EFFECT OF SUPPLEMENTARY IRRIGATION ON SEED YIELD AND OIL QUALITY OF SUNFLOWER ( Helianthus annuus L.) GROWN IN A SUB-ARID ENVIRONMENT

Transcription

1 EFFECT OF SUPPLEMENTARY IRRIGATION ON SEED YIELD AND OIL QUALITY OF SUNFLOWER ( Helianthus annuus L.) GROWN IN A SUB-ARID ENVIRONMENT Z. Flagella, T. Rotunno, R. Di Caterina, G. de Simone, L. Ciciretti, A. De Caro Università di Foggia, Facoltà di Agraria,Via Napoli 25, 71 Foggia, ITALY Fax : ; proveg.fgagr@isnet.it Summary It is well known that sunflower is a crop well adapted to sub-arid environments. However, notwithstanding a lot of information on sunflower s yield response to water deficit is available, very few data are reported on seed oil quality under rainfed and irrigated conditions. The aim of this paper was to evaluate the changes in seed yield and quality of standard and high oleic sunflower cultivars when submitted to supplementary irrigation in a sub-arid environment. The study was conducted in 1996 and 1997 in a farm located in Cerignola (Southern Italy; E, N), on two high oleic hybrids (Platon and Vyp 7) and two standard ones (Akiles and Romsun HS9), sown in spring. Supplementary irrigation was applied, at the two most critical developmental stages bud appearance and flowering, by replenishing the.6 m soil profile to field capacity. At harvest, yield and its main components were evaluated and later on analysis of oil fatty acid composition was carried out by gas liquid chromatography. Yield and its components were positively affected by irrigation in all the cultivars examined. The irrigation treatment resulted in a decrease of oleic and stearic acid and in an increase of linoleic and palmitic acid content. The cultivars showed a different sensitivity to irrigation.

2 Introduction Sunflower cultivation has increased in recent years (FAO yearbook, 1996) because of its moderate agronomic requirements and the good quality of the seed oil for edible purpose. Moreover, high oleic cultivars have been developed (Soldatov, 1976; Skillicorn, 1994) whose oil has a higher oxidative stability and better dietary properties than oils from standard cultivars. Sunflower is a crop well adapted to sub-arid environments, due to its ability to extract water from deeper soil layers by the marked development of the root system under water stress (Tarantino, 1979; Connor and Jones, 1985; Cox and Jolliff, 1986, 1987). However, it has been reported that the crop is particularly sensitive to water stress conditions from early flowering to achene filling (Unger, 1982; Quaglietta Chiarandà and D Andria, 1994) and that irrigation applied at these critical stages always gives similar yield response with respect to the periodic replacement of calculated crop evapotranspiration (Unger, 1978; D Andria et al.,1995). Notwithstanding a lot of information is available on sunflower s yield response to irrigation, very few data are reported on seed oil quality under rainfed and irrigated conditions. Moreover, fewer data are reported on the more recently developed high oleic hybrids.the aim of this paper was to evaluate the changes in seed yield and quality of standard and high oleic sunflower cultivars when submitted to supplementary irrigation in a sub-arid environment. Materials and methods The study was conducted in 1996 and 1997 on a farm located in Cerignola ( Southern Italy; E, N ) on a soil whose main characteristics are reported in Table 1. Two high oleic sunflower hybrids (Platon and Vyp 7, developed from AGRA) and two standard ones (Akiles and Romsun HS9) were sown on 26 March 1996 and 28 March 1997, under rainfed and irrigated conditions. In the irrigation treatment, water was applied at two growth stages considered as critical for seed yield (flower bud appearence- B and flowering- F) in order to replenish the.6 m soil profile to field capacity. The amount of water applied in each situation was based on gravimetric measurements of soil water content, along the.6 m soil profile; the irrigation volumes were 59.4 mm at B, 73.6 mm at F in 1996 and 83.1 mm at B and 71.2 mm at F in In 1996 and 1997, the irrigation dates were 15/6 and 8²/6 at B and 3/7 and 25/6 at F, respectively (Fig.1). A randomized split plot design with four replications was used with water regimes as large plots, sowing date as plots and genotypes as subplots of 29 m 2. Plants were sown in rows.7 m apart, with the seeds placed.25 m apart within the row, to provide a population density of about 5.7 plants/m 2. All the other cultural practices were the ones generally used in the area where the experiments were conducted. At harvest (occurred on 18 Aug. for the rainfed treatment and on 5 Sept. for the irrigated one in 1996 and on Aug. for the rainfed and on 25 Aug. for the irrigated treatment in 1997), yield and its main components were evaluated on a test area of 5.6 m 2 Table 1. Main soil characteristics Soil characteristics Values Sand (%) 66 Silt (% ) 14 Clay (% ) ph (in water) 8,8 Total lime (%) 85 T otal nitro gen (K jeld a hl m etho d, ) 1,4 Assimilable phosphorus (Olsen method, ppm P 2 O 5 ) 22 Exchangeable potassium (ammonium acetate method, ppm K 2 O) 745 Organic matter (Walkley Black method, %) 2,2 Field capacity (.3 MPa, % dry weight) 29. W ilting point (-1.5 MPa, % dry weight) 11.

3 Achene oil was extracted by using a Soxhlet type extractor. The fatty acid composition of sunflower oil was determined by using a Fisons model GC-816 gas chromatograph (Italian Fisons, I- Milan, Italy) as reported in Flagella et al.(). Data were analyzed using the Anova procedure of the MSTAT statistical package and differences between means were compared according to the SNK s test. Principal component analysis (PCA) was used on a data set of 64 objects (oil samples from 4 genotypes, 2 water regimes, 2 years and 4 replications) and variables (fatty acids). This multivariate method reduces the number of variables according to their redundancy and finds linear combinations of the variables (or components) with the first principal component having the largest variance, the second principal component with the second largest variance and so on. Before applying this method it was necessary to autoscale the data set in order to equalize the variance of the different factors (Massart et al. 1988) rainfall '96 rainfall '74'/94 mean temp. '96 mean temp. '74/'94 IRR NONIRR 35 rainfall (mm) temperature ( C) Jan Feb March Apr May Jun Jul Aug Sep rainfall '9 7 rainfall '7 4 /'94 mean temp. '97 mean temp. '74/'94 IR R NONIRR 35 rainfall (mm) temperature ( C) 5 Jan Feb M arch Apr M ay Jun Jul Aug Sep Fig.1. Rainfall and temperature trends in the two experimental years 1996 and 1997 compared with - yr ( ) mean values. The upper and the lower lines represent the length of the growing cycle for the irrigated (irr) and nonirrigated (nonirr) treatm ents. T he arrows indicate the irrigation times.

4 Climatic conditions Climatic patterns in 1996 and 1997 were fairly typical of a Southern Italian environment with rainfall characterized by higher precipitation events in winter and spring and lower rainfall from June to August (Fig.1); mean daily temperature generally increases from -12 C in March to C at the end of July, then decreases to 18 - C in September. However, in 1997 lower rainfall before sowing and an unusual lower temperature in April, were registered with respect to 1996 and the -year mean (Fig.1). Results and Discussion Yield and its main components were all significantly affected by growing season,water regime and genotype. The higher rainfall in 1996 and the irrigation treatment caused a better yield performance due to an increase of head diameter, seed number and mean seed weight and a decrease of head sterile surface. Also oil yield was positively influenced by a better soil water status (Table 2). The highly positive effect of irrigation on seed yield confirms the key role of supplementary irrigation in critical stages for seed yield development, particularly sensitive to water stress (Unger,1982; Rizzo et al.,1989; Quaglietta Chiarandà and D Andria,1994). The higher yield values observed in 1996 were probably due to the higher soil water content at seeding (Jones, 1984). Table 2. Effect of year, water regime and genotype on seed yield, its main components and oil yield. Values followed by the same letter are not significantly different, according to SNK s test at P.1. YEAR WATER REGIME GENOTYPE irr nonirr Platon Vyp 7 R. HS 9 Akiles Achene yield (t ha -1 ) 2.8 A 1.2 B 2.6 A 1.4 B 2.1 A 2. A 2.1 A 1.8 A Calathide diameter (cm) 15.6A 12.9 B 15.5 A 13 B 13.9 B 13.8 B 15.3 A 14.4 B Sterile surface (%) 4.3 B 16.1 A 6.3 B 14.2 A 6.7 C 9.3 BC 14.2 A.6 B achene weight (g) 43.6 B. A 41. A 31. B 38.3 A 35.2 B.5 A 33.3 A Achenes per calathide (n ) 1 A 73 B 8 A 76 B 92 AB 97 A 85 B 94 AB Oil yield (%) 51.4 A 49.9 B 51.7 A 49.7 B 48.4 C 5 B 52.3 A 52.1 A Table 3. Effect of year, water regime and genotype on sunflower oil fatty acid (a) composition. Values followed by the same letter are not significantly different according to SNK s test at P.1. YEAR WATER REGIME GENOTYPE irr nonirr Platon Vyp 7 Akiles R. HS 9 14:.1 A.1 A.1 A.1 A.4 C.4 C.12 A.7 B 16: 4.7 A 4.8 A 4.9 A 4.7 B 3.1 D 4.2 C 6.3 A 5.5 B 18: 3.8 A 3.9 A 3.7 B 4. A 4.4 A 3.6 B 4.3 A 3.2 C 18:1 6.4 A 6.6 A 58.9 B 62.1 A 83.4 A 79.2 B 25.6 D 53.9 C 18: A 29.1 A.6 A 27.4 B 7.1 D 11.2 C 62.1 A 35.7 B 18:3.2 A.2 A.2 A.2 A.1 C.1 C.4 A.2 B :.3 A.3 A.3 A.3 A.4 A.3 B.3 B.3 B :1.2 A.2 A.2 A.2 A.2 A.2 A.1 B.2 A 22:.7 A.7 A.7 A.7 A.9 A.7 B.6 C.7 B 24:.3 A.3 A.3 A.3 A.3 A.3 A.3 A.3 A a As methyl esters. 14: = myristic acid; 16: = palmitic acid; 18: = stearic acid; 18:1 = oleic acid; 18:2 = linoleic acid; 18:3 = linolenic acid; : = arachidic acid; :1 = gadoleic acid; 22: = behenic acid, 24: = lignoceric acid.

5 Among the four genotypes under study, Akiles showed the lowest yield due to its -achene weight. The two high oleic genotypes, Platon and Vyp 7, showed the lowest oil yield, calathide diameter and sterile surface. With regard to oil fatty acid composition, while the year effect was not significant, both irrigation and genotype showed a significant effect. The irrigation treatment caused a decrease in oleic and stearic acid and an increase in linoleic and palmitic acid (Table 3). Among the two high oleic genotypes, Platon showed the higher oleic, stearic and behenic acid content and the lower linoleic and palmitic acid content. Among the two standard genotypes, Romsun HS9 showed the higher oleic, eicosanoic, behenic and the lower linoleic, linolenic, stearic and palmitic acid content. A significant genotype x water regime interaction was found (Table 4). While the high oleic genotypes Platon and Vyp 7 showed a low decrease in oleic acid (3%) and a higher increase in linoleic acid (25 and 55%, respectively) under irrigation, the two standard genotypes Akiles and Romsun HS9 showed respectively no variation and a 13% decrease in oleic and a 24% increase in linoleic acid under irrigation (Table 4). The influence of genotype and water regime on oil fatty acid composition was evaluated also by the principal component analysis (PCA) whose results are graphically represented in a two dimensional plot (Fig.2). According to one way analysis of variance ANOVA (Table 3) also PCA showed higher differences among the four hybrids and lower differences between the water regimes, with the separation of the clusters occurring on the first principal component retaining most of total variance (6%). The fatty acids with the higher weight along the first principal component were 18:1, :1 and 22: discriminating the cultivar Platon and the nonirrigated treatment, and 16: and 18:2 discriminating the cultivar Akiles and the irrigated treatment. While a lot of data are available about the positive effect of irrigation on sunflower yield response, contrasting and scarce are the data in literature on the effect of water regime on sunflower oil quality. We found that the main effect of irrigation was an increase in linoleic acid content and a concurrent decrease in oleic acid in accordance with Talha and Osmond (1974) who observed a clear tendency for an increase in the ratio of oleic/linoleic acids under water stress. On the other hand, Unger (1982) reported that early season water stress increased oleic and decreased linoleic acid concentration, while Salera and Baldini (1998) found no effect of water management on oleic acid content Table 4. Effect of genotype x water regime interaction on sunflower oil fatty acid (a) composition. Values followed by the same letter are not significantly different according to SNK s test at P.1. Platon Vyp 7 Akiles Romsun HS 9 irr nonirr irr nonirr irr nonirr irr nonirr 14:.4 B.4 B.4 B.5 B.13 A.11 A.7 AB.7 AB 16: 3.2 E 3. E 4.5 C 4. D 6.3 A 6.3 A 5.6 B 5.4 B 18: 4.3 AB 4.5 A 3.3 C 3.9 B 4.2 AB 4.4 A 3. C 3.4 C 18: B 84.9 A 78. D 8.5 C 25.8 G 25.3 G 5.1 F 57.7 E 18:2 8.6 F 5.6 G 12.4 D 9.9 E 61.8 A 62.3 A 39.6 B 31.9 C 18:3.1 D.1 D.1 D.1 D.5 A.3 B.2 C.2 C :.4 A.4 A.3 B.3 B.3 B.3 B.3 B.3 B :1.2 A.2 A.2 A.2 A.1 B.1 B.2 A.2 A 22:.9 A.9 A.7 B.7 B.6 C.6 C.7 B.7 B 24:.3 A.3 A.3 A.3 A.3 A.3 A.3 A.3 A a As methyl esters. 14: = myristic acid; 16: = palmitic acid; 18: = stearic acid; 18:1 = oleic acid; 18:2 = linoleic acid; 18:3 = linolenic acid; : = arachidic acid; :1 = gadoleic acid; 22: = behenic acid, 24: = lignoceric acid.

6 Second principal component : 18:2 14: 24: Platon irrigated Platon nonirrigated Vyp 7 irrigated Vyp 7 nonirrigated R. HS 9 irrigated R. HS 9 nonirrigated Akiles irrigated Akiles nonirrigated :1 18:1 22: -2 18:3 18: : First principal component Fig. 2. Principal component analysis of the fatty acid composition of 64 samples from 4 sunflower hybrids (Platon, Vyp 7, R. HS 9, Akiles) grown under two water regimes, irrigated and nonirrigated, in 1996 and 1997 growing seasons. These different results are probably due to the different experimental growth conditions adopted by the different authors, which points out that other environmental factors such as temperature (Harris et al.,1978; Robertson et al.,1978; Sarmiento et al.,1998), may have a major effect on sunflower oil characteristics. REFERENCES Connor, D. G. and Jones, T. R Field Crops Res. 12: Cox, W. J. and Jolliff, G. D Agron. J. 78: Cox, W. J. and Jolliff, G. D Crop Sci. 27: D Andria, R.; Quaglietta Chiarandà, F.; Magliulo, V. and Mori, M Agron. J. 87: FAO Production yearbook. 1996, 5, ISSN Flagella, Z.; Rotunno, T.; Tarantino, E.; Di Caterina, R. and De Caro, A.. Submitted for publication. Harris, H. C.; McWilliam, J. R. and Mason, W. K J. Agric. Res. 29: Jones, O. R Agron. J., 76: Massart, D. L.; Vandeginste, B. G. M.; Deming, S. N.; Michotte, Y. and Kaufman, L In Chemometrics:a textbook, Amsterdam, Elsevier Quaglietta Chiarandà, F. and d Andria, R Eur. J. Agron. 3 (1): Rizzo, V.; Di Bari, V. and Quaranta, F Irrigazione e drenaggio 3: Robertson, J. A.; Chapman, JR. G. W. and Wilson, JR JAOCS, 55: Salera, E. and Baldini, M Helia 21(28): Sarmiento, C. ; Garcés, F. and Mancha, M Planta. 5: Skillicorn, A Food Proc. 55: Soldatov, K. I In Proc. 7 th International Sunflower onference, Krasnodar, USSR; Int. Sunflower Association: Vlaardingen, The Netherlands Talha, M. and Osman, F J. Agric. Sci. Camb. 84: Tarantino, E In Proc. Annu. Symp. A.I.G.R., 3 rd, Catania, Italy, May, Unger, P. W. July In Proc. 8 th In Sunflower Conf., Minneapolis, Minn. International Sunflower Association, The Hague, Netherlands Unger, P. W Soil Sci. Soc. Am. J. 46: