ABSTRACT In Colombia, the evidence of rootstock/scion incompatibility in avocado cv. Hass graft union has been increasing, generating concern among farmers. The objective was to evaluate the photosynthetic response of the avocado trees due to rootstock/scion compatibility in three locations. A split plots design with a blocking factor per locality was used. The main plot corresponded to the type of graft union (compatible and incompatible) and the subplots to leaf age during the 2020 and 2021 seasons. Climatic (water balance) and gas exchange variables (photosynthesis, transpiration, stomatal conductance, leaf temperature, and efficiency in instantaneous water use) were measured. The results indicate that the photosynthetic performance was not affected when the water balance was negative. Compatibility did not significantly affect gas exchange variables (A, gs, E, Tl, and WUEi) during the main and secondary harvest period. The leaf age/harvest period interaction shows that during the first months of leaf development, A, gs, E, and Tl are greater and are detrimental over time. It is concluded that the rootstock/scion compatibility does not significantly modify the capacity to assimilate CO2. At the same time, the variation in avocado photosynthetic activity depends on the age of the leaves and the harvest season.

ABSTRACT We hypothesized that common ragweed has rapid growth and development in shoots and roots, which explains its high potential for establishment in the areas, as well as the high regrowth capacity after cutting or application of contact herbicides. This study aims to evaluate the growth of the specie Ambrosia artemisiifolia. The treatments consisted of collection periods of common ragweed plants at fixed intervals of ten days, from 15 to 95 days after emergence (DAE), totaling nine evaluations. In each collection, the aerial part and the roots were evaluated. In the aerial part, stature, leaf area, number of leaves, and dry mass were evaluated. From these data, the absolute growth rate, relative growth rate, net assimilation rate and leaf weight ratio were calculated. The length, surface area, volume, average diameter, number of root tips, and dry mass were evaluated in the root. The common ragweed plants show rapid growth after emergence, with a similar response in aerial parts and roots. The potential for competition with crops is expressive. Furthermore, due to growth and development characteristics, the potential for regrowth is high and impacts the difficulties in controlling this species. Thus, the authors indicate that control should be carried out within a maximum of 25 days after emergence.

ABSTRACT The prediction of traits allows the breeder to guide strategies to select and accelerate the progress of genetic improvement. The objective of this work was to determine the best prediction approach and establish a network with better predictive power for white oat using methodologies based on artificial intelligence, and machine learning. Seventy-eight white oat genotypes were evaluated. The design was randomized blocks with three replications. The models were evaluated with and without fungicide, and prediction models were established using four sets of experiments. The grain yield was used as a response trait the others as explanatory traits. The coefficient of determination was considered to evaluate the proposed methodologies. The importance of the traits was assessed through the impact of destructuring or disturbing the information of a given input on the estimation of R2. For machine learning, decision trees, bagging, random forest, and boosting were used. The traits indicated to assist in decision-making are plant height, leaf rust severity, and lodging percentage. The R2 ranged from 30.14% - 96.45% and 10.57% - 94.61% for computational intelligence and machine learning, respectively. A high estimate of the coefficient of determination, which was larger than the other estimates, was obtained using the bagging technique.

ABSTRACT The knowledge about the genetic behavior of roots can be the solution to the main climatic problems and the key for increased production of agricultural crops. In inheritance studies, breeders usually conduct crosses between contrasting individuals to obtain a significant fraction of the genetic variance. To determine genetic parameters in beans from crosses within and between Middle American and Andean gene groups, 64 populations (breeders, F1 and F2) were evaluated under field conditions for the trait root distribution. Crosses between Middle American and Andean gene groups revealed significant estimates for genetic parameters (genetic variance, heritability, and average degree of dominance) compared to intra-pool crosses. However, only 4% of all hybrid combinations evaluated (F1 and F2) showed significant effects when compared to fixed populations (parents). Coupled with the insignificant number of progenies different from the parents, the differences detected revealed inferior performance, compared to the parents. The joining of alleles with identical provenance may be the main cause of the observed effects. The breeding strategy for root distribution should consider more divergent parents.

ABSTRACT The objective of this research was to identify the most effective method to estimate the repeatability coefficients in species of eucalyptus and to predict the minimum number of measurements necessary for growth traits. The experimental design was randomized blocks, with five species, with four repetitions. Data were collected from five measurements during the period from 2014 to 2016, evaluated according to the diameter, chest height and total height. The repeatability coefficient (r) was estimated using different strategies: analysis of variance (ANOVA), principal component analysis based on the correlation matrix (PCCOR), principal components based on the phenotypic variance and covariance matrix (PCCOV), and structural analysis based on the correlation matrix (SACOR). The PCCOR and PCCOV provide accurate estimates of the repeatability coefficient and the number of measurements required. At least five measurements are necessary to predict the real value, with a minimum accuracy of 80%.

ABSTRACT Hail netting increases natural fruitlet drop. Mixing lower concentrations of Plant Growth Regulators (PGRs) and spraying on more advanced fruitlets could promote adequate crop load management and improve fruit quality. The objective of this study was to evaluate thinning programs with low concentrations of PGRs sprayed at advanced fruitlet size looking for reducing crop load, enhancing fruit quality, and preserving yield. On 2020/21 and 2021/22, in an orchard covered with hail netting in Bom Jesus-RS, eight programs were tested on vigorous ‘Maxi Gala’: Benzyladenine (BA)+Gibberellic acid4+7 (BA-GA) at full bloom (FB) and BA+Ethephon (ETH) at 15mm; BA-GA at FB and Naphthalene acetic acid+Carbaryl (CB) at 7 mm; BA-GA at FB and BA+CB at 15 mm; ETH+CB at 15 mm and Metamitron (MM)+ETH at 20 mm; BA-GA at FB and BA at 7 mm and MM at 20 mm; MM at 7 mm and MM at 20 mm; Manual Thinning Only; Untreated Control. The treatments containing CB reduced fruit set, although diminished yield unsustainably. All PGR programs improved fruit quality. In conclusion, BA-GA at FB and BA+ETH at 15 mm, and MM at 7 mm and MM at 20 mm reduce crop load, preserve yield and improve fruit quality.

ABSTRACT The factors and their levels influencing the seed germination process are well-known for most traditional forest species. But, for Jacaranda micrantha, a native and aesthetically appealing species, some factors influencing the germination process are not well described. So, we evaluated the effect of different light conditions and soaking on the germination of seeds. Four light intensity treatments (5, 25, 50, and 100%) and four soaking times were tested (0, 12, 24 and 48 hours). In both procedures, a completely randomized design was applied, with four treatments of four replicates containing 25 seeds each. Daily evaluations were performed to determine the germination percentage and the germination speed index (IVG). Seeds of J. micrantha presented a better germinative potential in lower light intensities, but more abnormal seedlings were observed at very low-intensity light (5%). The imbibition of seeds was efficient in accelerating the germination process, and the 12-hour soaking time in the water was the most efficient, contrary to what is described in the literature.

ABSTRACT Worldwide, a comprehensive characterization has been implemented in different farming systems but not in sugarcane agroecosystems for panela production in high Andean regions. In Colombia, panela is an important staple food, being the second largest producer in the world; however, the predominant cropping systems in different regions have not yet been fully described. Using secondary information, as well as the implementation of semi-structured surveys with farmer participation, together with geographic information system analysis tools, 341 farms and management measures were identified in a large sugarcane productive region in Colombia. Sufficient soil and climatic conditions were found for production, siltstone parent material (38.84%), predominant spine relief (83.23%), rainfall (1,000 mm), relative humidity (86%) and annual temperature (23 °C). The types cropping systems were determined, characterizing their management, as well as variables of the socioeconomic structure of the region. The production systems were classified into five gropus, were the typification of farms was mainly by three cutting systems called “parejo”, “entresaque” and a new cutting system was identified, called “parejo” without renewal. As a complement, deficiencies were found in socioeconomic, technical and technological aspects in the province of Gualivá (Cundinamarca), being a generalized panorama in this important productive system in the country.

ABSTRACT The combination of management practices affects weed populations and biodiversity. The objective was to evaluate the infesting weed community in the implementation of a corn silage (Zea mays L.) /pearl millet (Pennisetum glaucum L)/corn silage succession system subjected to early potassium fertilization in the winter crop. The experiment began in October 2019 under fallow area. In the 2019/20 summer season, corn silage was grown in a complete area. In the 2020 fall/winter season, the plots consisted of pearl millet, six doses of potassium fertilization (0, 30, 60, 90, 120 and 150 kg ha-1) and one fallow. In the 2020/21 summer season, the treatments consisted of corn silage and six doses of K2O, complementing the treatment applied in the previous harvest (120, 90, 60, 30, 0 kg ha-1) and one with recommended fertilization. Phytosociological evaluations of weeds were performed using a 0.25 m2 square. The density and number of species increased in the first year. Early fertilization at doses of 90, 120 and 150 kg ha-1 of K2O increased the dry weight of weeds before planting and at V4 stage of the corn silage cultivated in sequence; however, were lower than those for plots fallowed in the winter.

ABSTRACT The aim of the study was to characterize the bioactive compounds present in sugarcane syrup, analyze the color, to evaluate the antioxidant activity as well as the stability of the bioactive compounds during a 60-day storage under freezing conditions. The experiment was conducted with five sugarcane varieties grown in Canguçu-RS. The content of carotenoids, total phenolic compounds, flavonoids, vitamin C and chlorophylls was determined, and also the antioxidant activity and color were also evaluated. The content of carotenoids (1.82-6.67µg.g), total phenolic compounds (191.06-226.54 mg EAG.L-1), flavonoids (70.73-189.57mg EQ.g-1), vitamin C (0.10-0.35 mg ascorbic acid .100g-1), total chlorophylls (36.13-37.67 g.kg-1), and percentage of antioxidant activity (50.92-68.76%) varied by cultivar. The content of chlorophyll b was higher than the content of chlorophyll a in all cultivars. The color analysis showed that the samples had a strong tendency to green and yellow color. The content of carotenoids increased during 60 days of storage, while the content of phenolic compounds and chlorophylls decreased. The percentage of antioxidant activity decreased after 30 days of storage. It can be concluded that the sugarcane grown in Canguçu-RS had a high content of bioactive compounds, adequate color and high antioxidant activity when compared to the literature.