Investigation and analysis of an ultrasonic sensor for specific yield assessment and greenhouse features identification

The spectrum of an ultrasonic return echo from plants has been shown to contain useful information. The research reported in this paper focused on developing an ultrasonic sensing system and analyzing the ultrasonic classification features that would ultimately be used as the basis for a yield estimation robotic system. An algorithm was also developed for prediction of fruit mass per plant based on the ultrasonic echo return from a plant. The ultrasonic sensor system was tested in lab and pepper greenhouse environments and on single pepper plants, single leaves and fruit. The results showed the potential of ultrasonic sensors for such a robot in classifying plants and greenhouse infrastructures such as walls. It showed the robot’s ability to detect hidden plant rows and fruits as well as making an estimation of the fruit mass in single plants. A multi-linear regression model developed for estimating the energy level was found to be highly significant with R ² of 0.64 and 0.84 for 28–32 and 20–28 kHz ranges respectively. This estimated model was used to derive a prediction method for fruit mass per plant that yielded an R² of 0.34.     

Effects of supplementary pollination on cropping success and fruit quality in pistachio

The effects of pollen supplementation in pistachio orchards using an electrostatic pollination device were investigated in a 3‐year study (1996‐98) in San Joaquin Valley, California, USA. Both yield and fruit quality (per cent split fruit) were tested in several experiments. Applying smaller amounts of pollen (1.5 g per tree in early application only in 1996 or 0.5 g in two applications in 1997) resulted in higher yields than with open pollination or supplementary pollination using larger amounts of pollen (1.5 g per tree in four applications in 1996 or 1.0 g in two applications in 1997). Applying 1.0 g pollen in two applications in 1998 resulted in decreased yields compared with open pollination or non‐electrostatic pollination. Pollen germinability on the stigma was greatest for open pollination suggesting that overloading the stigmas with pollen in supplementary pollination may not only reduce yield but also increase competition between pollen grains. The per cent split fruit significantly increased only once in 1996. When pollination is a limiting factor, electrostatic pollination of pistachio can increase yield and may even increase fruit quality. However, when pollination is not a limiting factor, electrostatic pollination may even reduce yield.     

Improving pollination of almond (Amygdalus communis L., Rosaceae) using electrostatic techniques

Summary

Supplementary pollination of almond using electrostatic techniques was tested in a three year study (1996–1998) in Northern Israel. We used an electrostatic pollination device and tested its effects on fruitlet set, fruit set, yield weight and nut weight. We also tested its ability to pollinate flowers on the tree from the distal to the proximal part of the branches. We found that when individual branches were pollinated, fruitlet set was in accordance with the expected deposition rate of pollen grains on the stigma: electrostatic 1 open pollination > non-electrostatic + open pollination + open pollination > electrostatic pollination > non-electrostatic pollination > spontaneous self pollination. Fruit set results showed the same pattern but were not as precise. Electrostatic pollination of individual trees resulted in an insignificant increase in pollen germinability on the stigma. The highest germinability was on the distal part of the branch and the lowest was on the proximal part of the branch, in all pollination treatments. Electrostatic pollination increased yield as compared with non-electrostatic and open pollination. Nut weight, however, decreased slightly with increased yield. We suggest that electrostatic pollination can be an important method for pollen supplementation in almond orchards when honeybee pollination is insuf®cient and when the trees can withstand the added portion of nuts, resulting from improved pollination.     

Development of a robotic detection system for greenhouse pepper plant diseases

Automation of disease detection and monitoring can facilitate targeted and timely disease control, which can lead to increased yield, improved crop quality and reduction in the quantity of applied pesticides. Further advantages are reduced production costs, reduced exposure to pesticides for farm workers and inspectors and increased sustainability. Symptoms are unique for each disease and crop, and each plant may suffer from multiple threats. Thus, a dedicated integrated disease-detection system and algorithms are required. The development of such a robotic detection system for two major threats of bell pepper plants: powdery mildew (PM) and Tomato spotted wilt virus (TSWV), is presented. Detection algorithms were developed based on principal component analysis using RGB and multispectral NIR-R-G sensors. High accuracy was obtained for pixel classification as diseased or healthy, for both diseases, using RGB imagery (PM: 95%, TSWV: 90%). NIR-R-G multispectral imagery yielded low classification accuracy (PM: 80%, TSWV: 61%). Accordingly, the final sensing apparatus was composed of a RGB sensor and a single-laser-beam distance sensor. A relatively fast cycle time (average 26.7 s per plant) operation cycle for detection of the two diseases was developed and tested. The cycle time was mainly influenced by sub-tasks requiring motion of the manipulator. Among these tasks, the most demanding were the determination of the required detection position and orientation. The time for task completion may be reduced by increasing the robotic work volume and by improving the algorithm for determining position and orientation.     

Segmentation and motion parameter estimation for robotic Medjoul-date thinning

Precision Agriculture - Laborious fruit thinning is required for attaining high-quality Medjoul dates. Thinning automation can significantly reduce labor and improve efficiency. An image processing...