Effects of Linseed Oil Spray on some Physiological Traits of Durum Wheat and Barley under Glasshouse Water Deficit Stress

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1 Effects of Linseed Oil Spray on some Physiological Traits of Durum Wheat and Barley under Glasshouse Water Deficit Stress Fethi Ouerghi, Office de Développement Sylvo-Pastoral du Nord-Ouest, Route de Tunis, 9000, Béja, Tunisia, Gaïth Bouzaien, Ali Albouchi, Institut National de la Recherche en Génie Rural, Eaux et Forêts, Rue Hédi Karray, 2080 Ariana, Tunisia, Moncef Ben-Hammouda, Hatem Cheikh M hamed, Souad Aloui-Rezgui, and Bouzid Nasraoui, Ecole Supérieure d Agriculture du Kef, 7119, Le Kef, Tunisia ABSTRACT Ouerghi, F., Bouzaien, G., Albouchi, A., Ben-Hammouda, M., Cheikh M hamed, H., Aloui- Rezgui, S., and Nasraoui, B Effects of linseed oil spray on some physiological traits of durum wheat and barley under glasshouse water deficit stress. Tunisian Journal of Plant Protection 5: 1-8. Antitranspirant film reduces mechanically not only stomata and cuticle transpiration but also gas exchanges. As most of the water absorbed by plants is lost by transpiration, reducing plant transpiration could conserve absorbed water and minimize plant stress. The goal of this study is to investigate the conditions of antitranspirant use without affecting gas exchanges on leaves. Experiments were carried out in a glasshouse to study the effects of an antitranspirant linseed oil on some physiological traits of durum wheat and barley. The two cereals were grown under water deficit stress and the antitranspirant was sprayed two times at 5, 7 and 10%, at the tillering and the stem elongation stages. Measurements of foliar water potential and photosynthetic rate indicate that the antitranspirant treatment improved the plant water status while there was no significant reduction in the photosynthetic activity. The antitranspirant sprayed at two concentrations (7 and 10%) under water deficit allowed plant to save more foliar water content in comparison to control. Keywords: Antitranspirant, barley, durum wheat, linseed oil, plant physiology When sprayed on plants, antitranspirants are known to form films that reduce stomata and cuticle transpiration and also some gas exchanges. Reduction in transpiration and photosynthetic activity may be accompanied by a reduced yield (2). Corresponding author: Bouzid Nasraoui nasraoui.bouzid@iresa.agrinet.tn Accepted for publication 26 Mai 2010 Some of other antitranspirants reduce water loss by leaves without greatly affecting photosynthetic activities (6). Antitranspirants are frequently criticized for reducing photosynthetic production, but it has been shown that when water is the limiting factor, this does not seem to be the case (4). Spraying of antitranspirants on plants under water deficit may allow them to retain a higher amount of water, improving thus their resistance to this stress. Moreover, the films formed on the leaf surface could prevent the physical contact between Tunisian Journal of Plant Protection 1 Vol. 5, No. 1, 2010

2 plants and foliar fungal pathogens, acting as physical barrier against their penetration into leaves (5). The aim of this work is to study the effect of an antitranspirant (linseed oil) on some physiological traits in durum wheat and barley grown under water deficit stress. MATERIALS AND METHODS Materials. To carry out this experiment, two cereal species were used: durum wheat variety Karim and barley variety Rihane. The antitranspirant used was a pure linseed oil. Trial conditions. Experiments were carried out in a glasshouse at 14h/10h light-dark photoperiod. Day and night temperatures were 25 and 16 C, respectively. Five seeds of each cereal species were sown in pots of 0.5 l containing a mix of substratum soil and sand (ratio 2:1). Pots were watered daily at maximal field capacity (FC) during a week and then arranged in four groups which received water to meet 25, 50, 75 and 100% of field capacity (FC) level. Antitranspirant spray. The antitranspirant was sprayed on leaves at the tillering and the stem elongation stages, using three concentrations 5, 7 and 10%. The control plants were sprayed with water. A routine weighting (every 2 days) was performed to restore the soil moisture at the right level of FC. For all treatments, the plant weight was neglected. Measured parameters. The physiological traits (leaf water potential and photosynthesis) were measured at the tillering and the stem elongation stages, 2 weeks after antitranspirant spraying. Foliar water potential was measured with a Scholander Room Pressure (Type Corvallis, PMS 1000, Oregon, USA) between 12:00 and 14:00 p.m., whereas gas exchanges were assessed at the same time using a LICOR 1600 LCA 4 portable photosynthesis system (Licor Inc. Lincoln, NE, USA). Statistical analysis. The experiment was run in a split-plot design with 2 factors (antitranspirant concentration as the main factor and water deficit as subfactor), 3 replications and 4 blocks. An analysis of variance was conducted and mean separation was carried out according to the least significant difference (LSD) test at P < RESULTS Foliar water potential at tillering stage. Durum wheat. At the tillering stage and under 25% FC, the antitranspirant treatments with linseed oil generally reduced foliar water potential compared to the control (Fig. 1); therefore allowing durum wheat plants to retain more water content. Barley. Except at 25% of FC, there were no significant differences in the foliar water potential of barley plants treatments with the antitranspirant at the tillering stage (Fig. 2). However, as the antitranspirant concentration increased, water potential became less negative which indicated a better plant water status and therefore less incidence of drought stress. Tunisian Journal of Plant Protection 2 Vol. 5, No. 1, 2010

3 Fig. 1. Effect of antitranspirant foliar treatments with linseed oil on the foliar water potential of durum wheat Karim at the tillering stage under water deficit stress in glasshouse. CW: control, durum wheat, WT5: durum wheat treated with linseed oil at 5%, WT7: durum wheat treated with linseed oil at 7%, BV10: durum wheat treated with linseed oil at 10%, Water regimes: 25, 50, 75 and 100% of field capacity. Bars affected with the same letter are not significantly different at P Fig. 2. Effect of antitranspirant foliar treatments with linseed oil on the foliar water potential of barley Rihane at the tillering stage under water deficit stress in glasshouse. CB: control, barley, CB5: barley treated with linseed oil at 5%, CB7: barley treated with linseed oil at 7%, CB10: barley treated with linseed oil at 10%, Water regimes: 25, 50, 75 and 100% of field capacity. Bars affected with the same letter are not significantly different at P Tunisian Journal of Plant Protection 3 Vol. 5, No. 1, 2010

4 Foliar water potential at stem depends on economic and social elongation stage. parameters as well as on the number of Durum wheat. Generally, a new leaves formed after treatment. significant increase in the water content of durum wheat leaves was observed at the stem elongation stage caused by the antitranspirant treatments, except under 50% FC (Fig. 3). Generally, antitranspirants could have efficiency up to one moth (7). They may allow a reduction in water transpiration without greatly affecting photosynthetic efficiency (3). To measure the real antitranspirant effect, comparison must be Barley. A significant increase was observed at the stem elongation stage in performed with regard to control plants under water deficit stress and not under the foliar water potential of barley leaves normal conditions. Besides, treated with the antitranspirant under 50% antitranspirants are usually FC, compared to the control. Under 25% FC water regime, just a trend was recorded showing lower foliar water potential in the control (Fig. 4). biodegradable, obtained at low price and stable at large intervals of temperature, humidity and light. The present physiological study aimed to investigate the effect of linseed Photosynthetic rate. Durum wheat. At both tillering and stem elongation stages (Fig. 5), no significant differences were noted in the photosynthetic rate of durum wheat oil spray on durum wheat and barley under water deficit stress. Obtained results are in agreement with those of Ben Naceur and Ben Salem (1) and show that linseed oil spray may reduce the leaf following the antitranspirant treatments as transpiration without significantly compared to the controls. affecting the photosynthetic rate. The recorded data show that antitranspirant Barley. With all treatments, no treatments increased foliar water potential differences were observed between and maintained acceptable photosynthetic control plants and those treated by linseed rate. Foliar water potential was oil at both tillering and stem elongation significantly increased indicating that stages (Fig. 6). Photosynthetic activity cereal plants have more efficiently seems to be generally not affected by the retained some of their foliar water antitranspirant treatment. content. More studies should be conducted to confirm the effectiveness of DISCUSSION The usefulness of antitranspirant films (from few days to few weeks) this antitranspirant and to try to improve its effect probably by adding surfactant adjuvant. RESUME Ouerghi F., Bouzaien G., Albouchi A., Ben-Hammouda M., Cheikh M hamed H., Aloui-Rezgui S. et Nasraoui B Effets de la pulvérisation de l huile de lin sur quelques caractéristiques physiologiques du blé dur et de l orge cultivés sous stress de déficit hydrique en serre vitrée. Tunisian Journal of Plant Protection 5: 1-8. Les antitranspirants du type film réduisent non seulement la transpiration végétale à travers les stomates et la cuticule mais aussi les échanges gazeux. Etant donné que la majorité de l eau absorbée Tunisian Journal of Plant Protection 4 Vol. 5, No. 1, 2010

5 Fig. 3. Effect of antitranspirant foliar treatments with linseed oil on the foliar water potential of durum wheat Karim at the stem elongation stage under water deficit stress in glasshouse. CW: control, durum wheat, WT5: durum wheat treated with linseed oil at 5%, WT7: durum wheat treated with linseed oil at 7%, WT10: durum wheat treated with linseed oil at 10%, Water regimes: 25, 50, 75 and 100% of field capacity. Bars affected with the same letter are not significantly different at P Fig. 4. Effect of antitranspirant foliar treatments with linseed oil on the foliar water potential of barley Rihane at the stem elongation stage under water deficit stress in glasshouse. CB: control barley, CB-5: barley treated with linseed oil at 5%, CB7: barley treated with linseed oil at 7%, CB10: barley treated with linseed oil at 10%, Water regimes: 25, 50, 75 and 100% of field capacity. Bars affected with the same letter are not significantly different at P Tunisian Journal of Plant Protection 5 Vol. 5, No. 1, 2010

6 Fig. 5. Effect of antitranspirant foliar treatments with linseed oil on the photosynthetic rate of durum wheat at the tillering stage under water deficit stress in glasshouse. CW: control, durum wheat, WT5: durum wheat treated with linseed oil at 5%, WT7: durum wheat treated with linseed oil at 7%, WT10: durum wheat treated with linseed oil at 10%, Water regimes: 25, 50, 75 and 100% of field capacity. Bars affected with the same letter are not significantly different at P Fig. 6. Effect of antitranspirant foliar treatments with linseed oil on the photosynthetic rate of barley at the tillering stage under water deficit stress in glasshouse. CB: control, barley, CB5: barley treated with linseed oil solution at 5%, CB7: barley treated with linseed oil solution at 7%, CB10: barley treated with linseed oil solution at 10%, Water regimes: 25, 50, 75 and 100% of field capacity. Bars affected with the same letter are not significantly different at P Tunisian Journal of Plant Protection 6 Vol. 5, No. 1, 2010

7 par les plantes est perdue par transpiration, la réduction de cette transpiration peut préserver de l eau absorbée et minimiser le stress des plantes. L objectif de cette étude est de déterminer les conditions physiologiques d utilisation de l antitranspirant sans affecter les échanges gazeux. Des essais ont été conduits sous serre vitrée pour étudier les effets d un antitranspirant l huile de lin sur certaines caractéristiques physiologiques du blé dur et de l orge. Les deux céréales ont été cultivées sous conditions de stress hydrique et pulvérisées par l antitranspirant deux fois, avec des concentrations de 5, 7 et 10%, aux stades tallage et élongation de la tige. Les mesures du potentiel hydrique foliaire et du taux de photosynthèse ont montré que le traitement a amélioré la rétention de l eau dans la plante sans réduction significative de l activité photosynthétique. L antitranspirant pulvérisé à deux concentrations (7 et 10%) sous déficit hydrique permet à la plante d économiser une certaine quantité d eau dans ses feuilles. Mots clés: Antitranspirant, blé dur, huile de lin, orge, physiologie végétale ملخص ورغي فتحي وغيث بوزيان وعلي علبوشي ومنصف بنحمودة وحاتم الشيخ محمد وسعاد علوي-رزقي وبوزيد نصراوي تا ثيرات رش زيت الكتان في بعض الخصاي ص الفيزيولوجية للقمح الصلب/القاسي والشعير تحت Tunisian Journal of Plant Protection 5: 1-8. ظروف إجهاد النقص الماي ي في البيت الزجاجي. تمكن مضادات التعرق من نوع الغشاء من التخفيض من التعرق النباتي عبر الثغور والقشيرة وآذلك التبادل الغازي. وباعتبار أن غالبية الماء الذي تمتصه النبتة يضيع عن طريق التعرق فا ن التخفيض في هذا التعرق يمكن من المحافظة على الماء الممتص والتنقيص من الا جهاد الماي ي للنبات. إن الهدف من هذه الدراسة هو ضبط الظروف الفيزيولوجية لاستعمال مضاد التعرق دون التا ثير في التبادل الغازي. تم القيام بتجارب في البيت الزجاجي لدراسة تا ثيرات المعاملة بمضاد التعرق زيت الكتان في الخصاي ص الفيزيولوجية للقمح الصلب والشعير. تمت زراعة الحبوب تحت ظروف إجهاد النقص الماي ي وتم رش مضاد التعرق مرتين بترآيزات 5 و 7 و %10 في مرحلتي التفريخ واستطالة الساق. بينت قياسات القدرة الماي ية للا وراق ونسبة البناء الضوي ي أن هناك تحسن في حفاظ النبات على الماء بدون حصول تناقص معنوي في نشاط البناء الضوي ي. مكن رش مضاد التعرق بكثافتين (7 أو %10) النبات تحت ظروف إجهاد النقص الماي ي من الاحتفاظ بكمية من الماء داخل الا وراق. آلمات مفتاحية: مضاد التعرق فيزيولوجيا النبات قمح صلب شعير زيت الكتان LIERATURE CITED 1. Ben Naceur, M. and Ben Salem, M Amélioration de l efficacité d utilisation de l eau chez le blé dur par l emploi d antitranspirants. Medit. 1: Carbonnier, J., Atcho, E., and Jossang, P Antitranspirants végétaux et régulateurs stomatiques: objets et limites. Pages In: Recherches et applications dans le domaine des antitranspirants stomatiques. J. Carbonnier, D. Laffray & A.C.C.T., Eds. France, 241 pp. 3. Glenn, D.M., van der Zwet, T., Puterka, G., Gundrum, P., and Brown, E Efficacy of kaolin-based particle films to control apple diseases. Plant Health Progress 10: Mokhtari, F., Elbadaoui, K., and Paul, R Association between productivity, water use efficiency and gas exchange in a water-limited environment. J. Food Agric. Environ. 4: Nasraoui, B Rôle des films antitranspirants dans la phytoprotection contre les maladies fongiques. Ann. INRAT 66: Osswald, W., Niehuss, M., Huber, W., and Elstner, E.F Support of non- Tunisian Journal of Plant Protection 7 Vol. 5, No. 1, 2010

8 host resistance by artificial leaf coating. J. Plant Dis. Prot. 91: Plaut, Z., Magril, Y., and Kedem, U A new film forming material which reduces water vapour conductance more than CO 2 fixation in several horticultural crops. J. Hort. Sci. Biotech. 79: Tunisian Journal of Plant Protection 8 Vol. 5, No. 1, 2010