Phenotypic and genetic relationships between yield components in maize

Summary Physiological components of kernel development — LAG period, effective filling period duration (EFPD) and grain filling rate (GFR) — ear moisture release (U), ear size (row number and kernels per row), days from emergence to silking and number of leaves, were examinated on 45 F₁ hybrids (10×10 diallel cross) in order to study their genetic relationships with yield. Combining ability analysis revealed that all trait variability derived mainly from g.c.a. effects. LAG period and EFPD were the traits most affected by genotype-environment interaction.Covariation analysis (path method) based on mean phenotypic values and on g.c.a. effects yielded similar information. It is shown that GFR and EFPD are both related to plant yield, but GFR made the most important contribution. On the contrary, a significant relationship between yield and LAG was not detected. Ear size components were also positively related to yield and had negative effects on GFR. These results indicate that, for our material, the dry matter accumulation rate is the main limiting factor of yield.Considering s.c.a. effects, kernel number per row made the most important contribution.     

Pollen Tube Growth Rates in Zea mays: Implications for Genetic Improvement of Crops

Speed of pollen tube growth is positively correlated with the quality of the resultant sporophytic generation. Therefore, gametophytic competition may be an important adaptive mechanism. Furthermore, pollen tube growth rates may be used to predict the quality of F(1) crosses in crop species.     

The Influence of Agglomeration Externalities on Manufacturing Growth Within Indonesian Locations

Differences in agglomeration externalities and industrial regimes between locations generate performance differentials for their localized economic activities. For more than two decades, scholars have debated which externality is dominant for growth and under which regime. This study aims to resolve this debate by analyzing the influence of agglomeration economies on the growth of five‐digit manufacturing sectors and firms for Indonesian cities and regencies between 2000 and 2009. This is investigated employing the recent reconceptualization of variety based on sectoral linkages distinguishing related and unrelated varieties, which allow assessing their idiosyncratic economic roles. The findings support that economic relatedness is the dominant source for expansion of sectors and firms within Indonesian locations. Specialized clusters and competition are inversely related to manufacturing growth, although the latter fosters sectoral employment within Indonesian regencies. Population density and human capital show antithetic effects between cities and regencies due to their distinctive urbanization trajectories and industrial compositions.