Volume application rate adapted to the canopy size in greenhouse tomato crops

Julián Sánchez-Hermosilla,Víctor J Rincón,José Pérez-Alonso,Francisco Páez

doi:10.1590/s0103-90162013000600003

Abstract

The application rate of plant-protection products is indicated as a concentration or amount of product per area. Greenhouse crops grow swiftly, and an application rate based on a fixed amount of product per hectare can result either in large losses and overdoses when the plants are small or to be insufficient when the plants are fully developed. To solve these problems, the application rates of plant-protection products need to be adapted to the plant mass present in the greenhouse when the spray is applied. Two models were developed to estimate the leaf area based on easily measured geometric data of the vegetation in a greenhouse tomato crop. The model based on the PRV (Plant Row Volume) had that best results. The calculation of the volume application rate from the PRV has resulted in a reduction of more than 30 % of the quantity of plant protection product sprayed, without decreasing yield. The PRV of a greenhouse tomato (Lycopersicon esculentum Mill.) is an easily measured parameter that enables the estimation of the leaf area index and the use of application strategies adapted to the changes in the plant canopy, saving major amounts of plant protection product used, compared to the conventional system.

Highlights

Quantifying vegetation and its subsequent relation to the spray-application rate are the basis for techniques of crop adapted spraying (CAS) used by researchers (Sutton and Unrath, 1988; Giles et al, 1989; Rüegg et al, 1999; Gil et al, 2007; Pergher and Petris, 2008) for applying plant protection products in different crops
One method is the “Tree-Row Volume” (TRV) (Byers et al, 1971), whereby the application rate is determined by comparing the crop canopy volume per surface-area unit with the rate applied to a standard crop
This study describes a model to estimate the leaf area based on measured geometric data of the vegetation in a greenhouse tomato crop, such as the canopy height or the Plant Row Volume (PRV), and its use to calculate the volume application rate of plant protection product from the average foliar deposit

Summary

Introduction

Quantifying vegetation and its subsequent relation to the spray-application rate are the basis for techniques of crop adapted spraying (CAS) used by researchers (Sutton and Unrath, 1988; Giles et al, 1989; Rüegg et al, 1999; Gil et al, 2007; Pergher and Petris, 2008) for applying plant protection products in different crops. One method is the “Tree-Row Volume” (TRV) (Byers et al, 1971), whereby the application rate is determined by comparing the crop canopy volume per surface-area unit with the rate applied to a standard crop This method specifies the application rates in a more methodical way and has rendered good results in orchards (Sutton and Unrath, 1988; Rüegg et al, 1999; Gil et al, 2007; Siegfried et al, 2007). For high crops the application rate is to be expressed in terms of the “leaf wall area” (LWA) (Koch, 2007) Another way of establishing the application rate as a quantity of spray product per unit of leaf surface area is from the measurement of the LAI (Leaf Area Index). This study describes a model to estimate the leaf area based on measured geometric data of the vegetation in a greenhouse tomato crop, such as the canopy height or the Plant Row Volume (PRV), and its use to calculate the volume application rate of plant protection product from the average foliar deposit

Materials and Methods

Results and Discussion

Conclusions