Modeling Canopy Par Interception For Estimating Potential Yield In Almond And Walnut Trees
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Modeling Canopy PAR Interception for Estimating Potential Yield in Almond and Walnut Trees
A knowledge of spatio-temporal variability in potential yield is essential for site-specific nutrient management in crop production. The objectives of this project were: (i) to develop a model for photosynthetically active radiation (PAR) intercepted by almond and walnut trees based on data obtained from respective trees, (ii) estimate potential crop yield in individual or a block of five trees, and (iii) to analyze if the area of the shadows at any time can be obtained from aerial images. This project used proximally sensed PAR interception data measured using a lightbar mounted on a mobile platform, aerial images obtained from an unmanned aerial vehicle and a crop growth model to estimate potential crop yield of almond and walnut trees. Empirical and analytical models were developed to estimate PAR intercepted by the tree. Solar noon scans were collected in Nickels Soil Laboratory, Arbuckle, CA during the 2012, 2013 and 2014 growing seasons. Diurnal scans were also collected during the 2012 season and were used to validate the models. Diurnal scans were used to develop an empirical model, where the total amount of PAR intercepted by a tree at any time during the day was found to be a function of zenith angle and midday PAR interception. The latter can be measured using the mobile platform lightbar system or can be estimated using the seasonal growth curve. Midday PAR interception was found to increase only during the 2012 season. The model was validated with a coefficient of determination of 0.87 and 0.86 for almond and walnut trees, respectively. An analytical model was also developed, where tree canopy was assumed to be spheroidal in shape. PAR intercepted by a tree was estimated, taking into account the effect of row spacing, tree spacing within the row, latitude and longitude of the orchard, day of the year and row orientation. The model was validated with a coefficient of determination of 0.94 and 0.86 for almond and walnut trees, respectively. Our results showed that the total amount of PAR intercepted by the tree at any time during the day can be found analytically using one lightbar scan as a reference to estimate tree radius and optical density. A comparison between PAR interception data estimated analytically and empirically showed that both approaches had a similar behavior over the season. Both presented lower values of PAR intercepted in the early morning and late in the afternoon and reached a peak before and after solar noon.A strong correlation was also found between yield (for both actual and potential) and absolute midday PAR intercepted for both almond and walnut trees. Absolute values of midday PAR interception were better for predicting yield (both actual and potential) than the relative values of midday PAR interception. The coefficient of determination (r2) between actual yield and absolute midday PAR intercepted was 0.70 for both crops. The coefficient of determination values for the relationship between actual and potential yield were 0.62 and 0.59 for almond and walnut crops, respectively. A quadratic behavior was found for the relationship between potential yield and absolute midday PAR interception. Canopy shaded area was found to be correlated with PAR interception and the zenith angle. Coefficients of determination of 0.92 and 0.88 were found for the relation between measured and estimated values of PAR intercepted for almond and walnut trees, respectively. Furthermore, the shaded area at any time was found to be correlated with the area of the canopy extracted from an aerial image and the zenith angle. Coefficients of determination of 0.81 and 0.89 were found for the relationship between measured and estimated values of shaded area for almond and walnut trees, respectively. Additionally, PAR interception was found to be related to the canopy volume measured by a LIDAR system. Coefficients of determination of 0.75 and 0.77 were found for blocks of five almond and walnut trees, respectively. These results suggest that growers could improve their prediction capabilities for potential yield and use this information to implement site specific fertilization management at a scale of five trees. Additionally, these models could also be employed in the planting/replanting stage to obtain the orchard configuration that optimizes light capture and potential yield.
Automation in Tree Fruit Production
Automation in agriculture is made possible by the integration of advanced agricultural technology and precision agriculture management. This book, uniquely, will focus on applications of automation to the important industry of tree fruit production. Written by experts in agricultural automation technology from around the world, chapters in this book cover topics such as automated tree fruit production systems, plant stress sensing and high-throughput phenotyping in precision horticulture, the economics of automation in tree fruit production, light interception sensing systems for canopy management, precision irrigation and water management, precision technologies for pest and disease management, opportunities for the application of robotics in tree fruit production, and the mechanical harvesting and handling of fruit crops. The book is a representative, concise overview of the variety of technologies currently being applied to tree fruit crops around the world and the challenges faced by engineers and farmers that these technologies raise. It is aimed at researchers and graduate students of agriculture systems, agricultural and biological engineering, crop and soil sciences, horticulture, precision agriculture, and other relevant disciplines. It will also be of use to agriculture consultants, engineers, and other professionals such as agricultural equipment manufacturers and management professionals who use precision agriculture technologies.
Achieving sustainable cultivation of tree nuts
Author: Prof Ümit Serdar
language: en
Publisher: Burleigh Dodds Science Publishing
Release Date: 2019-07-26
Reviews current research on the nutraceutical properties as well as allergen and other safety issues relating to tree nuts Assesses advances in breeding, cultivation, integrated disease and pest management to improve yields and sustainability Summarises key research on the main tree nuts, from walnuts and almonds to hazelnuts, chestnuts and pistachios