**Sustentable Use of the Wetting Agents in Protected Horticulture**

Carlos Guillén and Miguel Urrestarazu *Universidad of Almería, Spain* 

#### **1. Introduction**

The wetting agents in agriculture are materials that are classified within a larger group identified as adjunvants (Cahn and Lynn, 2000; Hazen, 2000; Kosswig, 2000; Thacker, 2003; Young, 2003; Lynn y Bory, 2005). According to their chemical nature, adjuvants are grouped into four families: surfactants, oils, inorganic salts and non-traditional adjuvants (figure 1). Nowdays some of the wetting agentes can be considered inside of called Green Chemistry (Carrasco and Urrestarazu, 2010).

Fig. 1. Classification of adjunvants according to their chemical nature and function

Sustentable Use of the Wetting Agents in Protected Horticulture 149

AV: air volume, WHC: water holding capacity, EAW: easily available water

and horticultural cultures on substrate

Table 1. Summary of research on the effect of application of wetting agent in ornamental

#### **1.1 Surfactant**

A common mistake is the use of adjuvantand surfactant terms inter changeably, which arises from the same discrepancy between producers(Young, 2003). The tru this that surfactantisa chemical family of adjuvants that improve emulsion, dispersion, foam, wet or other properties of a fluid to alter the characteristics of surface or interface and surface tension (Hazen, 2000, Thacker, 2003; Young, 2003). The termsurfactantis derived from the contraction of three words Surface Active Agents (Thacker, 2003; Rosen, 2004, RAE, 2001).

Global consumption of surfactants in agriculture is 250 thousand tons per year, 180 thousand of which are incorporated in the formulation of fitosanitariosy 70 000 tonnes are used as tank mix adjuvants (Thacker, 2003). Besides agriculture surfactants are used in various products such as motor oils for cars, pharmaceuticals, in detergents, in materials used in oil exploration and floating agents in mining, in recent decades has extended its application to electronic printing, magnetic recording, biotechnology and viral research (Rosen, 2004).

Surfactant are molecules of low to middle rate molecular weight, it is amphipathic nature, it is containing a hydrophobic or lipophilic part (carbon chain) and a hydrophilic or lipophobic (Malmnsten, 2002, Rosen, 2004; Tadros, 2005).

The hydrophobic groups are alkyl and alkylaryl groups mostly hydrocarbon, hydrophilic groups can be ionic or nonionic (Kosswig, 2000). According to this type ionic surfactants may be anionic, cationic, amphoteric and nonionic surfactants (Figure 2). In an anionic surfactant hydrophilic segment of the molecule forms an anion when dissolved in water. The opposite occurs in the cationic surfactant in which the active portion of the molecule in the hydrophilic segment is only a cation when dissolved in water. An amphoteric surfactant is capable of forming anions in aqueous solution depending on pH or cations. The nonionic surfactant is a surface active agent without ionic polar group is not ionized in aqueous solution (American Society for Testing and Materials E 1519, 1999, Cahn and Lynn, 2000; Kosswig, 2000; Malmnsten, 2002; Rosen, 2004, Young, 2003, Lynn and Bory, 2005).

Fig. 2. Diagram of a humectant molecules


AV: air volume, WHC: water holding capacity, EAW: easily available water

Table 1. Summary of research on the effect of application of wetting agent in ornamental and horticultural cultures on substrate

148 Horticulture

A common mistake is the use of adjuvantand surfactant terms inter changeably, which arises from the same discrepancy between producers(Young, 2003). The tru this that surfactantisa chemical family of adjuvants that improve emulsion, dispersion, foam, wet or other properties of a fluid to alter the characteristics of surface or interface and surface tension (Hazen, 2000, Thacker, 2003; Young, 2003). The termsurfactantis derived from the contraction of three words Surface Active Agents (Thacker, 2003; Rosen, 2004, RAE, 2001). Global consumption of surfactants in agriculture is 250 thousand tons per year, 180 thousand of which are incorporated in the formulation of fitosanitariosy 70 000 tonnes are used as tank mix adjuvants (Thacker, 2003). Besides agriculture surfactants are used in various products such as motor oils for cars, pharmaceuticals, in detergents, in materials used in oil exploration and floating agents in mining, in recent decades has extended its application to electronic

Surfactant are molecules of low to middle rate molecular weight, it is amphipathic nature, it is containing a hydrophobic or lipophilic part (carbon chain) and a hydrophilic or

The hydrophobic groups are alkyl and alkylaryl groups mostly hydrocarbon, hydrophilic groups can be ionic or nonionic (Kosswig, 2000). According to this type ionic surfactants may be anionic, cationic, amphoteric and nonionic surfactants (Figure 2). In an anionic surfactant hydrophilic segment of the molecule forms an anion when dissolved in water. The opposite occurs in the cationic surfactant in which the active portion of the molecule in the hydrophilic segment is only a cation when dissolved in water. An amphoteric surfactant is capable of forming anions in aqueous solution depending on pH or cations. The nonionic surfactant is a surface active agent without ionic polar group is not ionized in aqueous solution (American Society for Testing and Materials E 1519, 1999, Cahn and Lynn, 2000;

hydrophilic heads hydrophobic tails

Kosswig, 2000; Malmnsten, 2002; Rosen, 2004, Young, 2003, Lynn and Bory, 2005).

**+**

**o**

**-** 

**-** 

printing, magnetic recording, biotechnology and viral research (Rosen, 2004).

lipophobic (Malmnsten, 2002, Rosen, 2004; Tadros, 2005).

**+**

**-** 

**+**

Fig. 2. Diagram of a humectant molecules

*Anionic*

*Cationic*

*No ionic*

*Anfoteric*

**1.1 Surfactant** 

Sustentable Use of the Wetting Agents in Protected Horticulture 151

the fertilizer applied in the soil solution increases the mineralization of organic matter, wet consistency, improves water infiltration, reduces the flooded surface, reduces evaporation

In trade, de Linan (2006), we found in the group of adjuvants to 30 products, among which

Surfactant nonionic

Surfactant nonionic

Surfactant nonionic

non-ionic wetting

With wetting power

With wetting power

With wetting power

power

power

tension

power

Material Coadjuvant kind

1 Alkyl ethoxylated fatty amines 73.5% w/v. SL Surfactant nonionic

4 Alquilpoliglicol 20% w/v. EC Nonionic adjuvant

5 Alquilpoliglicol 44% + 1.5% sodium dioctyl w/v. SL Surfactant nonionic

6 Sodium Alquiletersulfato 29% w/v. SL Surfactant nonionic

8 Montan wax 20% w/v. EW Adherent-adjuvant and

9 ammonium dodecylbenzenesulfonate 20% w/v. SL Adjuvant anionic wetting

10 Ammonium dodecylbenzenesulfonate 20% w/v. EC Adjuvant anionic wetting

12 Methyl oleate / methyl palmitate 34.5% w/v. EC It reduces the surface

13 Surfactant nonionic 20% p/v. SL Surfactant nonionic

14 EterNonilfenolpolietilenglicolr 20% p/v. SL Surfactant nonionic

17 Copper phthalate 66.5% w/v. EC Adjuvant anionic wetting

EC: Emulsifiable concentrate, EW: Emulsion oil-water; SL: soluble concentrate, p/v: weight/volume

and increases the efficiency of water use in farming.

2 Alkyl ethoxylated fatty amine / propoxylated 48.7%

7 Ethylene Alquilfenilhidroxipolioxi + 10.1% synthetic

3 Alquil aminas grasas etoxiladas/propoxiladas 92% p/v.

are 17 active substances to wetting (Table 2).

w/v. SL

latex 45.45% w/v. EC

30% w/v. SL

Source: De Liñán (2006)

of fatty acids a dozen

11 Sodium dodecylbenzenesulfonate 5% +

nonilfeniloxietilenatosulfonado 2% w/v. SL

15 Eter Nonilfenolpolietilenglicol 30% + inorganic acid

16 Copper phthalate, are grouped a series of copper salts

Table 2. Wetting adjuvant for agricultural use in Spain

EC

The nonionic surfactants are chemically less active, but also less phytotoxic (Powell, 1986; Bures, 1997; Reinikainen and Herranen, 1997;) and less irritating than anionic and cationic (Malmnsten, 2002). They can with stand hard water and soluble in water and organic solvents, but can be sensitive to high temperatures (Rosen, 2004). Besides its critical concentration of micelle formation is twice lower than the anionic surfactants (Tadros, 2005). These nonionic surfactants are excellent wetting at very low concentrations (Thacker, 2003). They are the most dominant adjuvants of surfactants commercially available for the application of herbicides, they are less toxic to mammals (Young, 2003).

#### **1.2 Wetting agent**

Wetting agent is a substance used to reduce surface tension (Figure 3) and lead to better contact of a solution or suspension with a surface (WSSA Herbicide Handbook, 1994). Generally wetting agentis a surfactant, whose effectiveness is measured by the increase of spread of a liquid on a surface or the contact angle of liquid with the surface (Shurtleff and Averre, 1998).

Fig. 3. Contact angle and contact area for a drop water with and without a wetting agent on a hydrophobic surface

The wetting agents have been successfully used to improve the uniformity of wetting, improve relationships air: water of organic substrates and to improve nutrient availability to plants, without altering the physical characteristics of the substrate (Powell, 1986; Baht et al., 1992, Cid et al., 1992, Blodgett et al., 1993).

Crabtree and Gilkes (1999) indicate that the wetting agent also apply water repellent soils and have several benefits for the soil-plant system because it improves the soil wet releases

The nonionic surfactants are chemically less active, but also less phytotoxic (Powell, 1986; Bures, 1997; Reinikainen and Herranen, 1997;) and less irritating than anionic and cationic (Malmnsten, 2002). They can with stand hard water and soluble in water and organic solvents, but can be sensitive to high temperatures (Rosen, 2004). Besides its critical concentration of micelle formation is twice lower than the anionic surfactants (Tadros, 2005). These nonionic surfactants are excellent wetting at very low concentrations (Thacker, 2003). They are the most dominant adjuvants of surfactants commercially available for the

Wetting agent is a substance used to reduce surface tension (Figure 3) and lead to better contact of a solution or suspension with a surface (WSSA Herbicide Handbook, 1994). Generally wetting agentis a surfactant, whose effectiveness is measured by the increase of spread of a liquid on a surface or the contact angle of liquid with the surface (Shurtleff and

**Without wetting agent With wetting agent** 

Fig. 3. Contact angle and contact area for a drop water with and without a wetting agent on

contact area

The wetting agents have been successfully used to improve the uniformity of wetting, improve relationships air: water of organic substrates and to improve nutrient availability to plants, without altering the physical characteristics of the substrate (Powell, 1986; Baht et al.,

Crabtree and Gilkes (1999) indicate that the wetting agent also apply water repellent soils and have several benefits for the soil-plant system because it improves the soil wet releases

application of herbicides, they are less toxic to mammals (Young, 2003).

**1.2 Wetting agent** 

Averre, 1998).

a hydrophobic surface

Hydrophobic surface

Contact angle

1992, Cid et al., 1992, Blodgett et al., 1993).

the fertilizer applied in the soil solution increases the mineralization of organic matter, wet consistency, improves water infiltration, reduces the flooded surface, reduces evaporation and increases the efficiency of water use in farming.

In trade, de Linan (2006), we found in the group of adjuvants to 30 products, among which are 17 active substances to wetting (Table 2).


Source: De Liñán (2006)

EC: Emulsifiable concentrate, EW: Emulsion oil-water; SL: soluble concentrate, p/v: weight/volume

Table 2. Wetting adjuvant for agricultural use in Spain

Sustentable Use of the Wetting Agents in Protected Horticulture 153

New coir fiber

Humectant (mg L

New Rockwool


LSD0.05

Fig. 5. The square of Humectant delete de red line behind, this must be like de red line as

Humectant (mg L


LSD0.05

below

Easily Avilable Water

Easily Avilable Water

### **2. Application of wetting agent in crop production**

#### **2.1 Assessment of toxicity**

It is important before using a new wetting agent, evaluate their toxicity to plants (Handreck and Black, 1994). The bioassays used to assess the phytotoxicity of substrates (Zucconi et al., 1981, Ortega et al., 1996) were used to evaluate the toxicity of some products used in soilless culture (Urrestarazu and Mazuela, 2005). Urrestarazu et al. (2006) reported an adequate concentration of a surfactant with bioassays of tomato and cress.

#### **2.2 Improving substrates**

#### **2.2.1 Wettability and water holding of growing media**

The wettability of growing media (figure 4) is an important characteristic that could be limiting due to alternations of humectation and desiccation or drying accidental events that could modify considerably and reversibly or not the properties of the substrate during growing crops (Da Silva et al., 1993; Otten et al., 1999, Chambers and Urrestarazu, 2004, Lemaire et al., 2005).

Reduction of wettability contributes to vertical flow and goes against horizontal flow and water retention in growing media (Handreck and Black, 1994; Beeson and Haydu, 1995; Dekker and Ritsema, 1994, 1996 and 2000; Salas and Urrestarazu, 2004; Dekker et al., 2005).

Greater water retention capacity at low matrix potential is very important for optimal plant growth (Plaut et al., 1973, Plaut and Zieslin, 1974, Feigin et al., 1988; Raviv et al., 2002, Sahin et al., 2002, Chambers and Urrea, 2004). There have been several experiments to correlate the growth of plants with water retention and air capacity of the substrates and these has been found that the plant qrowth is highly correlated with water retention and low air capacity is associated with a low crop growth (Allaire et al., 1996). These problems of hydrophobia and low holding water in substrates can be overcome by application of wetting agent.

Fig. 4. Water repellency of dry organic substates

It has been shown that surfactants facilitate the movement of water into and through the substrate, control the infiltration of water distribution and drainage, because it affects reserves of moisture, nutrient availability and aeration, with an optimal concentration of these surfactants improve rewetting potential of substrates and reduce root stress related problems, allowing greater control of plant growth (Powell, 1986, Bhat et al., 1990).

It is important before using a new wetting agent, evaluate their toxicity to plants (Handreck and Black, 1994). The bioassays used to assess the phytotoxicity of substrates (Zucconi et al., 1981, Ortega et al., 1996) were used to evaluate the toxicity of some products used in soilless culture (Urrestarazu and Mazuela, 2005). Urrestarazu et al. (2006) reported an adequate

The wettability of growing media (figure 4) is an important characteristic that could be limiting due to alternations of humectation and desiccation or drying accidental events that could modify considerably and reversibly or not the properties of the substrate during growing crops (Da Silva et al., 1993; Otten et al., 1999, Chambers and Urrestarazu, 2004,

Reduction of wettability contributes to vertical flow and goes against horizontal flow and water retention in growing media (Handreck and Black, 1994; Beeson and Haydu, 1995; Dekker and Ritsema, 1994, 1996 and 2000; Salas and Urrestarazu, 2004; Dekker et al., 2005). Greater water retention capacity at low matrix potential is very important for optimal plant growth (Plaut et al., 1973, Plaut and Zieslin, 1974, Feigin et al., 1988; Raviv et al., 2002, Sahin et al., 2002, Chambers and Urrea, 2004). There have been several experiments to correlate the growth of plants with water retention and air capacity of the substrates and these has been found that the plant qrowth is highly correlated with water retention and low air capacity is associated with a low crop growth (Allaire et al., 1996). These problems of hydrophobia and low holding water in substrates can be overcome by

It has been shown that surfactants facilitate the movement of water into and through the substrate, control the infiltration of water distribution and drainage, because it affects reserves of moisture, nutrient availability and aeration, with an optimal concentration of these surfactants improve rewetting potential of substrates and reduce root stress related

new peat new coir waste used coir waste

problems, allowing greater control of plant growth (Powell, 1986, Bhat et al., 1990).

**2. Application of wetting agent in crop production** 

concentration of a surfactant with bioassays of tomato and cress.

**2.2.1 Wettability and water holding of growing media** 

**2.1 Assessment of toxicity** 

**2.2 Improving substrates**

Lemaire et al., 2005).

application of wetting agent.

Fig. 4. Water repellency of dry organic substates

Fig. 5. The square of Humectant delete de red line behind, this must be like de red line as below

Sustentable Use of the Wetting Agents in Protected Horticulture 155

**\***

Fig. 6. Significant increases in the incorporation of potassium in melon cultivation of coconut fiber used. T0 = Control, T1 with humectant. FCN: New coir fiber, FCU: Used fiber

**\***

FCN FCU LRN LRU

**\*\***

T0 T1

Fig. 7. Significant reduction in the emission of nutrients in a melon crop in reused coco fiber as a result of a wetting agent applied in fertigation. T0 = Control, T1 with humectant. FCN: New coir fiber, FCU: Used fiber coir. LRN: New rockwool, FRU: Used rockwool.

FCN FCU LRN LRU

T0 T1

coir. LRN: New rockwool, FRU: Used rockwool.

0

400

**NO3**

\**P*≤ 0,01

**- (mmol**

**c m**

**-2)**

800

1200

1600

0

200

\*P≤ 0,01; \*\*P≤ 0,05

400

**K+ (mmol**

**c m**

**-2)**

600

800

1000

1200

#### **2.2.2 Improving physical properties of substrates**

There is a considerable amount of articles about application of surfactants in ornamental and horticultural crops on different substrates. Table1 shows some research on application of wetting agent on crop son substrate. Surfactants applied to organic growing media such as peat and pine fiber can improve absorption of water (wettability) of substrate (Handreck, 1992, Elliot, 1992; Blodgett et al., 1993, Riviere et al., 1996; Michelet al., 1997; Reinikainen and Herranen, 1997), also can increase air capacity, raising the drain (Wilson, 1985; Powell, 1986; Milksetal, 1989; Reinikainen and Herranen, 1997) or can improve the water holding capacity (Airhart et al., 1980; Handreck, 1992; Handreck and Black,1994, Elliot, 1992; Bilderback and Lorscheider, 1997, Cid et al., 1998), increasing the water held inmicropores. May also increase the water content readily available, without increasing the capacity of container (Blodgett et al., 1993) or increase the total available water content with increased water holding capacity (Riviere et al., 1996.). Urrestarazu et al (2008) reported that the effect of wetting agent added through fertigation is directly dependant on the substrate type evaluated and it can reduce the available water and increase the easily avilable water and total water holding capacity.

#### **2.3 Increasing efficiency in ornamentals**

Also can improve growth and production of ornamental species if applied at rates not phytotoxic (Bhat et al., 1990, Cid et al., 1993; Bilderback and Lorscheider, 1997, Cid et al., 1998), even allow to increase the availability and absorption of nutrients, especially calcium absorption (Bath et al., 1990, Cid et al., 1998). And apparently the application in fertigation could be the best method of application, less phytotoxic than when initially mixed with the substrate (Bhat et al., 1990).

#### **2.4 Increasing efficiency in vegetables**

In application by fertigation, the surfactant increased nutrients uptake, especially potassium (*P* = 0.08), nitrate (*P* = 0.15) and phosphate (*P* = 0.25), in melon crop on coir waste. Also it was observed a decrease in the percentage of drainage and reducing the emission of nitrates, phosphates, potassium and calcium (*P* ≤ 0.2) in melon crop, showing its usefulness in lower environmental pollution (Guillen and Urrestarazu, 2006).

This observed in coir mojantesmejoran shows that the properties of the substrate water quality by reducing the hydrophobic effect acquired especially for use. But we have discussed in the previous section that this property is related to the concentration of mojanteque used, hence the application by fertigation should be adjusted to find the desired effect. In short, the goal is to improve efficiency, since the increased incorporation counterpart brings in reducing polluting emissions.

In tomato trial, the first year was observed higher yield in crop on reused coir waste and greater efficiency in water use (*P* < 0.10), proving useful for improving the use of water when a wetting agent is applied by fertigation. Also was observed a greater efficiency in the second year in reused coir waste (*P* = 0.07) and reused rockwool (*P* = 0.03) (Guillen and Urrestarazu, 2006).

It is inferred that the wetting by fertigation is a useful tool to adjust the water relations of sutratos used, which is reflected in higher production volume of water consumed.

There is a considerable amount of articles about application of surfactants in ornamental and horticultural crops on different substrates. Table1 shows some research on application of wetting agent on crop son substrate. Surfactants applied to organic growing media such as peat and pine fiber can improve absorption of water (wettability) of substrate (Handreck, 1992, Elliot, 1992; Blodgett et al., 1993, Riviere et al., 1996; Michelet al., 1997; Reinikainen and Herranen, 1997), also can increase air capacity, raising the drain (Wilson, 1985; Powell, 1986; Milksetal, 1989; Reinikainen and Herranen, 1997) or can improve the water holding capacity (Airhart et al., 1980; Handreck, 1992; Handreck and Black,1994, Elliot, 1992; Bilderback and Lorscheider, 1997, Cid et al., 1998), increasing the water held inmicropores. May also increase the water content readily available, without increasing the capacity of container (Blodgett et al., 1993) or increase the total available water content with increased water holding capacity (Riviere et al., 1996.). Urrestarazu et al (2008) reported that the effect of wetting agent added through fertigation is directly dependant on the substrate type evaluated and it can reduce the

available water and increase the easily avilable water and total water holding capacity.

Also can improve growth and production of ornamental species if applied at rates not phytotoxic (Bhat et al., 1990, Cid et al., 1993; Bilderback and Lorscheider, 1997, Cid et al., 1998), even allow to increase the availability and absorption of nutrients, especially calcium absorption (Bath et al., 1990, Cid et al., 1998). And apparently the application in fertigation could be the best method of application, less phytotoxic than when initially mixed with the

In application by fertigation, the surfactant increased nutrients uptake, especially potassium (*P* = 0.08), nitrate (*P* = 0.15) and phosphate (*P* = 0.25), in melon crop on coir waste. Also it was observed a decrease in the percentage of drainage and reducing the emission of nitrates, phosphates, potassium and calcium (*P* ≤ 0.2) in melon crop, showing its usefulness in lower

This observed in coir mojantesmejoran shows that the properties of the substrate water quality by reducing the hydrophobic effect acquired especially for use. But we have discussed in the previous section that this property is related to the concentration of mojanteque used, hence the application by fertigation should be adjusted to find the desired effect. In short, the goal is to improve efficiency, since the increased incorporation

In tomato trial, the first year was observed higher yield in crop on reused coir waste and greater efficiency in water use (*P* < 0.10), proving useful for improving the use of water when a wetting agent is applied by fertigation. Also was observed a greater efficiency in the second year in reused coir waste (*P* = 0.07) and reused rockwool (*P* = 0.03) (Guillen and

It is inferred that the wetting by fertigation is a useful tool to adjust the water relations of

sutratos used, which is reflected in higher production volume of water consumed.

**2.2.2 Improving physical properties of substrates** 

**2.3 Increasing efficiency in ornamentals** 

**2.4 Increasing efficiency in vegetables** 

environmental pollution (Guillen and Urrestarazu, 2006).

counterpart brings in reducing polluting emissions.

substrate (Bhat et al., 1990).

Urrestarazu, 2006).

Fig. 6. Significant increases in the incorporation of potassium in melon cultivation of coconut fiber used. T0 = Control, T1 with humectant. FCN: New coir fiber, FCU: Used fiber coir. LRN: New rockwool, FRU: Used rockwool.

Fig. 7. Significant reduction in the emission of nutrients in a melon crop in reused coco fiber as a result of a wetting agent applied in fertigation. T0 = Control, T1 with humectant. FCN: New coir fiber, FCU: Used fiber coir. LRN: New rockwool, FRU: Used rockwool.

Sustentable Use of the Wetting Agents in Protected Horticulture 157

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Bhat, N.R.; Prince, T.L.; Tayama, H.K. & Carver, S.A. (1992). Rooted cutting establishment in

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Blodgett, A.M.; Beattie, D.J.; White, J.W. & Elliot, G.C. (1993). Hydrophilic polymers and

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242.

635.

126.

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342 pg. ISBN 84-87480-75-6

Sciences*,* 11(5), 1999-2009.

Horticulturae 342, 307-311.

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Fig. 8. Efficient water use in different substrates with and without wetting. T0= Testigo, T1 with humectant. FCN: New coir fiber, FCU: Used fiber coir. LRN: New rockwool, FRU: Used rockwool.

#### **3. Acknowledgements**

The authors acknowledge the collaboration of Ministry of Science and Innovation Spanish through the project FEDER AGL2010-18391.

#### **4. References**

156 Horticulture

0,00 0,02 0,04 0,06 0,08 0,10 0,12

**Eficiencia de uso de agua**

T0 T1

1. FCN 2. FCU

*P*= 0,0234

**kg L-1 consumidos**

Fig. 8. Efficient water use in different substrates with and without wetting. T0= Testigo, T1 with humectant. FCN: New coir fiber, FCU: Used fiber coir. LRN: New rockwool, FRU:

The authors acknowledge the collaboration of Ministry of Science and Innovation Spanish

Used rockwool.

0,00 0,01 0,02 0,03 0,04 0,05 0,06 0,07

**Eficiencia de uso de agua**

1. FCN 2. FCU

*P*= 0,0554

**kg L-1 aportados**

**3. Acknowledgements** 

through the project FEDER AGL2010-18391.


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**Postharvest Technologies of** 

*Autonomous University of Nuevo Leon, Escobedo, N.L., 2Department of Bioresource Engineering, Macdonald Campus,* 

*McGill University, Ste-Anne-de-Bellevue, Québec, 3Kyushu University, Laboratory of Agricultural Ecology,* 

> *1Mexico 2Canada 3Japan*

Alejandro Isabel Luna-Maldonado1, Clement Vigneault2 and Kei Nakaji3

The actual processing of fresh horticultural produce and the reducing labor force have begun to force the development of robots that are capable of dealing with the variations inherent in the produce being handled, stored and transported. All around the world, there is increasing interest in the use of robots to replace the drastic decreasing number of farmers due to the lower birth rate and the increasing average age of the remaining farmers (Kitamura *et al., 2004* & Wang, 2009). In the USA, the supply of workers available for hand harvesting is decreasing steadily and true shortages are occurring. Without enough workers when needed for a few weeks each year, a large amount of hand harvested crops will be lost. Fruit and vegetable crops need new productive harvesting technologies (Sarig *et al.,*

In general, with horticulture applications, the variations of fresh produce in size and color as well as in the internal structure and defects such as over-ripeness and bruising damage are considered the main barriers to the extension of robotics. Robots have to cope with produce delivered with random orientation and placement, and with environmental issues such as a wide range of humidity and temperature resulting in condensation problems on electronic circuit or dew on sensors of all kinds. It requires manipulator mechanisms, controls and end-manipulators to be designed to interact with the surrounding environment, sensing techniques, mobility, and work cell development. Typical applications where imaging and electro-sensing processes can be used to guide robots include sensing general fruit quality (ElMasry *et al.* 2009; Li *et al*., 2006 & Lino *et al*., 2008), measuring internal quality parameters (Chen, 2008 & Li *et al.,* 2009), or detecting mechanical (ElMasry *et al.,* 2008) or physiological (ElMasry *et al.,* 2009) damage, for either grading the produce accordingly or involving automatic trimming robots to remove the defect. In other words, processed items are picked

**1. Introduction** 

2010)

*1Department of Agricultural and Food Engineering, Faculty of Agriculture,* 

*Division of Agricultural Ecology, Department of Plant Resources, Fukuoka,* 

**Fresh Horticulture Produce** 

Zucconi, F.; Forte, M. & De Bertoldo, M. (1981). Biological evaluation of compost maturity.BioCycle (July/August), 27-29. **9** 
