Índice de área foliar da cana de açúcar sob dois sistemas de cultivo.

Objetivou-se analisar a influência da presença de palhada em solo no índice de área foliar da cana-de-açúcar irrigada no Semiárido brasileiro. O experimento foi conduzido entre 21/08/2015 e 28/07/2016, no município de Juazeiro, Bahia, onde dois talhões de 5,0 ha foram mantidos sem e com a presença de palhada. No talhão com a palhada foi mantida uma cobertura de 27,2 Mg ha-1, oriunda do próprio corte da cultura. A variedade VAT 90-212, durante o seu terceiro ciclo, foi monitorada em 14 datas com medições de um medidor portátil do índice de área foliar. Os dados foram submetidos ao teste não paramétrico de Mann-Whitney. A manutenção da palhada em campo afetou o índice de área foliar (IAF) (p 0,05). Um novo crescimento da cultura foi verificado após ocorrência do tombamento, o que resultou em nova diferença entre esses cultivos, ao final do ciclo. Conclui-se que, a manutenção da palhada reduziu o IAF da cana-de-açúcar, variedade VAT 90-212, no Semiárido brasileiro, sobretudo devido os impedimentos promovidos no início do ciclo e o tombamento da cultura

Morphophysiological indicators, phenophase and cutting time in an irrigated forage cactus–sorghum intercropping system under strategies of agricultural resilience and agriculture biosaline.

The objective of this study was to evaluate growth and development in an irrigated forage cactus–sorghum intercropping system under different strategies for improving agricultural resilience. The research was carried out from 2018 to 2020 in Serra Talhada, Pernambuco, Brazil, in four experiments in a randomized block design, each with four replications. The first experiment consisted of different configurations for the cactus–sorghum intercropping system (Orelha de Elefante Mexicana [OEM]-single crop [SNG], IPA Sertânia [IPA]-SNG, Miúda [MIU]-SNG, OEM–SF11, OEM–Progenitor 288 [P.288], OEM–467, IPA–SF11, IPA–P.288, IPA–467, MIU–SF11, MIU–P.288 and MIU–467); in the second and third experiments, the cactus–sorghum system was planted under different planting densities (100,000; 50,000; 33,333; 25,000 and 20,000 plants ha−1 for forage cactus and 200,000 plants ha−1 for sorghum) in east–west and north–south orientations, respectively; and the fourth experiment consisted of different planting densities for the cactus and sorghum (50,000; 40,000; 33,333; and 28,571 plants ha−1 and 200,000; 160,000; 133,333; and 114,285 plants ha−1, respectively). The maximum values of the dry matter accumulation rate were observed in the cultivation configurations that contained the OEM clone and at the highest densities. The different cultivation configurations affected the duration and number of phenophases. The cutting time increases as the planting density increases (50,000 and 100,000 plants ha−1) and when the OEM clone is used.On-line

Avanço da agrometeorologia da palma forrageira: radiação fotossinteticamente ativa interceptada e absorvida pela cultura.

Resumo: A palma é a cactácea forrageira mais cultivada no mundo, todavia, ainda negligenciada do ponto de vista de mudanças do uso da terra. A interação de uma superfície e a atmosfera varia com o tipo de interface (solo-planta-clima). Para este tipo de inferência, a radiação fotossinteticamente ativa interceptada ou absorvida é mundialmente usada. Pouco se dispõem de dados de interceptação ou absorção de radiação pela palma. Neste estudo, objetivou-se mensurar a fração e a quantidade de radiação fotossinteticamente interceptada e absorvida por esta espécie ao longo do ciclo. O experimento foi conduzido no município de Serra Talhada, PE, em uma área de 1,1 hectare de palma. Medidas de radiação solar global incidente e refletida, radiação fotossinteticamente ativa acima e abaixo da cultura, dados meteorológicos de uma estação do Instituto Nacional de Meteorologia e de índice de área do cladódio (IAC) foram usados nesta pesquisa. Equações foram geradas utilizando como variável independente o tempo térmico (TT, oC dia). Observou-se três fases de acúmulo de radiação interceptada e absorvida pela palma, em resposta ao incremento do IAC. Ao final de 482 dias, a palma interceptou 1902 MJ m-2 dos quais 1461 MJ m-2 foram absorvidos, correspondendo a 73% e 62% da radiação fotossinteticamente incidente acima da cultura, nesta ordem. Esta informação é essencial para o avanço da pesquisa de modelagem da palma forrageira

How to enhance the agronomic performance of cactus-sorghum intercropped system: planting configurations, density and orientation.

Clarifying cultivation techniques and making production systems more efficient are practices that have been much sought after in agricultural systems in recent decades. In this context, the forage yield, biological efficiency, and competitive ability, of different cultivation strategies for intercropping forage cactus and sorghum were determined in biosaline production systems from 2018 to 2020 in Brazil. Four experiments were carried out, comprising: 1) cropping configurations for the forage cactus-sorghum intercropping system; 2 and 3) planting densities for the forage cactus intercropped with sorghum with an east-west and north-south row orientation, respectively; and 4) planting densities for the forage cactus and sorghum. Each experiment used a randomised block design with four replications. The intercropped forage cactus and sorghum showed higher productivity than the monocropped systems. The indices of biological efficiency (LER, ATER, LEC and SPI with mean values equal to 1.6, 1.8, 0.6 and 29.0, respectively) and competitive ability (ALGY in average 870.6) show better performance under the intercropped system compared to the single crops. The increased planting density resulted in an increase in productivity under the intercropped forage cactus-sorghum system (on average an increase of 69.4% dry matter). In turn, the orientation had no influence on the productivity of the intercropping system but offered better conditions for the forage cactus when cultivation was in an east-west direction (21.7 Mg ha􀀀 1 of dry matter) compared to north-south (17.5 Mg ha􀀀 1 of dry matter). Intercropping forage cactus and sorghum using biosaline agriculture is an excellent alternative for a production system in semi-arid environments, especially at higher planting densities (50,000 and 100,000 plants ha􀀀 1)

The use of mulch in cultivating the forage cactus optimizesyield in less time and increases the water use efficiency ofthe crop.

Measurements of crop evapotranspiration (ETC) and crop coefficients (kC)incactus have not yet been adjusted for the phenological stage using conserva-tion practices (i.e. mulching). In this study, soil water dynamics, ETCandkCwere measured in the forage cactus under cultivation systems with (WM) andwithout (NM) the use of mulch in the semi-arid region of Brazil.Opuntiastrictawas subjected to irrigation depths based on a percentage of the referenceevapotranspiration (ET0) (rainfed, 25, 50, 75 and 100%) and to two systems ofcultivation: WM and NM. Over time, the phenophases (?Ph) were established;the soil water balance components were calculated and the crop yield wasevaluated at harvest. The use of 8.2 Mg ha1mulch led to almost no reducedwater consumption by the crop when compared to the NM system; however,the mulch did maximize yield, at 839C day, when irrigated with 50% ET0. ThekCvalue was higher under the WM system, with the differences decreasingthroughout the cycle (?PhI, 36%;?PhII, 27%;?PhIII, 23%;?PhIV-HT, 17%; and?PhIV-RF, 14%). Therefore, the use of mulch in cultivating the cactus opti-mized forage production in less time and significantly increased the water useefficiency of the cro

Integrated management of agronomic practices in the forage cactus: maximizing productivity, biological efficiency and economic profitability.

Forage cactus cropping systems that include a combination of agricultural practices (cloning, irrigation, mulching, and/or intercropping) can increase forage production and economic return in semi-arid environments. This study evaluated the effect on productivity, biological efficiency, and economic return of combining different practices with forage cactus cropping systems in the semi-arid region of Brazil. The research was conducted in four experimental areas, in a randomized block design with four replications, and included the following practices: 1) clones – irrigation - cover, 2) different irrigation depths, 3) intercropping - mulching, and 4) different levels of mulch. The treatments in experiment I consisted of three cactus clones (‘Orelha de Elefante Mexicana’—OEM; ‘Miúda’—MIU and ‘IPA-Sertânia’—IPA), two water regimes (rainfed and irrigated), and two levels of mulch (with and without mulch). Experiment II comprised four irrigation depths (0, 40, 80, and 120% of the crop evapotranspiration) and three cactus clones. In experiment III, three crop arrangements (single cactus, cactus intercropped with millet, and single millet) were evaluated under two levels of mulching (with and without mulching). In experiment IV, four levels of mulch were used (0, 5, 10, and 15 Mg ha-1). The total number of cladodes per plant, fresh matter yield (YFM), dry matter yield (YDM), and final plant density were obtained when harvesting. Economic viability was assessed using the profitability index (PI). The rainfed systems showed greater yield. The use of mulch afforded greater productivity. The OEM clone (YFM = 310.76 Mg ha-1 and YDM = 29.87 Mg ha-1) obtained a higher yield than did the IPA and MIU clones. The highest PI values were achieved under the rainfed systems. The MIU and IPA clones exhibited lower PI values. The cactus-millet intercrop achieved the best performance with the use of mulch. Cactus systems of 15.0 Mg ha-1 showed a greater PI value. It was concluded that the integrated management of such practices as intercropping, mulching, and the adoption of the OEM clone can increase the supply of forage. These practices can promote the sustainable intensification of forage input in Livestock Production Systems in semi-arid environments

Monitoring energy balance, turbulent flux partitioning, evapotranspiration and biophysical parameters of Nopalea cochenillifera (Cactaceae) in the Brazilian Semi-Arid environment.

The in-situ quantification of turbulent flux and evapotranspiration (ET) is necessary to monitor crop performance in stressful environments. Although cacti can withstand stressful conditions, plant responses and plant?environment interactions remain unclear. Hence, the objective of our study was to investigate the interannual and seasonal behaviour of components of the surface energy balance, environmental conditions, morphophysiological parameters, biomass yield and water relations in a crop of Nopalea cochenillifera in the semi-arid region of Brazil. The data were collected from a micrometeorological tower between 2015 and 2017. The results demonstrate that net radiation was significantly higher during the wet season. Latent heat flux was not significant between the wet season and dry season. During the dry-wet transition season in particular, sensible heat flux was higher than during the other seasons. We observed a large decline in soil heat flux during the wet season. There was no difference in ET during the wet or dry seasons; however, there was a 40% reduction during the dry-wet transition. The wet seasons and wet-dry transition showed the lowest Evaporative Stress Index. The plants showed high cladode water content and biomass during the evaluation period. In conclusion, these findings indicate high rates of growth, high biomass and a high cladode water content and explain the response of the cactus regarding energy partitioning and ET

Sink or carbon source? how the Opuntia cactus agroecosystem interacts in the use of carbon, nutrients and radiation in the Brazilian semi-arid region.

Anthropogenic disturbances directly influence environmental processes and increase the concentration of carbon (C) in the atmosphere. Here, we compare the differences in the seasonality of the balance of carbon, energy, and radiation, as well as seek to identify the interrelationships between these environmental variables and their impact on the growth of Opuntia cactus. Data were acquired from an eddy covariance flux tower over a cactus crop agroecosystem (2019–2021) in the Brazilian semi-arid region. In addition, we use plant growth rates, carbon and nutrient stocks, evapotranspiration (ET) and water use efficiency (WUE), and radiation (RUE). We show that the closure of the surface energy balance was 71%, although there are minimal fluxes of available energy lost (29%) by unquantified processes. At all seasons, the highest net ecosystem CO2 exchange (NEE) rate was between 11:00–13:00 (�� 5.75 μmol m�� 2 s�� 1). During the dry and wet-dry season, there was the lowest daily gross primary productivity (GPP) (2.5 μmol m�� 2 s�� 1) and net radiation—Rn (217.97 W m�� 2). Ecosystem respiration was more expressive during the wet season (2.41 μmol m�� 2 s�� 1), and maximum diurnal value of 2.65 μmol m�� 2 s�� 1. Furthermore, the latent heat flux was higher during the wet season (114.68 W m�� 2) and lowered in the dry season (9.39 W m�� 2). The net assimilation rate showed higher values during the dry-wet transition. The dry season presented higher nutrient use efficiency and WUE (14.77 g m�� 2 mm�� 1). The highest ET occurred during the wet season (227 mm), and RUE was 81.48% higher than in the dry season. Overall, the cactus was a potential C sink during the three years of assessment (NEE: �� 377 g C m�� 2 year�� 1; GPP: 881 g C m�� 2 year�� 1). The results help us to understand that most of the Rn energy is used in the sensible heat flux (58% ratio)

Inventory and review of the Mio–Pleistocene São Jorge flora (Madeira Island, Portugal): palaeoecological and biogeographical implications

The occurrence of plant fossils on Madeira Island has been known since the mid-nineteenth century. Charles Lyell and George Hartung discovered a leaf bed rich in Lauraceae and fern fossils at S~ao Jorge in 1854. The determinations were controversial but a full review was never performed. Here we propose possible geological settings for the fossiliferous outcrop, and present an inventory and a systematic review of the surviving specimens of the S~ao Jorge macroflora. The S~ao Jorge leaf bed no longer outcrops due to a landslide in 1865. It was possible to establish the two alternative volcano stratigraphical settings in the sedimentary intercalations from the Middle Volcanic Complex, ranging in age from 7 to 1.8 Ma. The descriptions of Heer (1857), Bunbury (1859) and Hartung & Mayer (1864) are reviewed based on 82 surviving specimens. From the initial 37 taxa, we recognize only 20: Osmunda sp., Pteridium aquilinum, Asplenium cf. onopteris, aff. Asplenium, cf. Polystichum, cf. Davallia, Woodwardia radicans, Filicopsida gen. et sp. indet. 1 and 2, Ocotea foetens, Salix sp., Erica arborea, cf. Vaccinium, Rubus sp, cf. Myrtus, Magnoliopsida gen. et sp. indet. 1 to 3, Liliopsida gen. et sp. indet. 1. Magnoliopsida gen. et sp. indet. 4 is based on one previously undescribed flower or fruit. The floristic composition of the S~ao Jorge fossils resembles the current floristic association of temperate stink laurel (Ocotea foetens) forest, suggesting a warm and humid palaeoclimate and indicating that laurel forests were present in Macaronesia at least since the Gelasian, a time when the palaeotropical geofloral elements were almost extinct in Europe.info:eu-repo/semantics/publishedVersio