ABSTRACT.- Flower induction and differentiation are complex phenomenon not fully understood in pear trees. Paclobutrazol (Pbz), Ethephon (Eth), and naphthaleneacetic acid (NAA) exogenous applications could be potential tools to increase return bloom and yield, and to manage the alternate bearing in some pear cultivars. The objective of this research was to evaluate the effect of Eth, Pbz, and NAA on return bloom and yield of 'Rocha' pear trees in different climatic conditions of Southern Brazil.

ABSTRACT.- Fruit set of some apple cultivars is low despite abundant flowering. This could be, among other things, due to ethylene production of the flowers and or short ovule longevity. 'Minneiska' apple has been notable for its low productivity if not managed adequately. To better understand the cause of the low fruit set presented by this cultivar, a series of trials evaluating ethylene evolution and fruit set were conducted from 2017 to 2019. Flowers/fruitlets of different apple cultivars showed a distinct pattern in ethylene evolution.

ABSTRACT. - Understanding the transition from quiescent primordial follicles to activated primary follicles is vital for characterizing ovarian folliculogenesis and improving assisted reproductive techniques. To date, no study has investigated preantral follicle crowding in the ovaries of livestock or characterized these crowds according to follicular morphology and ovarian location (portions and regions) in any species.

ABSTRACT.- 'GVU Yvyrá' is a new apple cultivar developed and released by "Grupo Viveros del Uruguay". Trees are rustic, vigorous, with good branch growth behavior, and presenting a low chill requirement. It presents early flowering, starting around September 1st, and its harvest begins before January 15th (in southern Uruguay). Large to very large fruits, with cone shape, approximately 90% red-brown blush and sweet, yellow colored flesh, and a good cold storage potential.

ABSTRACT.- Three major ontogenetic processes are distinguished in pome trees:flower induction, initiation, and differentiation and after that anthesis. Flower initiation is an irreversible process marked by histological changes and intensive mitotic activity. The formation of an apical dome is the first visible signal of floral initiation.

ABSTRACT.- After having been brought to America 400 years ago, the Criollo horse reproduced freely for centuries in the southern part of the American continent. Roughness, resistance, and endurance are typical characteristics of this breed of horses. Although the natural selection that occurred over the centuries may have positively influenced the fertility and longevity of this breed, information regarding ovarian function and other reproductive aspects of Criollo breed mares under natural or controlled management conditions is scarce.

ABSTRACT.- The effects of gestation loss (PDG) on the reproductive cycle of dairy cows is an issue of great importance for dairy herds, since it is the main factor that generates suboptimal reproductive efficiency, leading to a negative impact on profitability. (Diskin et al., 2016). In addition, the PDG is considered a key indicator of the health and welfare situation in dairy herds (Campero et al., 2017). PDGs are multifactorial in nature with environmental, nutritional, metabolic, hormonal, genetic and/or health origins (Wiltbank et al., 2016).

ABSTRACT.- In order to assess the effect of equine chorionic gonadotropin (eCG) administered on Day 5 or 7 of a fixed-time artificial insemination protocol (FTAI) in anestrous suckled beef cows, two experiments were performed to determine the following endpoints:Experiment 1 (n = 22), preovulatory follicle (POF) diameter, ovulation time, corpus luteum (CL) area, estradiol (E2) and progesterone (P4) concentrations; and Experiment 2 (n = 676), a field trial to evaluate conception rate using the same experimental design.

RESUMEN. Eragrostis plana (capín Annoni) es una importante gramínea invasora de los pastizales del Río de la Plata, frecuentemente asociada a sitios con alto grado de estrés abiótico (e.g., estrés hídrico). Por medio de dos experimentos complementarios, evaluamos el efecto relativo del estrés hídrico en el desempeño y la habilidad competitiva de E. plana y de dos gramíneas nativas:Eragrostis bahiensis y Sporobolus indicus. En el primer experimento estudiamos el desempeño de las especies en dos tratamientos (n=5), con y sin estrés hídrico.

ABSTRACT.- Yield and fruit quality are two of the most important parameters for the profitability of vegetable crops. In commercial vegetable production, nitrogen (N) is commonly applied in excess, which is associated with nitrate (NO3−) leaching loss. In addition, excess N application may affect yield and fruit quality.