Asparagus is especially suitable for polyploidy breeding. The aim is to develop clone-based hybrid varieties, in particular male 4x varieties. For this purpose, genetically divergent diploid idiotypes") are subjected to mitotic or meiotic polyploidization. In developing hybrid partners, special attention is paid to resistance in addition to yield and quality characters. Early diagnoses are apphed in selection so as to shorten breeding times. Somaclonal variations may occur relatively often on in vitro propagation; these need to be eliminated. Triplex and quadruplex type males are suitable for paternal hybrid partners. Strong inbreeding depressions need to be avoided in their production.

Breeding for higher grain yield in maize (Zea mays L.) using increased selection densities has produced varieties that are adapted to grow at higher population densities. While the effects of density on final grain yield and plant phenotypes are well known, how density affects the early‐season growth of the plant has been less studied. The objective of this experiment was to examine the effects of high planting density on the growth of stalk, tassel, and ear shoots in unselected Iowa Stiff Stalk Synthetic (BSSS) and Iowa Synthetic Corn Borer No. 1 (BSCB1) and in populations that have been selected for high grain yield via a reciprocal recurrent selection program. The selected and unselected populations were planted at four densities ranging from 3.23 to 12.92 plant m−2 in six environments near Ames, IA, over 3 yr. Increased planting density affected plant organ growth timing differently in BSSS and BSCB1. High‐density delayed stalk biomass accumulation in BSCB1 but not BSSS and delayed ear shoot and tassel biomass accumulation in BSSS but not BSCB1. Differences in biomass accumulation and partitioning between unselected populations were generally not observed between selected populations, suggesting that selection caused a convergence in growth patterns between the populations. Increased density lowered maximum growth rates for all plant organs, but reduction in growth rate as a result of density occurred at higher density in selected populations than unselected populations.

Seeds of sweet cherry (Prunus avium) possess a strong endodormancy response that traditionally requires months of stratification before germination can occur. Accelerating artificial dormancy release could be an important aspect of improving progress in a sweet cherry breeding program by increasing the first season growth period. In this study, seeds were exogenously treated with ethephon, 1-aminocyclopropane-1-carboxylic acid (ACC), kinetin, hydrogen peroxide, and acidified nitrite to attempt to induce germination with reduced stratification times. Findings showed that ethephon, ACC, and hydrogen peroxide all significantly increase early seed germination rates. Stratification time had the largest effect on increasing germinations, with significantly higher germination percentages accompanying increased stratification times that plateaued at 3 months of stratification. Stratification is vital for proper seedling development because plants grown from seeds with no stratification are significantly shorter and have reduced internode lengths compared with seeds with 4 weeks of stratification.

Recurrent selection………………………………………………………………...5 Reciprocal recurrent selection……………………………………………………..5 BSSS………………………………………………………………………………6 BSCB1………………………………………………………………………….....6 BSSS(R)C17 and BSCB1(R)C17…………………………………………………6 Genetic gain in the BSSS/BSCB1 program……………………………………….6 Inbreeding in the populations……………………………………………………...8 Heterosis in the population crosses………………………………………………..9 Changes associated with selection for yield in the BSSS and BSCB1 populations.