Maize is an important crop in Indonesia that is utilized for food, feed, and industry. Waterlogging is one of the abioticstresses challenging maize production in recent years due to climate changes. Vegetative-phase screening methods may benefitplant breeding programs because potential genotypes can be identified at earlier stage with lower cost. This study consistedof two experiments. The first experiment was carried out at the Sawah Baru experimental station of Bogor AgriculturalUniversity (IPB), Bogor, from June to September 2017 using an alpha lattice design with three replications and four blockswithin each replication. The second experiment conducted in a greenhouse at Cikabayan experimental station of IPB, Bogor,from December 2017 to January 2018 using a randomized complete block design with three replications. Genetic materialused were 21 maize genotypes from the Indonesia Cereal Research Institute (ICERI) and IPB, including 19 hybrids and 2inbred lines. The results showed that the dry root weight under normal conditions had significant positive correlation withgrain yield under waterlogging stress, and therefore is potential for early screening. Adaptive genotypes in waterloggingstress selected based on dry root weight are DKLx30, DKLx11, MGoldx37, MGOldx41, and IPB L15-1xMR14. Predictedmean yield across these genotypes was 0.57 ton ha-1 higher yield than the overall mean in waterlogging stress condition.Selected hybrids can be further evaluated for variety release.

ABSTRACT

Industrial demand for maize oil has been increasing and therefore corn breeding efforts began to focus on developing improved maize varieties with high oil content. The objectives of this research were to determine oil content of maize genotypes and its relationship with several agronomic traits. The oil content of maize genotypes ranged from 3.77 to 5.46%. Based on the correlation analysis, oil content correlated significantly with plant height, ear height, embryo weight, kernel weight, endosperm weight, and embryo and endosperm area ratio. In addition, oil content of maize genotypes could be estimated by a regression model involving embryo and endosperm area ratio, endosperm weight, ear height, cob lenght, number of kernel rows, number of kernel per row, cob diameter, and husk coverage (R2 = 79.66%; P = 0.0001). The oil-correlated traits and regression model obtained can be considered for facilitating selection for high oil maize genotypes. In addition, the results indicate that high oil maize can be bred and selected without affecting yield.Keywords: high oil maize, simultaneous selection, stepwise regression

Waterlogging is one of the most important constraints for maize production and productivity in many parts of the world, caused by flooding, continuous rainfall coupled with inadequate drainage or a high water table. The objective of this study was to determine the tolerance level of several hybrid maize genotypes to waterlogging stress. Screening of 27 hybrid maize genotypes was carried out in waterlogged condition and not waterlogged condition (as control) in a green house using a plastic cup of 300 ml volume in a randomized block design, 3 replications. Each genotype was planted in 5 seeds, grown by watering to V1-V2 phase which is characterized by the appearance of 1-2 complete leaves. Screening on waterlogged conditions performed on plastic-coated wooden tub. The water level during flooding is kept the same for 5 days. The results showed that the estimation of tolerance of hybrid maize genotypes to waterlogging using a flooding sensitivity index (FSI) which was calculated based on certain variables showed different FSI values for each variable. Determination of variables that have a large influence on the diversity of tolerance of maize genotypes to waterlogging can be known from the results of Principal Component Analysis. The results of the analysis show that the first principle component, the variable which has a big influence on the diversity of maize genotype tolerance to waterlogging stress is the number of roots with a proportion of diversity of 37.3%. The second principle component shows that the root length variable has a big influence with a proportion of variance of 22.52%. The cumulative proportion of the first and second major components is quite large at 59.83%. Based on the FSI root length variable, there are 3 hybrid maize genotypes that are tolerant of standing water while in the root number variable there are 13 tolerant genotypes with average fresh weight of shoot character, root number and stomata density higher than that in normal conditions.