Yield and Quality Traits of Some Flax Cultivars as Influenced by Different Irrigation Intervals

Flax is a potential winter crop for Egypt that can be grown for both seed and fiber. The study was conducted during two successive winter seasons of 2013/14 and 2014/15 in the experimental farm of El-Gemmeiza Agricultural Research Station, Agriculture Research Centre, Egypt. The objective of this work was to evaluate the effect of irrigation intervals (25, 35 and 45) on the straw, seed, oil, fiber yields and quality of flax cultivars (Sakha1, Giza9 and Giza10). Irrigation intervals significantly influenced all studied traits except oil percentage. Irrigated flax plants every 35 days gave the maximum values for all traits, while irrigation every 45 days gave the minimum values. In respect to cultivars, significant differences were found in most yield and quality characters. Furthermore, the performance of Sakha 1 cultivar was superior in main stem diameter, biological, straw yields per faddan, seed index, seed, oil yields per faddan and oil percentage. Meanwhile, Giza 10 cultivar highly significantly out yielded Giza9 and Sakha1 in plant height, fiber fineness, fiber length, total fiber percentage and fiber yield per faddan. The interactions between irrigation intervals and flax cultivars were highly significant for all traits. Based on the results, Sakha1 cultivar recorded the maximum values for main stem diameter, biological, straw yields per faddan, seed, oil yields per faddan and oil percentage and Giza 10 recorded the maximum values for plant height, fiber fineness, fiber length, total fiber percentage and fiber yield per faddan under irrigation of plants every 35 days.


Introduction
Flax (Linum usitatissimum L.), is one of the most versatile and useful crops and has been grown for thousands of years (Genser & Morris, 2003).Its oil types known as linseed considered one of the most important oil crops for the extraction of oil.About 80% of the linseed oil goes for industrial purpose and the remaining 20% is used for edible purposes (Asgharipour & Rafiei, 2010).It is a multi-purpose crop with benefits extending to both human and animal nutrition (Szilgyi, 2003).This reflects its very high content of essential fatty acids (EFAs), a high percentage of dietary fiber, and the highest level of "lignans" from any plant or seed products used for human food (Pandey & Agarwal, 1998).Flax is considered one of the most important dual purpose crops for oil and fiber production in Egypt and also in the world, rich in oil (41%), protein (20%), and dietary fiber (28%), (Bakry et al., 2012).Flax is an important economic crop which plays a role in our policy through its local fabrication as well as exportation.Although, the cultivated area in Egypt is relatively small and decreased dramatically in last decade, great reduction had happened in flax cultivated area (Aermae, 2007).
with other dual purpose and fiber types cultivars.In addition, Bauer et al. (2015) mentioned that, the higher fiber contents along with the higher straw yields resulted in the fiber-type cultivars yielding 60-70% more fiber than the seed-type cultivar.However, the seed-type cultivar had higher seed weight and seed yield than the fiber-type cultivar.Flax cultivars significantly differed in yield and its attributes (El-Kady et al., 1995;Abo-Zaid, 1997).Many investigators reported significant differences among flax cultivars concerning straw, seed, oil and fiber yields and their components (El-Hariri et al., 2004;El-Hariri et al., 2012;Barky et al., 2014).
Concerning to irrigation intervals, Chorumale et al. (2001) and Yenpreddiwar et al. (2007) mentioned that, two irrigations applied at flowering and capsule filling stages significantly increased the yield attributes, yield, oil content and oil yield of flax compared with no irrigation and irrigation at flowering stage only.In addition, Sharma et al. (2012) indicated that, irrigation at both 30 and 60 days after sowing (DAS) produced the highest values of growth characters compared with irrigation at 30 DAS only.Lisson and Mendham (2000) found that, irrigation increased flax straw and seed yield when precipitation was low and with poor distribution.Bauer and Frederick (1997) conducted a two-year study on flax in adjacent irrigated and rainfed areas and found the irrigated flax had approximately 1000 kg ha -1 higher straw yield.
It is necessary to increase flax productivity per unit area which could be achieved by using high yielding cultivars and improving the agricultural treatments (El-Sahrawi et al., 2008;Barky et al., 2013;El-Hariri et al., 2012).Therefore, in the recent years many efforts were devoted to increase the productivity of the flax through improving genetic traits and use of improved cultivars which have high yields and high water use efficiency.The cultivars and irrigation intervals were considered two of the main factors that affecting directly the growth and productivity of flax plants.With keeping the above points in view, the objective of this research were to evaluate the performance and response of some flax cultivars under different irrigation intervals.

Plant Material and Procedures
The present investigation was carried out at El-Gemmeiza Agriculture Research Station, Gharbiua Governorate, Egypt during the two successive winter seasons of 2013/14 and 2014/15 to study the performance and response of some flax cultivars to different irrigation intervals and their influences on straw, seed, oil and fiber yields and its components and quality attributes for these cultivars.The preceding crop was maize (Zea mays) in both seasons.The soil texture was clay loam, pH 7.7 and EC 0.40 in both seasons.Precipitation in the experiments area-generally didn't exceed potential evapotranspiration for most crops.As a result, all crops in this area get its needs of water by irrigation, especially surface irrigation.Worthy to mention that, average of precipitation for this experimental location was about 42 mm/m 2 in the winter seasons.
Field experiment was carried out each season using a split-plot design with three replications, and the irrigation intervals were plotted in the main plots.Three irrigation intervals were applied as follows: (25, 35 and 45 days) started after the first irrigation, which means (5, 4 and 3 irrigation times) taking into consideration the sowing and first irrigations.These irrigation intervals are frequently used by farmers under surface irrigation system in the fields of the surrounding areas.However, flax cultivars (Sakha 1, Giza 9 and Giza 10) were arranged in the sub-plots, where each sub-plot size was 6 m 2 (2 m × 3 m) or (1/700 fad.).The two experiments were sown on 27 and 29 October in the first and second season, respectively.Calcium super phosphate was added at the rate of 100 kg/faddan (15.5% P 2 O 5 ) before sowing and potassium sulphate (48% K 2 O) was applied in one dose at the rate of 50 kg/faddan before sowing in both seasons.Nitrogen was added to the sub-plots at the rate of 60 kg N/faddan in the form of urea (46% N) in two equal doses, the first half was added before the first irrigation and the second one was added before the second irrigation.Other recommended cultural practices for growing flax were done as usual in the area.

Sampling and Measurement
Ten individual plants were chosen randomly at full maturity for each sub-plot to record plant height (cm), main stem diameter (mm) and seed index (gm), while other traits were taken from whole plants of the plot.

Straw Yield and Its Related Characters
Plant height (cm): the distance from the cotyledonary node to the top of plant, main stem diameter (mm): at the middle region to the nearest 0.1 mm by using biocles, biological yield per faddan (ton) (faddan = 4200 m 2 ): estimated all plants from the sub-plots and converted to record biological yield per faddan before removing the capsules, and straw yield per faddan (ton): estimated from the sub-plots and converted to record straw yield per faddan after removing the capsules.

Seed Yield and Its Related Characters
Seed index (gm): It was determined as the average weight of 1000 seeds obtained from each sub-plot, seed yield per faddan (kg): seed yield of an area of each plot (6 m 2 ) was estimated and transformed to kg per faddan, oil percentage (%): was determined as described by the (AOAC, 1990) methods, using petroleum ether (40-60 °C) in Soxhlet apparatus and oil yield per faddan: was calculated from the following formula: Oil yield per faddan = oil percentage × seed yield per faddan 2.2.3 Fiber Yield and Its Technological Characters Fiber Fineness (N.m) determined using Radwan and Momtaz (1966) method according to the following equation: Where, N.m = Metrical number, N = Number of fibers (20 fibers and the length for each one = 10 cm), L = Length of fibers in mm (10 cm), and W = Weight of fibers in mg.
Fiber yield per faddan (Kg): calculated from plot fiber yield, Fiber length (cm): Ten fiber ribbons from each treatment were spreaded out and each ribbon was measured then the average fiber length was recorded, Total fiber percentage: It was calculated from the following formula: Total fiber percentage = × 100 (2)

Statistical Analysis
Using Michigan State University Computer Statistical Package (MSTATC), the analysis of variance was used for the two experiments according to Snedecor and Cochran (1982).The data was statistically analyzed for each season and the homogeneity of experimental error in both seasons was tested, then the combined analysis of data was performed for the characters over two seasons (Le Clerg et al., 1962) to present the main factors and its first and second order interactions.The least significant difference (LSD) test at 0.05 and 0.01 levels of significance was used to indicate mean comparison.

Straw Yield and Its Related Characters
The analysis of variance for the combined data with regard to plant height, main stem diameter, biological and straw yields per faddan showed highly significant differences among the three tested irrigation intervals as has presented in Table 1.It was observed that, irrigation every 35 days (4 irrigation times during the growth season) increased plant height, main stem diameter and straw yield per faddan and recorded the highest values for these traits followed by the irrigation every 25 days (5 irrigation times) which ranked the second.While the lowest values for all above mentioned traits were recorded by irrigation every 45 days (3 irrigation times).The only noticeable change in the data direction was irrigation every 25 days (5 irrigation times) recorded the highest values of biological yield per faddan with no significant difference with irrigation every 35 days (4 irrigation times).These results may be due to the reduction of plant growth which occurs as results for some responses to water deficit (irrigation every 45 days) from one side, and excess moisture (irrigation every 25 days) from the other side.It is known that, there is a decrease in the photochemical activity of photosynthesis, rubisco enzyme activity and the accumulation of secondary metabolites when plants are under water deficit stress as well as abscisic acid and solutes increase due to water reduction.These factors reduce stomatal conductance and consequently photosynthetic activity which ultimately resulted in a reduction in the synthesis of proteins and cell walls, as well as a decrease in the rate of cell expansion (Chavarria & dos Santos, 2012).On the other hand, flax plant has a retting after yield traw yield Fiber S shallow rooting system and needs adequate water in the 0-10 cm soil layer (Wood, 1997), and under excess moisture conditions, oxygen was often in short supply, normal exchange of gases from roots to soil was frequently disturbed and altered plant metabolism.Moreover, lodging was more pronounced under excess water conditions especially with high sowing rates.The sum of these responses contributes to explain the reduction of plant growth under excess moisture conditions.These results are in harmony with those obtained by Gabiana (2005) when he reported that, straw and total dry matter production was increased by irrigation compared with rainfed plants.Islam et al. (2011), Ahmadizadeh (2013), El sabagh et al. (2015a, 2015b), Abd El-Wahed et al. (2015a), and Barutçular et al. (2016) revealed that, drought stress causes a reduction in plant growth.De Carvalho et al. (2005) observed an increase in the plants height with increasing the water availability.Taiz and Zeiger (2006) stated that, lesser water availability tends to present lesser plant height, because the water restriction can affect the metabolic processes of growth.Flax is sensitive to water shortage and plant height reduced due to lack of water (Ahlawat & Gangaiah, 2009), Mirshekari et al. (2012) mentioned that, the highest plant height, biological yield and harvest index of flax were obtained from control irrigation treatment, while limited irrigation stress resulted in the lowest these traits.
In this study, the analysis of variance for the combined data showed highly significant differences among the three tested flax cultivars Sakha 1, Giza 9 and Giza 10 (Table 2).It was observed that, Giza 10 cultivar gave the tallest plants and recorded the highest values of plant height.However, Sakha 1 cultivar ranked the first and recorded the highest values of main stem diameter, biological and straw yields per faddan, followed by Giza 10 only in main stem diameter trait, while Giza 9 ranked the second in biological and straw yields per faddan.The present results are mainly due to the genetic differences and potentiality between the fiber and dual-purpose cultivars of flax.Sakha 1 (dual-purpose type) recorded the thicker stem diameter and surpassed other cultivars in seed yield and consequently surpassed it in biological and straw yields.However, Giza 10 (fiber type) gave the tallest plants.The effect of the first order interactions between (seasons × irrigation intervals), (seasons × flax cultivars) and (irrigation intervals × flax cultivars) on straw yield and its traits are presented in Figure 1.The interaction between seasons and irrigation intervals had only significant effect on main stem diameter and straw yield per faddan.Moreover, the interaction between seasons and flax cultivars had highly significant effect on main stem diameter.While, the effect of the interaction between irrigation intervals and flax cultivars on plant height, main stem diameter biological and straw yield per faddan was highly significant and Giza 10 cultivar recorded the highest plant height under irrigation every 35 days.Whereas, Sakha 1 cultivar recorded the highest main stem diameter, biological and straw yields per faddan under irrigation every 35 days.These results clearly indicated that, the cultivars significantly differed in their responses to the irrigation intervals.Results revealed that, the variability among tested flax cultivars which may be expected due to the differences of these cultivars in origin, growth habit and genetic constituent and the environmental conditions.

Seed Yield and Its Related Characters
The analysis of variance for the combined data with regard to seed index (gm), seed yield per faddan, oil percentage and oil yield per faddan showed highly significant differences among the three irrigation intervals (Table 4).Irrigation every 35 days (4 irrigation times during the growth season) was achieved the highest values for all previous mentioned traits without significant differences with both irrigation every 25 days (5 irrigation times) for seed index trait and irrigation every 45 days (3 irrigation times) for oil percentage.In addition, irrigation every 25 days (5 irrigation times) ranked the second, while irrigation every 45 days (3 irrigation times) recorded the lowest values and ranked the last for seed yield and oil yield per faddan.The best result for all these traits were obtained from irrigation every 35 days (4 irrigation times).It could be ascribed to favorable moisture conditions resulting from irrigations at critical physiological stages of initiation of flowering and seed filling.Adequate moisture may also increase photosynthesis which is responsible for carbohydrate formation, seed filling and final seed yield.On the other hand, it appears that water stress hampered flowering and reduced the probability of developing flower to capsule and its occurrence during flowering and capsule formation resulted in capsule abortion.These results are in agreement with those obtained by Gabiana (2005), when he found a significant positive effect on seed yield attributed to higher capsule numbers and more seeds per capsule under adequate water conditions.Meanwhile, flax plants subjected to water stress performed poorly in biomass production and yield.Mirshekari et al. (2012) mentioned that, the highest number of primary branches per plant, capsules number per plant, seed numbers per capsule, seed and oil yields per faddan and oil percentage of flax seed were obtained from control irrigation treatment, while limited water stress during flowering and seed filling stages resulted in lowest these traits.Bauer et al. (2015) inferred that, irrigation significantly increased seed weight, although it did not significantly impact on flax seed yield and the average of seed yield under irrigation was higher than rainfed condition.
The analysis of variance for the combined data with regard to seed index (gm), seed yield per faddan, oil percentage and oil yield per faddan as affected by the three tested flax cultivars Sakha 1, Giza 9 and Giza 10 are presented in Table 5.A highly significant variation was found among cultivars, and Sakha 1 cultivar recorded the highest values for all these traits, followed by Giza 9 cultivar with no significant differences between them only for oil percentage.However, the lowest values were recorded by Giza 10.These differences among the tested cultivars could be mainly attributed to the differences in their genetical construction and their response to the environmental conditions.The marked differences in seed index are mainly due to the differences in genetical make up of the tested cultivars.In addition, the variations among cultivars in seed yield per faddan and oil percentage are mainly due to the genetical variation possessed by the tested cultivars, and the increment in seed yield per faddan for Sakha 1 is attributed to the increase of number of capsules per plant, number of seeds per capsule (unpublished data) and seed index.Consequently, the increment in oil yield per faddan for Sakha 1 is attributed to the increment in seed yield per faddan and oil percentage.(2015) reported that, flax oil types realized the highest seed yield per faddan, oil percentage and oil yield per faddan followed by dual purpose types, while the lowest values were recorded by fiber types.Bauer et al. (2015) concluded that, the seed-type cultivar had higher seed weight and seed yield than the fiber-type cultivar.The differences between the tested cultivars could mainly be attributed to the differences in their genetical constitution and their response to the environmental conditions.In this connections, many investigators obtained higher levels of varietal differences in yield and its components in many regions (Kineber et al., 2006;El-Kady Eman & Abd El-Fatah, 2009;Abd El-Wahed et al., 2015b;EL Sabagh et al., 2016a, 2016b).
The effect of the first order interactions (seasons × irrigation intervals) and (irrigation intervals × flax cultivars) on seed yield and its traits are presented in Figure 2. The interaction between seasons and irrigation intervals had only significant effect on seed yield per faddan and oil yield per faddan.While, the effect of the interaction between irrigation intervals and flax cultivars had highly significant effect on all seed traits, and Sakha 1 cultivar recorded the highest value for seed index under irrigation every 25 days.Moreover, the same cultivar recorded The effect of the second order interaction (seasons × irrigation intervals × flax cultivars) on seed yield per faddan was only significant (Table 6), while Sakha 1 cultivar recorded the highest value under both irrigation every 35 days and every 25 days in the first season.

Fiber Yield and Its Technological Characters
The analysis of variance for the combined data with regard to fiber fineness, fiber length, total fiber percentage and fiber yield per faddan showed highly significant differences among the three tested irrigation intervals (Table 7).Irrigation every 35 days gave the finest fiber, the tallest fiber length, the highest total fiber percentage and the highest fiber yield per faddan, followed by irrigation every 25 days which ranked the second.While the most coarseness fiber, shortest fiber length, lowest fiber yield per faddan and lowest total fiber percentage values were obtained by irrigation every 45 days (3 irrigation times).The trend of these data was similar to the trend of straw yield and its related characters, which emphasize that, straw yield and plant height especially technical stem length (a long unbranched stem which contains the most high quality fiber) define the fiber biomass (Sankari, 2000).Similar trends were also stated by Elhaak et al. (1999) as a high percentage of valuable long fibers were a function of high soil moisture and fertility especially of N, P, K and Mg.Gabiana (2005) also mentioned that, the fiber yield per plant was three times more in irrigated plots than in rainfed plants.In other words, water stressed plants produced less fiber compared to irrigated plants with adequate water.Moreover, Bauer et al. (2015) reported that, irrigation increased fiber yield compared to rainfed plants.
The analysis of variance for the combined data showed highly significant differences among the three tested flax cultivars: Sakha 1, Giza 9 and Giza 10 (Table 8).Giza 10 cultivar gave the finest fiber, the tallest fiber length, the highest total fiber percentage and the highest fiber yield per faddan, followed by Giza 9, while the most coarseness fiber, the shortest fiber length, lowest fiber yield per faddan and lowest total fiber percentage values were obtained by Sakha 1.Such differences could be attributed to genetic constituents of cultivars, whereas, Giza 10 is a fiber type and Giza 9 and Sakha 1 are dual-purpose types.The fiber types gave the highest values of fiber percentage which were proportionally with the loss in straw yield per faddan after retting.The loss in straw yield per faddan after retting for dual-purpose (Giza 9 and Sakha 1) was higher than the other fiber type.These results are in agreement with these obtained by Abd El-Fatah (2007) and El-Refaey et al. ( 2010) and they reported that, fiber types exceeded dual and oil types in fiber fineness and it had superiority for fiber length character and recorded the highest fiber percentage and fiber yield per faddan.El-Azzouni and Zedan (2009) opined that, Giza 10 surpassed all other tested cultivars in fiber fineness.These results are in the same line with these obtained by Bauer et al. (2015) as they mentioned that, the higher fiber contents along with the higher straw yields resulted in the fiber-type cultivars yielding 60-70% more fiber than the seed-type cultivar.The effect of the first order interactions (seasons × irrigation intervals), (seasons × flax cultivars) and (irrigation intervals × flax cultivars) on fiber yield and its technological characters are presented in Figure 3.The interaction between seasons and irrigation intervals had highly significant effect on total fiber percentage, while it had only significant effect on fiber yield per faddan.Moreover, the interaction between seasons and flax cultivars had highly significant effect on total fiber percentage and fiber yield per faddan.In addition, the effect of the interaction between irrigation intervals and flax cultivars was highly significant on all fiber traits and Giza 10 cultivar recorded the highest values for all these traits under irrigation every 35 days.These results clearly indicated that, the cultivars significantly differed in their responses to the irrigation intervals and the variability among tested flax cultivars which may be expected due to the differences of these cultivars in genetic constituent and the environmental conditions (Khalifa et al., 2011;El-Hariri et al., 2012).

Conclusion
From this study, it can be concluded that, irrigation intervals have a significant role on flax production and irrigation every 35 days (4 irrigation times during the growing season) performed the best traits.Among the cultivars, Giza 10 cultivar was superior in plant height, fiber fineness, fiber length, total fiber percentage and fiber yield per faddan traits.Meanwhile, Sakha 1 cultivar highly significantly surpassed other cultivars in main stem diameter, biological, straw yields per faddan, seed index, seed, oil yields per faddan and oil percentage. Figure Figure 3

Table 1 .
Means of straw yield and yield traits as affected by irrigation intervals (combined data)

Table 2 .
Means of straw yield and yield traits as affected by flax cultivars(combined data) El-Refaey et al. (2009)od agreement with those obtained byAssar (2008), El-Refaey et al. (2010)andEl-Refaey et al. (2015), where they indicated that, fiber types were superior in total height compared with dual-purpose and oil types.However, dual and oil types surpassed fiber types in main stem diameter, biological and straw yields per faddan.El-Refaey et al. (2009)also reported that, ideal fiber types are characterized by the thin stem diameter.

Table 3 .
Interaction effects among seasons, irrigation intervals and flax cultivars on straw yield and is traits

Table 4 .
Means of seed yield and yield traits as affected by irrigation intervals(combined data)

Table 5 .
Abou-Zaied and Mousa (2007)ld traits as affected by flax cultivars (combined data) Such results are in harmony with those reported byZahana et al. (2003),El-Azzouni et al. (2003),Kineber (2004)andAbou-Zaied and Mousa (2007), where they found that, Sakha 1 flax cultivar significantly produced the highest values of capsules number per plant, seed index, seed yield per faddan, oil percentage and oil yield per faddan compared with other tested dual-purpose and fiber cultivars.El-Seidy et al. (2010)and El-Seidy et al.

Table 6 .
Interaction effects among seasons, irrigation intervals and flax cultivars on seed yield (per faddan trait)

Table 7 .
Means of fiber yield and its technological characters as affected by irrigation intervals (combined data)

Table 8 .
Means of fiber yield and its technological characters as affected by flax cultivars(combined data)

Table 9 .
Interaction effects among seasons, irrigation intervals and flax cultivars on fiber yield and its technological characters