Chickpea production in the short growing season of the Canadian Prairies is still a challenging task due to excessive and continuous vegetative growth which often results in severe yield and quality reduction. This study examined the effects of three plant growth retardants (PGR), Chlormequat Chloride (CCC), Prohexadione Calcium and Trinexapac Ethyl applied during flowering stage on vegetative growth, seed quality, yield and crop maturity of the Kabuli chickpea cultivar CDC Frontier. Field experiments were conducted at Brooks and Bow Island in southern Alberta in the 2010 and 2011 growing seasons. Four concentrations of each PGR were applied at 10, 20 and 30 days after flowering (DAF) stages. During the 2010 growing season the crop experienced above average moist and cooler temperature conditions. In contrast, later half of the 2011 growing season was above average dry and hot. None of the three PGR tested in this study had a significant effect on plant height at 30 days after treatments or on above ground biomass plant-1 at harvest. Application of PGR had no significant effects on the number of seeds m-2, except at the Brooks rain-fed site in 2011 where the PGR treatment applied at 10 and 20 DAF increased the number of seeds m-2 at harvest. An increase of 1000-seed weight of marketable seeds was obtained with Prohexadione Calcium and Trinexapac Ethyl applications at Bow Island, but the effects were not consistent across sites and years. Results suggested that the effect of PGR on 1000-seed weight of marketable seeds mainly depended upon the growing environment and the type of PGR. In general, PGR applications reduced the total and marketable seed yields. Application of Prohexadione Calcium and Trinexapac Ethyl at the Bow Island site delayed crop maturity in 2011. In contrast, the application of CCC at 6000 mg L-1 at 20 DAF accelerated crop maturity at the Brooks irrigated site in 2011. In addition to this main study, the potential effects of Pyraclostrobin and Prothioconazole fungicides on the activities of the three PGR were compared by a separate experiment conducted at the Brooks irrigated site in 2011. The results of that study revealed that there were no significant differences in the effects of PGR on chickpea vegetative growth, seed yield parameters and maturity when they were applied as a mixture with either Pyraclostrobin or Prothioconazole fungicide. In summary, results revealed that PGR applied during flowering stage were not effective on controlling vegetative growth of chickpea and did not improve seed yield and crop maturity. Their effects on yield-related traits were highly inconsistent. Thus, it can be concluded that the application of PGR is not a reliable agronomic option to handle the production issues associated with continues vegetative growth at the late reproductive stage of the chickpea cultivar CDC Frontier under the western Canadian growing conditions.

Deux populations de tortues d’Hermann (Testudo hermanni, une espèce à maturité tardive ~10 ans) ont été étudiées sur le continent et sur une île dans la région du lac Prespa en Macédoine. Avant la maturité, la croissance des tortues est lente, puis accélère, entrainant une augmentation des taux de survie annuelle (de 0.30 à 0.70) et des variations de taille. Un potentiel pour une croissance continue, le durcissement de la carapace et un plateau de survie à cinq ans (0.90) induisent de fortes variations interindividuelles des trajectoires de croissance, et donnent une gamme étendue des tailles asymptotiques. Nos données questionnent la notion d’une taille unique à maturité puisqu‘une augmentation progressive des taux de testostérone suggère que la maturité s’établit pour des tailles entre 115 et 140 mm. Dans le genre Testudo les femelles sont plus grandes que les mâles ; les estimations des tailles asymptotiques observées le confirment. Mais sur l’île les plus grandes tortues sont des mâles. Avec ~100 individus/ha et un sexe ratio opérationnel (OSR ♂/♀) de ~11, la coercition exercée par les mâles entraine des blessures cloacales chez les femelles et dégrade leur condition corporelle, augmentant les coûts des accouplements. La survie des mâles (0.97) surpasse celle des femelles (0.84). Les femelles insulaires ne vivent pas longtemps, sont détournées de la reproduction et le faible recrutement biaise encore le sexe ratio, poussant la population vers l’extinction. Les rares femelles souffrent tandis que les mâles frustrés exhibent des comportements homosexuels fréquents, voire exubérants. Ces résultats sont discutés dans un contexte de conservation. / Two populations, island and mainland, of promiscuous sexually coercive Hermann tortoises (Testudo hermanni, a species with delayed maturity ~10 years) from the Prespa Region in Macedonia were scrutinized. Prior maturity, tortoises first grow slowly, thereafter gradually increase growth speed, variation in body size and survival probability (mean annual survival rate: 0.30 to 0.70). Potential for indeterminate growth, progressive hardening of the carapace and a survival plateau at the age of five (0.90) promote inter-individual variations in growth trajectories and a wide range of adult asymptotic sizes. Our data question the classical notion of a given size at maturity; instead progressive raise of testosterone levels suggests that maturity is established in growing males ranging from 115 to 140mm in body length. In the Testudo genus females are larger than males; asymptotic estimates of body size show that the studied populations make no exception. Yet, the largest island tortoises are males. With ~100 individuals/ha and an operational sex ratio (OSR ♂/♀) of ~11, male sexual coercion provokes cloacal injuries to females and reduces their body-condition, increasing female mating costs. Male adult survival (0.97) is greater compared to female survival (0.84). Island females do not live long, are discouraged from reproduction and low recruitment further exacerbates OSR-bias, eventually leading to population extinction. Where females suffer and are underrepresented, frustrated males exhibit frequent same-sex sexual behaviours along with extravagant sexual behaviours. The results are discussed in a conservation framework.

The sexual size dimorphism (SSD) is widespread among animals but proximate mechanisms of its ontogeny are still poorly understood even in important groups of vertebrates such as reptiles. Previous experiments in geckos showed that growth of both sexes slows substantially at their older age. Their SSD develops considerably a long time after sexual maturity, it is associated with earlier growth deceleration in the smaller sex and it is controlled by ovarian rather than testicular steroids. The aim of the thesis was to explore the previous knowledge by studying the ontogenesis of the sexually-dimorphic bone growth of the gecko Paroedura picta, the male- larger species with the most explored proximate mechanisms of SSD among geckos. I was most interested in the ontogeny of the growth plates activity and the epiphyseal ossification of the femur in both sexes and their relationship to age, body length, gonadal activity and levels of sex-specific steroids (estradiol and testosterone). The results show that P. picta has determinate growth and that epiphyseal ossification does not contribute to the SSD. The femoral growth plates close at the same age in both sexes; however, their closure occurs at smaller body length in females than in males. In the context of this and the previous studies, estradiol or other...