Carlos Eduardo Lazarini da Fonseca

Aim of study: This study aimed to estimate and compare the accuracy of tree height and timber volume of four Cerrado forest tree species using a digital canopy height model (CHM) derived from unmanned aerial vehicles (UAV)-based photogrammetric data and field height measurements. Area of study: The research was conducted on a rural property undergoing productive recovery with native tree species, located in the Central Plateau of the Cerrado biome, Brazil. Material and methods: A UAV equipped with a multispectral camera was used to acquire a digital CHM of the study area. This data was then compared to field measurements of diameter at breast height (DBH) and total height of 143 individual trees from four species: Anadenanthera colubrina (Vell.) Brenan, Astronium urundeuva (M. Allemão) Engl., Astronium fraxinifolium Schott., and Plathymenia reticulata Benth. Main results: The tree heights obtained from the UAV-based multispectral camera were statistically similar to those measured manually using a graduated ruler, showing a Pearson correlation coefficient of 0.81 and a root mean squared error (RMSE) of 1.22. The volume estimates showed an even higher correlation of 0.97 and an RMSE of 0.01. Research highlights: UAV-based photogrammetric data provides a fast and accurate method for estimating the height and volume of native Cerrado tree species, demonstrating its significant potential for application in forest inventories and management practices.

O objetivo do estudo foi aumentar a eficiência da seleção fenotípica de genótipos promissores para a produção de frutos e pirênios de pequizeiro (Caryocar brasiliense Cambess.), considerando informações em diferentes safras. Foram avaliados o número de frutos, o número de pirênios e o número de pirênios por fruto em 56 genótipos ao longo de quatro safras (2020-2023), em um plantio experimental estabelecido em 1999, no Distrito Federal. Foram registrados: a produção anual de frutos; a altura total da planta, o diâmetro na base do tronco e a área da copa. A análise de variância (ANOVA) foi aplicada para avaliar as diferenças na produção de frutos entre anos, genótipos e quadrantes ao nível de significância de 5%. Estimaram-se os índices de repetibilidade (r) para as características relacionadas à produção, bem como o número de anos necessários para uma avaliação fenotípica eficiente. Houve alta variabilidade na produção de frutos, tanto entre os genótipos quanto entre os anos. Quatro genótipos se destacaram pelo alto potencial produtivo. A estimativa indicou que seriam necessários três anos para alcançar uma acurácia de 0,80 e quatro anos para 0,85. Embora a contagem de frutos por quadrantes tenha apresentado baixa acurácia para genótipos individuais, mostrou-se útil para estimativas de produção total, especialmente ao se avaliar um conjunto de genótipos. A área da copa apresentou correlação significativa com a produção de frutos.

Tropical forage seed production is strategically important to Brazil, and integrated crop-livestock-forest systems create a continuous demand for superior Urochloa ruziziensis cultivars. Optimizing commercial seed yield and quality is challenging, due to the inherent complexity of reproductive traits, seed dormancy, and highly variable seed filling. This study aimed to assess the phenotypic variability and correlations among 24 U. ruziziensis genotypes previously selected for high forage yield. Plants were evaluated for key flowering traits, filled seed mass, seed filling percentage, seed viability, germination rates, and seed dormancy. The results confirmed the existence of broad and significant phenotypic variability among the tested genotypes across all components of yield, quality, and dormancy, showing substantial potential for genetic improvement. Crucially, strong positive correlations were established between essential flowering components, such as the number of inflorescences per plant, and subsequent filled seed mass and seed viability. This study successfully identified elite genotypes exhibiting superior combined yield and quality, as well as specific genotypes with notably low dormancy. The identified genetic diversity and trait correlations provide criteria for guiding selection efforts in similar environments for U. ruziziensis breeding programs.

Gamba grass (Andropogon gayanus Kunth) is a promising forage alternative for Brazil’s Cerrado regions, attracting increasing research interest due to its potential to complement or replace widely planted species such as Urochloa and Megathyrsus. Despite the release of three cultivars, significant improvements in dry matter (DM) yield and forage quality are needed to fully realize its agronomic potential. This study aimed to evaluate genetic variability, estimate narrow sense heritability, and predict expected genetic gains for DM yield and key forage quality traits in two gamba grass populations derived from the cultivars BRS Sarandi and Planaltina. Trials were established in spring 2017 in Planaltina, DF, and evaluated during February–March 2018 and January–March 2019. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose (CEL), and hemicellulose (HEMIC) were quantified alongside DM yield. BRS Sarandi exhibited higher CP (12.3% vs. 9.8%) and lower NDF (57.1% vs. 63.4%), ADF (36.2% vs. 41.5%), CEL (20.8% vs. 23.7%), and HEMIC (20.9% vs. 21.9%) compared to Planaltina, while DM yield did not differ significantly between populations (4.57 t·ha⁻¹ vs. 4.50 t·ha⁻¹ per harvest, p > 0.05). Heritability estimates for individual harvests ranged from 0.31 to 0.68 for DM yield and 0.28 to 0.62 for quality traits, whereas multi-harvest models across years yielded lower estimates (0.07–0.27). Expected annual genetic gains were modest, with the highest predicted increase for CP (0.45% per year) and the largest decrease for NDF (−0.78% per year), reflecting the quantitative nature of trait inheritance and strong environmental influence. This study provides novel insights by simultaneously comparing two populations for multiple harvests and quantifying both yield and detailed forage quality traits, offering practical guidance for gamba grass breeding strategies. Results indicate that breeding programs should prioritize multiple selection cycles, precise phenotyping, genotypic and potentially genomic selection to accelerate improvement in both DM yield and forage quality, overcoming the constraints of low heritability and multi-trait selection.

Gamba grass, a leading alternative for forage development in Brazil Cerrado’s areas, has received a more extensive researchers' attention in the recent years. Although three cultivars were already released, for gamba grass to be an alternative to most planted forage species in Brazil (Genera Urochloa and Megathyrsus), significant technological improvements need to be achieved, mainly in genetic development of DM yield and forage quality. Understanding genetic variability of populations and the nature of the gene action governing the inheritance of traits are important contexts to obtain genetic gains from selection in breeding programs. The objective was to estimate DM yield and quality traits narrow-sense heritability and expected gains from HS family tests of two populations originated from the cultivars BRS Sarandi and cv. Planaltina. The trials were established in spring 2017 in Planaltina, DF and evaluated in February and March, 2018 and January, February, and March, 2019. Cultivar BRS Sarandi presented better forage quality than did cv. Planaltina due to higher CP and lower NDF, ADF, CEL, and HEMIC contents, and they did not differ for DM yield. Heritability estimates were low to moderate in magnitude for both populations, ranging from 0.31 to 0.68 for individual harvests and from 0.07 to 0.27 for models across harvests and years. Similar low h2 magnitudes across harvests and years were also observed for all quality traits estimated for both populations. The theoretical expected gains per year for all traits reflected modest gains, but all aligned with those from literature. The nature of the genetic variation is quantitative for all studied traits, since they were highly influenced by the environment. Results suggest more elaborated breeding methods, more cycles of selection, and more accurate measurement techniques to improve chances of success when breeding gamba grass for yield and quality. Alternatively, the use of genomic selection may promote a faster improvement of DM yield and forage quality traits, to overcome the constraints of low heritability, number of selection cycles, high costs, and multi-trait selection.

Gamba grass (Andropogon gayanus Kunth) is a tussock-forming forage species adapted to acid soils of Brazilian savannas and cultivated for grazing pastures. Four decades since its release, Planaltina prevails as the most commercialized cultivar of the species, even though the new cultivar BRS Sarandi could be a better alternative for Gamba-grass-based farms by presenting a greater leaf:stem ratio. The objective of this study was to evaluate the average daily live weight gain (ADG) of Nellore bulls (Bos indicus) for two Gamba grass cultivars—Planaltina and Sarandi. The experiment was conducted in Planaltina, Federal District, Brazil, for 3 years, namely 2018, 2018–2019, and 2020. The experimental design was a completely randomized block design with two treatments and three replicates, each one continuously stocked at three stocking rates (SR)—1.3, 2.6, and 4 young bulls/ha. Canopy height (CH), forage mass (FM), plant-part proportion (green leaf, stem, and dead material), and nutritive value were evaluated. In 2018, mean ADG for Sarandi pastures was greater (0.690 kg/bull/d) than that of Planaltina (0.490 kg/bull/d) (p < 0.10). In the subsequent year (2018–2019), there was no effect of cultivar (p > 0.10), while in 2020 the ADG was again affected by cultivar (p < 0.10), confirming the advantage of Sarandi (0.790 kg/bull/d) over Planaltina (0.650 kg/bull/d). In 2018 and 2020, the percentage of stems for Sarandi was about 3–6 pp less than for Planaltina (p < 0.10). As well as for stems, Sarandi pastures presented a shorter CH in 2028 and 2020 (6–7%) (p < 0.10). The positive high correlation of leaf:stem ratio with ADG (r = 0.70) probably predisposed the superiority of Sarandi over Planaltina. The distinguishing plant-part composition of Sarandi canopy promotes increasing weight gain of beef cattle when compared to cv. Planaltina.

Gamba grass (Andropogon gayanus Kunth) is a tussock-forming forage species adapted to acid soils of Brazilian savannas and cultivated for grazing pastures. Four decades since its releasing, Planaltina prevails as the most commercialized cultivar of the species, even though the new cultivar BRS Sarandi could be a better alternative for Gamba grass-based farms by presenting greater leaf:stem ratio. The objective of this study was to evaluate the average daily live weight gain (ADG) of Nellore bulls (Bos indicus) for two Gamba grass cultivars – Planaltina and Sarandi. The experiment was conducted in Planaltina, Federal District, Brazil, during 3 years, namely 2018, 2018-2019 and 2020. The experimental design was completely randomized block with two treatments and three replicates, each one continuously stocked at three stocking rates (SR) - 1.3, 2.6 and 4 young bulls/ha. Canopy height (CH), forage mass (FM), plant-part proportion (leaf, stem and dead material) and nutritive value were evaluated. In 2018, mean ADG for Sarandi pastures was greater (0.690 kg/bull/d) than Planaltina (0.490 kg/bull/d) (P=0.0839). In the subsequent year (2018-2019), there was no effect of cultivar (P = 0.4089), while in 2020 the ADG was again affected by cultivar (P=0.0412), confirming the advantage of Sarandi (0.790 kg/bull/d) over Planaltina (0.650 kg/bull/d). In 2018 and 2020, the percentage of stems for Sarandi was about 3-6 pp lesser than for Planaltina (P

Stylosanthes scabra Vogel is a tropical legume grown in dry tropical and subtropical environments. The objective of this research was to evaluate the genetic diversity of forage quality traits for 80 accessions of S. scabra. Seven plants from each accession were planted in a single-line plot with no replicates at Embrapa Cerrados, Brazil. All plants were harvested 90 days after planting. Crude protein (CP), in vitro dry matter digestibility (IVDMD), neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin (LIG), hemicellulose (HEMIC) and cellulose (CELLU) were estimated. Data were submitted to principal component analysis (PCA) and a cluster analysis was performed to identify groups of similarity. Simpson and Shannon–Weaver diversity indices estimated the genetic diversity. The average values of CP, IVDMD, NDF, ADF, LIG, HEMIC and CELLU were 220g/kg, 560g/kg, 516.8g/kg, 368g/kg, 69.4g/kg, 148.8g/kg and 298.6g/kg, respectively. There was a significant difference among collection sites for IVDMD, ADF and CELLU. The first two principal components accounted for 73% of the total variation. The 80 accessions resulted in four clusters, among which significant differences were observed for CP, IVDMD and ADF. Group IV, with 24 accessions, had the highest CP and IVDMD concentrations and the lowest ADF concentration, being the highest-quality forage group. Diversity indices were 0.78 and 0.81 for Simpson’s and Shannon–Weaver’s, respectively. In conclusion, there is genetic diversity for forage quality traits among S. scabra.

The use of stylosanthes in mixed grass‐legume pastures may minimize the decline in forage quality and quantity that occurs in monoculture grass pastures, even though the availability of commercial cultivars in Brazil is still limited. The objective of the study was to evaluate the liveweight (LW) gain of young Nellore bulls in a mixed pasture of Brachiaria brizantha (cv. Paiaguás) with the latest release Stylosanthes guianensis cv. Bela. The study was conducted in Planaltina, FD, Brazil, from September to August in two consecutive years, right after seeding. The experimental design was a randomized complete block design with two treatments (mixed or monoculture Paiaguás pastures) and three replicates. The average daily gain (ADG) was on average greater in mixed pastures (0.436 vs. 0.350 kg head⁻¹ day⁻¹ in mixed and grass pastures respectively), particularly in the dry period (0.344 vs. 0.183 kg head⁻¹ day⁻¹). The benefit of mixed over monoculture grass pastures throughout the year was 22 kg LW/head and 55 kg LW/ha. The presence of stylosanthes increased the crude protein (CP) concentration in mixed pastures (120 g/kg) when compared to monoculture grass pastures (109 g/kg), probably influencing the ADG of bulls. The increase of liveweight gain, predominantly in the dry season, makes the high‐protein stylosanthes cv. Bela an alternative to buffer the seasonal deficit of forage quality in newly seeded grass pastures.

New highly productive guineagrass (Megathyrsus maximus syn. Panicum maximum) cultivars have been released in Brazil and grazing trials are necessary to evaluate their carrying capacity and forage quality. The objective of this study was to evaluate the liveweight gains of young Nellore bulls grazing 3 guineagrass cultivars under rotational stocking. The experiment was carried out in Planaltina (Federal District, Brazil) during a single rainy (November‒April) and dry (May‒August) season. Treatments were Massai (control), BRS Tamani and BRS Zuri cultivars. Zuri and Tamani pastures provided greater average daily liveweight gains (ADG) (0.38 and 0.42 kg/head, respectively) over the experimental period than Massai (0.28 kg/head). For all cultivars liveweight gains decreased markedly from May onwards at the beginning of the dry season. Nevertheless, bulls grazing Tamani and Zuri pastures still gained 0.20 kg/hd/d until late August, while those on Massai pastures gained only 0.08 kg/hd/d. The differences in ADGs can be explained to some extent by differences in quality of available forage. In vitro dry matter digestibility of plucked samples of Massai was 555 g/kg, compared with 621 g/kg for Tamani and 590 g/kg for Zuri. Crude protein concentration in plucked samples was also greater for Tamani and Zuri (71.9 and 74.2 g/kg, respectively) than for Massai (62.2 g/kg). As feed wastage was particularly high in Massai, further studies are needed to verify if higher stocking rates during the wet season could result in greater production of live weight per ha on this cultivar, assuming that ADG does not decrease further with the increased stocking rate.