ABSTRACT Small grain cereals in lower latitude areas usually mature under terminal drought conditions that affect their agronomic performance. An experiment was conducted to compare agronomic traits, grain yield, and protein content under control and terminal drought conditions of 15 two-row and 10 six-row barley (Hordeum vulgare L.) genotypes. The experiment was set up at two locations for two growing seasons (2011, 2012) and two treatments. One treatment was terminal drought (D) simulated by the mechanical removal of all leaf blades 7 d after the heading of each genotype, and a control (C) treatment in which plants were left intact. On average, defoliation caused a greater reduction in grain yield and protein content of the six-row genotypes (37.6% and 12.3%, respectively) than the two-row genotypes (28.8% and 7.1%, respectively). On the other hand, test weight of six-row genotypes showed better tolerance to terminal drought. According to the multivariate function analysis, the genotypes of both types of barley with a high test weight, a longer uppermost internode, and a longer grain filling period had high protein content under terminal drought stress. In contrast to six-row genotypes, it is possible to breed two-row genotypes that not only have high grain yield but also high protein content under both optimal and drought stress conditions.

Association analysis is a relatively novel approach in quantitative traits studies that allows high resolution mapping and time efficient and direct application on breeding material. Since the markers, which are close to the quantitative trait loci stable across environments and genetic backgrounds, may be valuable for marker assisted selection, we chose microsatellite markers previously linked to traits of interest in various mapping studies. A set of 36 microsatellite markers positioned near important maize (Zea mays L.) agronomic loci was used to evaluate genetic diversity and determine population structure. To verify the associations between the markers and traits, a panel of diverse maize inbred lines was genotyped with microsatellites and phenotyped for flowering time, yield and yield components. A relatively high level of polymorphism detected in number of alleles per locus (8.2), average polymorphic information content value (0.64), and average gene diversity (0.684) lines showed the analyzed panel of maize inbred contained significant genetic diversity and was suitable for association mapping. The population structure estimated by model-based clustering method grouped maize inbred lines into three clusters. The association analysis using the general linear and mixed linear models determined significant correlations between several agronomic traits and three microsatellites on chromosomes 3, 5, and 8, namely umc1025, bnlg1237, and bnlg162 consistent across the environments, explaining from 4.7% to 18.2% of total phenotypic variations. The results suggest that the chromosome regions containing quantitative trait loci (QTLs) associated with multiple yield-related traits consistently across environments are potentially important targets for selection.

Plus-hybrid effect refere to a combined effect of cytoplasmic male sterility (CMS) and xenia in maize (Zea mays L.) It could be used in commercial production by growing a mixture of 80% CMS hybrid and 20% of another fertile hybrid. The aim of this research was to examine individual and combined CMS and xenia effects on two hybrids widely grown in Serbia. Sterile and fertile versions of ZP 1 and ZP 2 hybrids (three-way; Iodent x Lancaster dents) were used as females, while ZP 1, ZP 2, ZP 3, ZP 4, and ZP 5 (three-way or single cross; Iodent (BSSS) x Lancaster dents) were used as pollinators. All of them belong to medium maturity group. The trial was set up at one location in Serbia (Zemun Polje) in 2009, 2010, and 2011. Molecular analysis of the five genotypes was done using simple sequence repeat (SSR) primers. Plus-hybrid effect on grain yield ranged from -6.2% to 6.2%; on thousand kernel weight from -1.7% to 5.2%; on number of kernels per area from -1.0% to 8.0%. The poor response could be due to a use of three-way instead of single cross hybrids in S type of sterility. Modified Rogers’ distance between hybrids was in the range 0.211 to 0.378 and was not relevant for the effect, which depended mostly on the sterile hybrid genotype and the fertile hybrid pollinator ability. This approach should be more suitable for female hybrids with slightly poorer performance, already being produced on a sterile base.

Foram selecionadas sete características relacionadas ao florescimento e expressão do sexo no melão e, em seguida, observada a reação de dois reguladores de crescimento (Ethrel e ácido giberélico). Quatro genótipos de flores monóicas (Gergelim, ED-3, ED-4, Pobeditel) e quatro genótipos andromonóicos (Melão chinês, Anannas, Fiata, A2-3lb) foram ensaiados durante dois anos. Ethrel teve um efeito mais forte do que o ácido giberélico, aumentando o número de flores femininas/hermafrofitas por planta para 7,18 (40,61%) e reduzindo o número de flores masculinas para 21,47 (17,98%). Ethrel adiantou o aparecimento da primeira flor feminina/hermafrofita em 3,68 dias, e atrasou o aparecimento da primeira flor masculina em 16.07 dias. Como consequência, percebe-se que Ethrel prolonga o período entre o aparecimento da primeira flor fêmea/hermafrodita até a primeira flor masculina de 0,1 dia para 21,57 dias, sendo este o efeito mais forte (99,49%).

Seven traits related to flowering and sex expression in melon were studied and their reaction to application of two growth regulators (ethrel and gibberellic acid) was observed. Four monoecious genotypes (Sesame, ED-3, ED-4, Pobeditel) and four andromonoecious genotypes (Chinese muskmelon, Anannas, Fiata, A2-3lb) had been used for experiments. According to the results, ethrel had higher effects on the investigated traits than gibberellic acid. Ethrel increased the number of perfect flowers per plant for 7.18 (31.42%), reduced the number of male flowers per plant for 21.47 (17.98%), affected earlier appearance of the first pistillate/perfect flower for 3.68 days, and delayed the appearance of the first staminate flower for 16.07 days. Changes in the last two traits caused an extension of the period from the emergence of the first pistillate/perfect to the first staminate flower from 0.1 to 21.57 days, which represents the strongest effect of ethrel. Gibberellic acid had generally opposite effects on the studied traits.