ABSTRACT Germination tests are carried out for a wide variety of purposes in weed control. The variability in seed germination counts raises the overdispersion problem. The objective of this study is to compare different approaches used in solving overdispersion and to offer practical solutions to researchers. The data sets were created from seed germination counts, which examined the allelopathic effect of white cabbage (Brassica oleracea L. var. capitata L.) on the germination of some culture and weed seeds. Methanol and aqueous concentrations (30%, 40%, 50%) of dry and fresh white cabbage were used. Assuming the Poisson distribution in the generalized linear mixed model, overdispersion problem was determined in redroot pigweed (Amaranthus retroflexus L.), lamb’s quarters (Chenopodium album L.) and sugar beet (Beta vulgaris L.) Equidispersion was determined in corn (Zea mays L.) and it was perfectly adapted to the Poisson distribution. In order to overcome the overdispersion problem, generalized Poisson distribution outperformed negative binomial distribution. The increase concentration in the generalized Poisson in weeds, fresh cabbage methanol and aqueous applications were very effective reducing germination (p < 0.05). The best results in weed seeds were obtained at 50%. Unlike weeds, 30% concentration of dry cabbage methanol and aqueous were considered as the upper limit in order not to adversely affect germination in Z. mays and B. vulgaris. Consequently, in germination tests, the problem of overdispersion is inevitable as a result of excessive variability. For germination count data, generalized Poisson distribution is viable option and powerful alternative to accurately describe mean-variance relationship.

ABSTRACT The objective of this study was to determine the sexual parameters in young bucks with different sexual activity and the effect of experience (age) on sexual parameters in bucks. Fifteen young, sexually inexperienced (SI) and five adult, sexually experienced (SE) Saanen × Hair goat crossbred bucks were used in this study. Bucks were individually exposed to three estrus does for 15-min periods during four sexual performance tests, which were carried out every other day to determine some sexual behavior traits such as flehmen response, reaction time, and ejaculation efficiency. Sexually inexperienced young bucks were evaluated based on their sexual activity (active (AC) vs inactive (IA)) and presence of horn. It was found that AC bucks had significantly higher serum testosterone concentrations (31.5 vs 21.5 ng/mL) and weight loss (114.2 vs 51.2 g/day) than IA bucks. In addition, weight loss was significantly correlated with ejaculation efficiency in young bucks. On the other hand, horned bucks tended to have higher ejaculation efficiency with significantly longer reaction time than polled bucks. For experience (age) classes, SE bucks had higher testosterone concentration (76.0 vs 31.5 ng/mL) and weight loss (16.7 vs 8.6%) than SI active young bucks. However, the effect of experience on other sexual performance traits was found to be limited. Overall, these results indicate that testosterone concentration may affect sexual performance of young bucks in the mating season. Age-related sexual experience is not a determining factor for sexual performance in bucks. However, sexual performance data alone may not reflect reproductive outcomes without semen data.