Association Mapping of Physiological and Morphological Traits Related to Crop Development under Contrasting Nitrogen Inputs in a Diverse Set of Potato Cultivars

Ample nitrogen (N) is required for potato production, but its use efficiency is low. N supply strongly interacts with maturity type of the cultivar grown. We assessed whether variation among 189 cultivars grown with 75 or 185 kg available N/ha in 2 years would allow detecting quantitative trait loci (QTLs) for relevant traits. Using phenotypic data, we estimated various traits and carried out a genome-wide association study (GWAS) with kinship correction. Twenty-four traits and 10,747 markers based on single-nucleotide polymorphisms from a 20K Infinium array for 169 cultivars were combined in the analysis. N level affected most traits and their interrelations and influenced the detection of marker–trait associations; some were N-dependent, others were detected at both N levels. Ninety percent of the latter accumulated on a hotspot on Chromosome 5. Chromosomes 2 and 4 also contained regions with multiple associations. After correcting for maturity, the number of QTLs detected was much lower, especially of those common to both N levels; however, interestingly, the region on Chromosome 2 accumulated several QTLs. There is scope for marker-assisted selection for maturity, with the main purpose of improving characteristics within a narrow range of maturity types, in order to break the strong links between maturity type and traits like N use efficiency.

Evaluating Sustainable Intensification of Groundnut Production in Northern Ghana Using the Sustainable Intensification Assessment Framework Approach

The sustainable intensification of crop production system requires the efficient use of resources. A 3-year on-farm experiment was conducted to determine the sustainability of plant density for groundnut production in Northern Ghana using the sustainable intensification assessment framework (SIAF). The SIAF allows the assessment of the sustainable intensification potential of the agricultural system in five domains: productivity, economics, environment, human, and social. The experiment was laid out in a strip plot design with six groundnut varieties (early maturity type: Chinese, Yenyewoso, and Samnut 23, and late maturity type: Azivivi, Mani pinta, and Samnut 22) as the horizontal plot factor and four plant densities (22, 15, 11, and 9 plant/m2) as the vertical plot factor. Using the SIAF as a guide, data on grain and fodder yield (productivity), net income and benefit cost ratio (economic), vegetative cover at 30, 40, and 50 days after planting and harvesting and biological nitrogen fixation (environment), calorie and protein production (human), and technology rating by gender (social) were recorded to calculate the sustainability indices of the treatments. The results showed that the sustainability indices for the Yenyewoso and Mani pinta groundnut varieties were above 1 in all the regions, indicating that both groundnut maturity types are sustainable for cultivation in the Northern regions of Ghana. Planting both groundnut maturity types at a density of 22 plant/m2 increased the sustainability index threefold compared with the farmer practice (9 plant/m2) and 79% compared with the 11 and 15 plant/m2. This suggests that planting groundnut at a density of 22 plant/m2 will sustainably intensify groundnut production in Northern Ghana and similar agro-ecologies across West Africa.

The Effect of Plant Densities and Different Maturity Types on Maize Grain and Fodder Yield

Three maturity types of maize, Abontem (extra early maturing), Omankwa (early maturing) and Obaatanpa (medium maturing) were evaluated at three different plant densities 66,667 plants ha-1, 100,001 plants ha-1 and 133,334 plants ha-1 to determine the optimum plant density for grain and fodder yield. The experiment was laid in randomized complete block with four replicates factorial fashion. The maize maturity type had significant influence on all the traits measured. Plant density had significant effect on cob width, grain and fodder yield but no significant influence on plant height, days to 50% anthesis and silking, anthesis and silking interval, cob length and 1000 grain weight. Obaatanpa (medium maturing) was the maize maturity type that produced the highest grain yield (3139 kg ha-1) and fodder yield of (4173 kg ha-1). Obaatanpa with 133,334 plants ha-1 interaction produced the highest grain and fodder yield with 3186 kg ha-1 and 4240 kg ha-1 respectively. Obaatanpa with 133,334 plants ha-1 would be recommended for commercial grain and fodder production because the high yielding potential as observed in the study.

DETERMINANT TRUE DISCOUNT PADA PENAWARAN SAHAM PERDANA PERIODE 2010-2014

This study aims to obtain empirical evidence regarding DETERMINANT TRUE DISCOUNT IN PRESIDENT STOCK OFFERS 2010-2014. Diamana, Underpricing is proxied by True discount as the dependent variable and the Underwriter Reputation, Company Size, Company Age, Type of Company or Industry Sector, and Share Percentage offered as independent variables. The population in this study are all companies that made an initial public offering on the Indonesia Stock Exchange in 2010 to 2014 as many as 126 companies. The sample of this research were 80 companies taken from the population using purposive sampling method, besides that the researchers used secondary data type data. The results of this study indicate that the variable Company Size, Company Type or Industrial Sector, and the percentage of shares offered affect the True Discount given to investors in companies that register (register) on the Indonesia Stock Exchange in 2010-2014. While the Underwriter Reputation and Company Age variables do not affect the True Discount given to investors in companies that register (register) on the Indonesia Stock Exchange in 2010-2014. Then Reputation Underwriter (RU), Company Size (size), Age of Company (Maturity), Type of Company (JP), Percentage of Shares offered (PS) jointly affect the True Discount given to investors in companies that register (listing ) on the Indonesia Stock Exchange in 2010-2014.

Evaluation of the Length of the Vegetation Period of the Potato

Potato cultivars are classified into maturity groups according to the length of the vegetation period required to produce a harvestable product. Although accurate classification of potato cultivars to a specific maturity group is of great practical importance, there is no standard method to characterize the maturity type of potato cultivars. In this work, the method of evaluation of vegetation period routinely used at IHAR-PIB, Młochów Research Center is described.