Assessment of spray deposition, drift and mass balance from unmanned aerial vehicle sprayer using an artificial vineyard.

Under the rapid development of unmanned aerial vehicle (UAV) plant protection products (PPP) application in Asian countries, the drift risk of UAV sprayer operation in orchard or vineyard is fairly high because of the much finer droplets generated and the higher height than ground sprayers, increasing threats to non-targeted crop, human and environment. However, there is few of comprehensive experimental study on the effects of UAV type and nozzle type on spray deposition and drift from UAV sprayer. The objectives of this study were to compare the spray performance of three different typical commercial UAV types (helicopter, 6-rotor and 8-rotor) with two nozzles types (hollow cone nozzle, HCN and air-injector flat fan nozzle, AIN) in vineyard. An artificial vineyard and three vertical collection frames, designed and built by ourselves, were applied for collecting droplets together with PVC collectors, petri dishes and rotary samples. The characteristics of deposition, drift and mass balance of UAV aerial spraying in vineyard were analyzed. As a result, under the crosswind speed of 3.11-3.79 m/s, AIN promoted spray deposition and uniformity and reduced drift significantly compared to HCN for all tested UAVs, improving of the utilization of PPP. The fitted regression functions of the sedimenting and airborne drift were obtained, respectively, and the drift percentage reduction values of AIN compared to HCN determined based on those functions varied from 81% to 95%. With HCN, 49.3%-73.4% of measured droplets drifted into non-targeted area and the highest proportion of drift loss was found for the airborne spray drift. According to the principle of more deposition and less drift, the spray performance of the three UAVs can be ranked in an order of 6-rotor, 8-rotor and helicopter, and two main reasons causing the difference in spray performance were the vortex airflow and the nozzle arrangement.

Non-Destructive Sensor-Based Prediction of Maturity and Optimum Harvest Date of Sweet Cherry Fruit.

(1) Background: The aim of the study was to use innovative sensor technology for non-destructive determination and prediction of optimum harvest date (OHD), using sweet cherry as a model fruit, based on different ripening parameters. (2) Methods: Two cherry varieties in two growing systems viz. field and polytunnel in two years were employed. The fruit quality parameters such as fruit weight and size proved unsuitable to detect OHD alone due to their dependence on crop load, climatic conditions, cultural practices, and season. Coloration during cherry ripening was characterized by a complete decline of green chlorophyll and saturation of the red anthocyanins, and was measured with a portable sensor viz. spectrometer 3-4 weeks before expected harvest until 2 weeks after harvest. (3) Results: Expressed as green NDVI (normalized differential vegetation index) and red NAI (normalized anthocyanin index) values, NAI increased from -0.5 (unripe) to +0.7 to +0.8 in mature fruit and remained at this saturation level with overripe fruits, irrespective of variety, treatment, and year. A model was developed to predict the OHD, which coincided with when NDVI reached and exceeded zero and the first derivative of NAI asymptotically approached zero. (4) Conclusion: The use of this sensor technology appears suitable for several cherry varieties and growing systems to predict the optimum harvest date.

Targeted forcing improves quality, nutritional and health value of sweet cherry fruit.

BACKGROUND: Trade and consumers alike require premium-quality cherries with high nutritional and health values preferably of local origin. While early fruit imports cannot supply such fruit, a new technology of forcing cherry emerged for an early local supply by covering the crop in spring. In the apparent scarcity of data on the resulting fruit quality, fruit characteristics of forced cherries were compared with those without cover. RESULTS: Size and weight of forced cherry fruit were successfully increased by 6-14%. The less negative osmotic potential of the forced fruit (-3 to -2 MPa Ψπ ) indicates less water stress under spring cover compared with field-grown fruit (-4 MPa Ψπ ), as confirmed by the larger fruit size and weight. Greater antioxidative potentials in the lipophilic and hydrophilic extracts (control min. 185 mE vs max. 365 mE under cover) of forced fruit of two cultivars showed their healthier attribute in terms of bioactive compounds, supported also by an average 14% increase in phenolics, as a response to the modified environmental conditions, which has not been investigated before. CONCLUSION: The new technology of covering cherry trees in spring to force flowering and enhance ripening can improve the synthesis of bioactive compounds and provide the consumer with early high-quality fruit. © 2017 Society of Chemical Industry.

Reflective mulch enhances ripening and health compounds in apple fruit.

BACKGROUND: The objective of the study was to improve fruit quality, including health compounds, by improving light utilization for fruit crops under hail net. Four reflective mulches including plastics such as Extenday® and a bio-degradable paper were spread in the alleyways of a cv. 'Gala Mondial' apple orchard on 10 August 2010 5 weeks before anticipated harvest. RESULTS: Reflective mulch affected neither fruit firmness nor sugar, but accelerated starch breakdown, indicative of riper fruits (smaller Streif index), compared with the uncovered grass alleyway (control). Reflective mulches also improved fruit quality such as red coloration of cv. 'Gala Mondial' apples. This was due to significantly enhanced flavonoids and anthocyanins. Flavonoids increased up to 52.4% in the Extenday® treatment (29.2 nmol cm(-2) in the grass control versus 44.5 nmol cm(-2) fruit peel with reflective mulch). Similarly, reflective mulch improved anthocyanin content in cv. 'Gala Mondial' peel up to 66% compared to grass control (14.5 nmol cm(-2) in control fruit versus 24.1 nmol cm(-2) with reflective mulch). The reflective mulch did not affect chlorophyll and carotenoid content in the 'Gala' fruit peel. CONCLUSION: Overall, the application of reflective mulches improved fruit quality in terms of better coloration and health compounds and accelerated ripening, leading to higher market value.