Hybrids In Locations Research Articles

Introgressive hybridization in two Indo-West Pacific Rhizophora mangrove species, R. mucronata and R. stylosa

Natural hybridization is common in plants, including mangroves. Three Rhizophora mangrove species are recognized in the Indo-West Pacific region, namely R. apiculata, R. mucronata, and R. stylosa. So far, R. apiculata has been known to form sterile hybrid offspring with R. mucronata (= R. x annamalayana) and with R. stylosa (= R. x lamarckii). A third hybrid between morphologically similar R. mucronata and R. stylosa was only recently shown to exist, via DNA sequencing. However, it has been suspected that this newly discovered hybrid may be fertile, with potential to interbreed to give rise to advanced-generation hybrids in locations where both parental species occur. In this study, inter-simple sequence repeat (ISSR) markers were used to survey several stands where R. mucronata and R. stylosa co-occur. By screening through 26 ISSR primers, a set of species-specific diagnostic bands for each species were first identified from standard samples before being used to genotype the test samples. A chloroplast DNA locus was also sequenced in the test samples to determine the direction of hybridization. Results showed that hybridization occurred between R. mucronata and R. stylosa in all investigated locations with differing levels of introgression, and that it could happen in any direction.

G x E Interaction on Yield Stability of Five Sweet Corn Hybrids Grown under Different Agricultural Systems

Yield stability in sweet corn and its dependence on G x E interaction were investigated in a series of two way experiments. Five Romanian sweet corn hybrids were tested in three years (2008-2010) in three locations of Central Transylvania in different soils and climatic conditions. The experiments were organized in a split plot design in which, on a general level of organic fertilization (40 t/ha manure), four levels of mineral N fertilization were applied (kg/ha, active matter): N0, typical for organic technologies; N50, corresponding to the low-input (sustainable) system; N100 and N150 customary with conventional system of agriculture. Based on ear yield data registered for hybrids in locations x years x cropping system, a phenotypic index (Pi) was computed for each sweet corn hybrid illustrating the stability of their cob yields, with and without husks. The share of genotypic and G x E effects in the total value of Pi have been estimated. In different agricultural systems the tested hybrids were classified differently based on their Pi values. It is concluded that, at least for the time being, the initiation of an organic breeding program for sweet corn, in Romania, is not economically justified since all semiearly and semilate tested hybrids yielded satisfactorily under organic agricultural practices. Moreover, among the recently released sweet corn hybrids one can find certain genotypes highly suitable to organic (i.e. ‘Deliciul verii’, ‘Estival’) or low input (‘Dulcin’, ‘Estival’) agricultural practices. These three hybrids recorded the highes ear yields (with and without husks) over years, locations and agricultural systems.

Power quality impact of a sea located hybrid wind park

The power quality impact of a 2.5 MW wind park has been measured and analyzed. The turbines in the park operate at variable speed at low wind speeds and at fixed speed at higher wind speeds. The harmonic current injection is low and the calculated flicker contribution is seldom above 0.25. The wind park also has the potential to maintain the voltage on the supplying grid below a certain limit, in this case 11 kV.