the measured traits (P<0.01). However, for most traits, significant variations were observed, except for SD and No.ear.plant-1. The lowest variation among the studied hybrids was related to ASI and, the greatest variation was associated with DTP, DTS and ratio of FEY to FFY. The fresh forage yield performance as a resultant of the measured traits showed that hybrid H4 and HIDO had the highest (85316 and 84964 kg.ha-1, respectively) and hybrid H8 had the lowest (65751 kg.ha-1) fresh forage yield. On the other hand, results of principal component analysis revealed that the first two components explained 67.40% of the total variation. The first PC (PC1) accounted for 37.94% of the total variation and had negative correlations with FFY (-0.52), No. leaf (-0.37), and PH (-0.37). Nevertheless, it had positive correlation with ASI (0.48). PC2 explained 25.66% of the total variance and had a high positive correlations with ratio of FEY to FFY (0.53), FEY (0.49) and No.ear.plant-1 (0.49). To classify the hybrids based on the PCs, the biplot of PC1 and PC2 was constructed. Clearly, the promising hybrid HIDO formed a single group characterized by high FFY, FEY, ratio of FEY to FFY and short ASI. In contrast, the promising hybrid H8 and H10 exhibiting a long ASI and high ratio of FEY to FFY and lower value of FFY formed a distinct group. Other promising hybrids with commercial control hybrids (KSC700 and KSC704) were classified as intermediate in terms of the measured traits; nevertheless, the promising hybrid H4 belonging to this group was remarkable for the measured characteristics, which demonstrated a high similarity with hybrid HIDO. In general, the promising hybrid HIDO and H4 had the highest forage value in terms of quantity and quality; while the promising hybrid H10 and H8, despite the high quality of forage, were not desirable in terms of FFY.
Conclusion: In general, the promising hybrid HIDO and H4 may be suggested as preferable and superior hybrids for further studies on the sustainability and compatibility of forage yield under climatic condition of Markazi Province. On the other hand, considering the importance of ASI as the main indicator for selection of resistant cultivars in areas under drought stress, it seems that two promising hybrids, i.e. HIDO and H4 with the shortest ASI could also be considered as preferable hybrids in the breeding programs under drought stress condition.