ABSTRACT
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.
ABSTRACT
The Intergovernmental Panel on Climate Change (IPCC) has pointed out the high vulnerability of developing countries to climate change, which is expected to impact food and income security. Sheep farming is one of the main animal productions among the families located in the most vulnerable regions of the semiarid region of Pernambuco state, a Brazilian territory known for its high temperatures, low relative humidity, and high net solar radiation. Therefore, the objective of this study was to identify different regions of Pernambuco that may be more suitable for different breeds of sheep, based on non-parametric statistics and kriging maps of the temperature and humidity index (THI). THI values were determined based on mean annual temperature and wind speed extracted from the TerraClimate remote sensing database. Pernambuco state presented THI values ranging from 66 to 79, with the hair breeds having a high potential for exploitation in almost all territories, including the main meat-producing breeds. The East Friesian breed, a high milk producer, would be well suited to the Agreste mesoregion, a territory that, like the Pajeú and Moxotó microregions, also proved favorable for the introduction of three wool breeds (Suffolk, Poll Dorset, and Texel) known as major meat producers. The kriging maps of the THI values successfully allowed the identification of strategic development regions of Pernambuco state with high potential for sheep breeding.
ABSTRACT
Plants with the crassulacean acid metabolism commonly present good adaptation to arid and semi-arid environments, but it highly depends on the type of species. In this study, chlorophyll fluorescence, the concentration of inorganic and organic solutes and the productive performance were evaluated along with their relationships in different clones of the genera Opuntia and Nopalea. The experiment was conducted from 2016 to 2018. Four clones of genus Opuntia were evaluated: 'Orelha de Elefante Mexicana' (OEM), 'Orelha de Elefante Africana' (OEA), V19 and F8; and two clones of genus Nopalea: 'IPA Sertânia' and 'Miúda'. The experiment was arranged in a randomised block design, with six treatments and three replications. The following parameters were measured when harvesting: initial, maximum and variable fluorescence; the quantum yield of PSII (Fv/Fm); light-induction curves of the photochemical parameters (ΔF/Fm', qP, NPQ and ETR); the chlorophyll and carotenoid content; carbohydrates; the sodium (Na+) and potassium (K+) content; morphometry; and dry matter accumulation. The values for the effective quantum yield of PSII (ΔF/Fm') and the alterations in photochemical quenching were higher in the OEM clone (P < 0.05). There was a difference between clones for non-photochemical quenching, with the F8 clone having the highest values. The Fv/Fm was 0.87 for the OEM. 'IPA Sertânia' obtained the greatest Chl a/b, and the highest values for carbohydrate concentration were found in the OEA clone. The OEM clone showed the greatest accumulation of K+, in addition to a higher cladode area index and greater dry matter accumulation. The results of this study show the high physiological tolerance of the forage cactus to a semi-arid environment, which varies according to the clone.
