Oncideres saga Dalman: first record damaging Stryphnodendron adstringens Mart. Coville (Fabaceae) in Brazil

Oncideres females girdle tree branches of the Fabaceae family, interrupting the sap flow and turning the wood conditions ideal for their larvae development. The bark of Stryphnodendron adstringens (Mart.) Coville, a species native to the Brazilian Cerrado, is widely used in the traditional medicine. The objectives were to report, for the first time, Oncideres saga (Dalman), using S. adstringens as a host and to describe the pattern of branch girdling and oviposition distribution by this insect on these branches. The diameter at the base and the length of the girdled branches were measured and the number of incisions made by the O. saga females to oviposit, per branch section (basal, median and apical), counted. The emerged specimens were counted and the diameter of the exit holes measured. The average diameter at the base of the girdled branches was 2.5 ± 0.16 cm and the length was 90.6 ± 4.6 cm. The average number of incisions per branch was 37.7 ± 2.7. Damage by O. saga can reduce the growth and cause losses on S. adstringens, a tree with great extractivism potential.,

On the Use of Sap Flow Measurements to Assess the Water Requirements of Three Australian Native Tree Species

The measurement of sap movement in xylem sapwood tissue using heat pulse velocity sap flow instruments has been commonly used to estimate plant transpiration. In this study, sap flow sensors (SFM1) based on the heat ratio method (HRM) were used to assess the sap flow performance of three different tree species located in the eastern suburbs of Melbourne, Australia over a 12-month period. A soil moisture budget profile featuring potential evapotranspiration and precipitation was developed to indicate soil moisture balance while the soil-plant-atmosphere continuum was established at the study site using data obtained from different monitoring instruments. The comparison of sap flow volume for the three species clearly showed that the water demand of Corymbia maculata was the highest when compared to Melaleuca styphelioides and Lophostemon confertus and the daily sap flow volume on the north side of the tree on average was 63% greater than that of the south side. By analysing the optimal temperature and vapour pressure deficit (VPD) for transpiration for all sampled trees, it was concluded that the Melaleuca styphelioides could better cope with hotter and drier weather conditions.

Satellite-Based Water and Energy Balance Model for the Arid Region to Determine Evapotranspiration: Development and Application

Actual evapotranspiration (ETa) plays an important role in irrigation planning and supervision. Traditionally, the estimation of ETa was approximated using different in situ techniques, having high initial and maintenance costs with low spatial resolution. In this context, satellite imagery models play an effective role in water management practices by estimating ETa in small and large-scale areas. All existing models have been widely used for the estimation of ETa around the globe, but there is no definite conclusion on which approach is best for the hot and hyper-arid region of Oman. Our study introduces an innovative approach that uses in situ, meteorological, and satellite imagery (Landsat-OLI/TIRS) datasets to estimate ETa. The satellite-based water and energy balance model for the arid region to determine evapotranspiration (SMARET) was developed under the hot and hyper-arid region conditions of Oman by incorporating soil temperature in the sensible heat flux. The performance of SMARET ran through accuracy assessment against in situ measurements via sap flow sensors and lysimeters. The SMARET was also evaluated against three existing models, including the surface energy balance algorithm for land (SEBAL), mapping evapotranspiration at high-resolution with internalized calibration (METRIC), and the Penman–Monteith (PM) model. The study resulted in a significant correlation between SMARET (R2 = 0.73), as well as the PM model (R2 = 0.72), and the ETa values calculated from Lysimeter. The SMARET model also showed a significant correlation (R2 = 0.66) with the ETa values recorded using the sap flow meter. The strong relationship between SMARET, sap flow measurement, and lysimeter observation suggests that SMARET has application capability in hot and hyper-arid regions.

Sap Flow and Water Consumption of Captain Cook Tree [Cascabela thevetia (l.) Lippold].

A two-year field study documented the diurnal and nocturnal sap flow rates and water consumption of young (YCC), adult (ACC) and mature (MCC) Captain Cook trees [Cascabela thevetia (L.) Lippold] that were invading a riparian habitat in northern Queensland. For comparison, two native trees [black tea tree (Melaleuca bracteata F. Muell.) and Moreton Bay ash (Corymbia tessellaris (F.Muell.) K.D.Hill & L.A.S.Johnson)] growing in association with Captain Cook tree were also monitored. Sap flow measurements were grouped into eight timeframes per day (early morning, late morning, early afternoon, late afternoon, early night, late night, early dawn and late dawn). Significant interactions in sap flow rate occurred between plant types, timeframes, and months. The magnitude of sap flow rate was Moreton Bay ash>YCC>ACC>black tea tree>MCC. Maximum sap flow rates tended to occur during early (1-3 pm) to mid-afternoon (4-6 pm) for all age groups of Captain Cook tree and the two native trees. Diurnal sap flow rates were significantly greater than nocturnal, and on a monthly basis sap flow rates were highest over the spring to autumn period (September-May) and lowest during winter (June–August). Significant differences in water consumption also occurred between species and months. Water consumption peak time varied between plant types with most plants peaking in January except for MCC and Moreton Bay ash trees for which peak water consumption occurred in June and July respectively. Water consumption was high across all seasons except winter. The magnitude of water consumption was Moreton Bay ash>black tea tree>YCC>ACC>MCC trees. Moreton Bay ash registered maximal monthly water consumption (4700 L) compared with minimal consumption by MCC trees (55 L). On average, Captain Cook trees used 99% and 72% less water than Moreton Bay ash and black tea trees respectively. The significantly lower water consumption by Captain Cook trees compared with Moreton Bay ash and black tea trees may be offset by high population densities. Results also suggest that knowledge of optimal sap flow timeframes may be advantageous in exploring optimal timing for application of control operations related to management of Captain Cook trees.

Prediction of Grape Sap Flow in a Greenhouse Based on Random Forest and Partial Least Squares Models

Understanding variations in sap flow rates and the environmental factors that influence sap flow is important for exploring grape water consumption patterns and developing reasonable greenhouse irrigation schedules. Three irrigation levels were established in this study: adequate irrigation (W1), moderate deficit irrigation (W2) and deficit irrigation (W3). Grape sap flow estimation models were constructed using partial least squares (PLS) and random forest (RF) algorithms, and the simulation accuracy and stability of these models were evaluated. The results showed that the daily mean sap flow rates in the W2 and W3 treatments were 14.65 and 46.94% lower, respectively, than those in the W1 treatment, indicating that the average daily sap flow rate increased gradually with an increase in the irrigation amount within a certain range. Based on model error and uncertainty analyses, the RF model had better simulation results in the different grape growth stages than the PLS model did. The coefficient of determination and Willmott’s index of agreement for RF model exceeded 0.78 and 0.90, respectively, and this model had smaller root mean square error and d-factor (evaluation index of model uncertainty) values than the PLS model did, indicating that the RF model had higher prediction accuracy and was more stable. The relative importance of the model predictors was determined. Moreover, the RF model more comprehensively reflected the influence of meteorological factors and the moisture content in different soil layers on the sap flow rate than the PLS model did. In summary, the RF model accurately simulated sap flow rates, which is important for greenhouse grape irrigation.

Water Regime Monitoring of the Royal Walnut (Juglans regia L.) Using Sap Flow and Dendrometric Measurements

Changes in the distribution of annual rainfall totals, together with the increase in temperature over the last 40 years, are causing more frequent periods of drought, and plants are more often exposed to water stress. The aim of this study was to monitor the effect of different water regimes (irrigated and non-irrigated) of individuals of walnut tree (Juglans regia L.) in a private orchard located in the West of Slovakia. Our research was focused on dendrometric and sap flow measurements in the period from 28 March to 2 June 2019. The results showed differences in the sap flow of walnut trees during the budbreak period: when trees were irrigated, sap flow in the diurnal cycle was around 130 g·h−1 (20.48%), higher than in the non-irrigated treatment. Dendrometric differences between the irrigated and non-irrigated treatments were not significant. The sap flow data in the flowering period of the irrigated variant were slightly higher at 150 g·h−1 (35.62%) than non-irrigated. Dendrometric differences were more significant when the difference between the variants was more than 1.5 mm. Continuation of this research and analysis of the data obtained in the coming years will allow us to evaluate the effects of the environment on fruit trees in the long term.

Assessing water requirement of orange trees using sap flow measurements in Narkhed-Pandhurna critical zone observatory (CZO) in central India

We used thermal dissipation method for sap flux measurements in orange trees to assess its water requirement in Narkhed-Pandhurna region. Thermal Dissipation Probe (TDP) sensors were installed in 5-year old (young) and 15-year old (mature) orange trees to measure the diurnal sap flux variations in trees during November 21, 2019, to January 31, 2020 (71 days). The results show that the maximum daily water uptake by the 5-year old tree was 1.1 L observed on 39th day of measurement (December 29, 2019) and in the 15-year old tree it was 5.0 L, and it observed on 38th day (December 28, 2019) of measurement. The cumulative water uptake during the study period by the 5-year old tree was 49.0 L, and the 15-year old tree consumed 257.4 L of water. The results were compared with the recommended irrigational values of Indian Horticulture Board (IHB), Government of India (GoI) and Groundwater Survey and Development Agency (GSDA), Government of Maharashtra (GoMH) for orange orchards. The initial investigation shows that recommended guidelines for irrigation of orange trees are exorbitantly high and needs to be revised. The sap flow methods are more precise that can measure sap flow at a very short interval and can generate a time series of data. It can be used to revise the guidelines with the aim to conserve water and propose precision water irrigation for the study area in particular and different agro-climatic zones of the country in general.