This news article was originally written in Spanish. It has been automatically translated for your convenience. Reasonable efforts have been made to provide an accurate translation, however, no automated translation is perfect nor is it intended to replace a human translator. The original article in Spanish can be viewed at Teledetección y programación del riego en los viñedos

The investigations have allowed the design of a program for the agriculturalist, from the cual is possible to see the state hídrico of each sector of irrigation of his viñedos

Teledetection and programming of the irrigation in the viñedos

Irta 15/02/2013

To realise a programming of the efficient irrigation is necessary to use indicators that give us information on the state hídrico of the plants. The indicator commonly more used to experimental level is the potential hídrico of the leaf or of the cut (Ψ). This parameter indicates us the degree of 'are' that has a plant. However, it is an indicator engorroso in his measurement, as it requires realise individual measurements in the leaves of the plants of a crop.

Researchers of the Irta have showed in vineyard that is possible to program the irrigation in a crop realising measures of the potential hídrico weekly. Since we know the value of the potential hídrico of leaf measured and also which would have to be his optimum value in each moment, will be able to program the irrigation in function of his state hídrico.

Experimentally this is possible. However, carry to the reality of a crop the necessary measurements is flour of another costal, as for this is necessary to have of a team of measure (camera of pressesure), realise measures weekly and program in function of the result, taking the timely decisions costing us of the data obtained. Besides, the diversity of existent floors in a viñedo (more or less deep), comports different capacities of retention of available water to be absorbed by the roots of the cepas. This situation translates in zones of distinct variability regarding his needs of irrigation, by what does not serve to realise the measurements in a single place of the viñedo.

The options go through to realise the measurements in several places of the viñedo dividing it in subzonas with the same characteristics or levels of stress of the vineyards for, like this, realise a measurement in each one of these subzonas (between 8 and 10 measurements/viñedo, as they do some viñedos Californian at present).

It exists some methodology that make possible to estimate the needs of water in big extensions without having to do so many measurements in the crop? As yes it exists, and it bases in the use of the teledetection.

The teledetection

The plants, like living beings that are, transpiran. When a plant goes in in deficit hídrico (that is to say, loses more water of which goes in him), the stomas go closing, what does to diminish his transpiration like formula to defend of the loss of water, as well as his capacity to realise the photosynthesis. To consequence of this the temperature of the plant increases and generates a thermal sensors image of heat in proportion to his deficit hídrico. The difference of temperature between the existent to level of the leaf and the one of the air can arrive until the 8 °C in plants very estresadas and between 2-3 °C in the plants very hidratadas.

This is the principle in which it bases the teledetection, and for the measurement of the temperature of the leaf in big extensions of viñedos is necessary the utilisation of thermal sensors cameras of high installed resolution in avionetas (tripuladas or no). The use of cameras of high resolution is necessary to avoid the effect of the floor in the thermal sensors images generated.

The Institute of Sustainable Agriculture (IAS-CSIC) of Córdoba, has worked in this sense, using avionetas teledirigidas no tripuladas. Recently, in the Irta, has split of the technology developed in the IAS-CSIC and, jointly, both institutes have developed the system for avionetas tripuladas, allowing work to the same height of flight (150 m of altitude) and obtaining the same resolution of images, in addition to having of a greater autonomy of flight and, consistently, cover some greater extensions in the acquisition of thermal sensors images regarding the avionetas no tripuladas.

In base to this methodology has been possible to generate maps of the state hídrico of the viñedos. Using the two systems of acquisition of thermal sensors images (tripulados or no), the researchers of the Irta saw that it existed a correlation between the temperature of the leaf and the state hídrico of the cepas measured from the potential hídrico of leaf. The relations obtained in distinct moments of the year measuring the potential hídrico at the same time that they obtained the thermal sensors images.

In base to the relations obtained, for the first time, programmed the irrigation of a viñedo of 15 hectares in base to thermal sensors images of high resolution and showed the possibility to irrigate individually each sector in function of his state hídrico. Like this, the quantities of water contributed in the distinct sectors miscellaneous significantly, since the needs hídricas were distinct.

Finally, the investigations have allowed the design of a program for the agriculturalist, from the cual is possible to see the state hídrico of each sector of irrigation of his viñedos, being able to like this know with precision the quantity of water to supply weekly in each sector of irrigation.

When measure and how much can cost?

The experiences realised by the Irta and the IAS-CSIC show that the best hour of the day to detect the state hídrico of the plants by means of thermal sensors images is around the 14:00 h (12:00 solar hour). Besides, it studied the frequency of acquisition of necessary thermal sensors images to program the irrigation, realising flights once a week or each 15 days. The results showed that the harvest and the quality of the wine did not see affected when it programmed the irrigation from the images obtained each 15 days. Only if it adopted a strategy of irrigation deficitario severe would advise purchase images weekly.

Regarding the optimum moment to start with to realise flights, seem to be that, in the case of viñedos, the start of the flights would be from 15 June, since before this date there is little vegetation and the thermal sensors images are not precise.

With repecto to the cost of the flights the figure is variable in function, for example, of a greater or lower vicinity to an airfield, of the total surface to sobrevolar, etc. However, the cost could oscillate between the 15 and the 45 euros/has and flight. Economic quantity that compensates with grow by the big saving of water that this system allows.

Information elaborated from the report that the researcher of the IRTA Joaquim Bellver realised the past 17 January in the day on 'Different strategies of irrigation in vineyard' and that carried by title 'Use of the teledetection like tool for the programming of irrigation in vineyard'.