الفهرس 
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Abstract
Two field experiments were conducted in summer seasons of 2015 and 2016 at Giza AgriculturalExperimental Station, Agricultural Research Center (ARC), Egyptto evaluate the effect of foliar spray with three antitranspirant agents: Potassium, Kaolin and Ascorbic acid” on two cultivars of sunflower plant (Giza 102 and Solala 120) under three levels of irrigations 100%, 80% and 60% of Et0. onyield and yield components and water productivity of sunflower (Helianthus annuus L.). Each experiment was laid out in split split plot design with three replicates. The main plots were occupied by irrigation levels (100%, 80% and 60% of Et0), while subplots contained three spraying treatments of antitranspirants agents i.e. Potassium at 1%, Kaolin at 3% and Ascorbic acid at 100 ppm in addition to control treatment (water), While the sub.sub plots were adapted to the two sunflower cultivars (Giza 102 and Solala 120).
The obtained important results could be summarized as follow:
1- Effect of irrigation levels, antitranspirant agents and their interactions on vegetative characteristics of two sunflower cultivar plants.
Results concluded that shoot dry weight of sunflower plant is sensitive to irrigation water deficit either at 60 or 90 days after sowing. Sunflower shoot dry weight/plant values were significantly decreased as irrigation water level, decreased than 100% of Et0.
Foliar application of antitranspirant agents increased to different extents shoot dry weight of sunflower plants in both the two experimental seasons. Potassium antitranspirant agent was the potent treatment in this respect and increased shoot dry weight of sunflower cultivar plant in the first and second seasons over the control .
The lowest shoot dry weight values in both seasons were obtained with the application of Ascorbic under 60% of irrigation compared with control. On the other hand, heaviest shoot dry weight values at 90 days after sowing in the first and second seasons were achieved at 100% of irrigation level followed by 80% then followed by 60% irrigation level.
Obtained data indicate that in both seasons, values of dry weight of head per plant were higher under irrigation 100% of Et0 than at 80% of Et0. Meanwhile, dry weight plant head at 60% of Et0 significantly lowest than those in 100% and 80% of Et0. Such trend was in both the two successive seasons.
Mild watered level (80%) and limited watered level (60%) treatments markedly decreased head dry weight of sunflower plant after 60 days from sowing in the first season by 4.5 and 12.7%, respectively than well-watered treatment (100%). Corresponding values in the second season were 4.5 and 12.9%, respectively.
Foliar application of antitranspirant agents increased to different extents head dry weight of sunflower plants at 60 days of sowing in both the two experimental seasons. Improvement in such trait was more pronounced under soil water deficit conditions (60% Et0).
Their no significant effects were recorded among interactions on head dry weight at 60 days of sowing in the two seasons.
Results indicate that head dry weight of sunflower plant 90 days old was significantly affected by all the first and second order interactions. Highest value of sunflower head dry weight was achieved from well-watered (100%). Plants treated with potassium antitranspirant. This finding is true in both the two experimental seasons and was more pronounced with Solala 120 than with Giza 102 cultivar. Contrary, the lighter head dry weight value was recorded with Giza 102 cultivar plants grown under limited watered conditions and not treated with antitranspirantagents. Limited watered treatment (60% of Et0) harmed photosynthetic activity of sunflower plant and decreased their dry matter accumulation in stem after 60 days from sowing than well-watered plants (100% Et0) in the 1st and 2nd seasons.
The application of Potassium, Kaolin and Ascorbic antitranspirant agents increased stem dry weight of sunflower plant under limited water level (60%) than their control in the 1st season by 11.0%, 9.5 % and 7.6%, and in the 2nd season by 12.6%, 10.5% and 8.2%, respectively.
Stem dry weight (g.) of sunflower plant at 60 days sowing was not governed by all the studied interactions. This trend was true in either the first or the second experimental seasons.
At 90 days the influence of irrigation of 100% of Et0 on weight of stem per plant was significantly performed better than under other irrigation levels and exceeded those obtained with 80% and 60% irrigation level treatments in the first season by7% and 23% respectively and in the second season by 6% and 22% respectively.
The application of Potassium, Kaolin and Ascorbic antitranspirant agents at 60% of Et0 increased stem dry weight of sunflower plant 90 days in the first season by 10.6 %, 8.6 % and % 6.7 respectively and by 11.5%, 8.3% and 7.2 % in the second season respectively of (90 days) of sowing. At 60 days the lowest value of dry leaves of sunflower per plant was achieved at 60% of Et0. Such trend is true in both the two experimental seasons. Potassium antitranspirant agent was the potent treatment in this respect and increased leaves dry weight in the first season over the control under 60%, 80% and 100% of Et0 by 11.5, 11.0 and 8.9%, respectively. Analogous values in the 2nd season were 15.4, 11.8 and 10.6% for the same respective soil moisture levels.
Heavier dry weight of leaves after 60 days of sowing were recorded with Solala 120 cultivar plants sprayed with potassium antitranspirant agent under well irrigation (100%) treatment. On the contrary, the lowest values were obtained with Giza 102 Cultivar plants grown under limited irrigation levels (60%) in control experimental plots. Such finding is true in both the studied two seasons.
At 90 dyes obtained results showed that dry weight of leaves per plant grown under limited irrigation level (60% of Et0) was decreased at 90 days of sowing in the two successive seasons than well-watered plants (100% of Et0) by 20 and 22%, respectively. Potassium antitranspirant agent was the potent treatment in this respect and increased leaves dry weight in the 1st season over the control under 60%, 80% and 100% of Et0 by 10.7, 11.0 and 9.0%, respectively. Analogous values in the 2nd season were 7.7, 23.1 and 9.0% for the same respective soil moisture levels.
Interaction between irrigation levels and antitranspirant agents slightly affected root dry weight of sunflower 60 days old in both the two experimental seasons. The highest value was recorded with application of Potassium at 60% of irrigation of Et0. (12.82 g./plant), while the lowest value was recorded with application of Ascorbic at 100% of irrigation (10.24 g./plant). Second season results revealed an almost similar trend to that obtained in the first season. The highest value was recorded with application of Potassium at 60% of irrigation of Et0. (12.45 g./plant ), whereas, the lowest value was recorded with application of Ascorbic at 100% of irrigation (9.98 g./plant).
Dry weight of sunflower plant 60% days old was significantly affected by the interaction between irrigation levels and sunflower cultivars (Ir x Cu) in both seasons. Solala 120 cultivar plants grown under limited irrigation conditions (60% of Et0) have the heaviest root dry weight values, whereas the lowest values were recorded with plants of Giza 120 cultivar under well-watered conditions. Such finding is true in both the two experimental.
Interaction between irrigation levels and antitranspirant agents slightly affected root dry weight of sunflower 90 days old in both the two experimental seasons. The highest value was recorded with application of Potassium at 60% of irrigation of Et0. (14.32 g./plant), while the lowest value was recorded with application of Ascorbic at 100% of irrigation (12.48 g./plant). Second season results revealed an almost similar trend to that obtained in the first season. The highest value was recorded with application of Potassium at 60% of irrigation of Et0. (14.06/ plant), whereas, the lowest value was recorded with application of Ascorbic at 100% of irrigation (11.87 g./plant). Dry weight of sunflower plant 60% days old was significantly affected by the interaction between irrigation levels and sunflower cultivars (Ir x Cu) in both seasons. Solala 120 cultivar plants grown under limited irrigation conditions (60% of Et0) have the heaviest root dry weight values, whereas the lowest values were recorded with plants of Giza 120 cultivar under well-watered conditions. Such finding is true in both the two experimental seasons
2- Effect of irrigation levels, antitranspirant agents and their interactions on physiological traits of two sunflower cultivar plants.
Water irrigation levels significantly affected leaf area/plant at all growth stages in the two seasons. Irrigation of 60% gave the lowest value of leaf area/plant Significant difference between the tested cultivars was recorded for leaf area/plant. Solala 120 gave the higher values at all growth stages in both seasons. antitranspirant agents, leaf area/plant significantly affected by the applied antitranspirant agents in 2015 and 2016 seasons. All interactions between the studied factors had no significant effect on leaves area/plant in both the two seasons.
Significantly governed by soil moisture %. The highest RWC% values were recorded with the 100% of Et0 followed by the 80% of Et0. However, the lowest RWC% value was obtained from irrigation at dry treatment (60% of Et0) treated with Ascorbic acid. Such finding was true in both the two seasons.
Spraying sunflower plants with Potassium at 100% in both seasons (2015-2016) significantly increased RWC% as compared with untreated plants.
Water stress (60% Et0) treatment sharply decreased sunflower plant height in both seasons. Contrarily, plant height was increased as irrigation water levels increased.
As for cultivars, Giza 102 gave taller plants than Solala. 120.Height of sunflower plant was positively affected by the application of antitranspirant agents. This trend was true in both the two experimental seasons, but it was more pronounced under drought stress conditions. Under 60% irrigation level, the application of Potassium, Ascorbic and Kaolin antitranspirant agent treatments increased height of sunflower plant in the 2nd season than the control by 4.9%, 3.4% and 2.6%, respectively.
Antitranspirant agents minimized natural plant transpiration rate and saved cell water to maintain the efficiency of physiological processes in stressed plant.
Irrigation levels had significant effect on stem diameter throughout the two seasons. Increasing irrigation levels from 60% of Et0 to 100% of Et0 significantly increased stem diameter in both seasons. Increasing soil moisture in the root zone increased the capacity of sunflower plants to accumulate dry matter.
Significant difference was observed between the two cultivars in this character. Solala 120 had higher stem diameter than Giza 102 in both seasons. With respect to antitranspirant agents significantly surpassed the control in stem diameter. Potassium at 100% at Et0 gave the highest mean value in 2015 and 2016 seasons.
Data presented display the influence of irrigation levels and antitranspirant agents on head diameter of the two sunflower cultivar plants. It is clear that head diameter trait was significantly affected by irrigation levels. Irrigation at 100% at Et0 produced the highest values of head diameter (cm) in the two seasons. Otherwise, irrigation at 60% at Et0 caused a marked reduction in head diameter in 2015 and 2016 seasons.
With respect to cultivars, data indicated that Solala 120 gave high head diameter as compared with Giza 102 in both seasons.
Results indicated that antitranspirant agents significantly surpassed control treatment for head diameter in both seasons. Application of potassium gave the largest head diameter. The interactions among the three studied factors had no significant effect on head diameter of sunflower plants in both seasons.
3- Effect of irrigation levels, antitranspirant agents and their interactions on yield and yield components of two sunflower cultivar plants.
The effect of irrigation levels and antitranspirant agents on 1000- seed weight of two sunflower cultivars in the two experimental seasons of 2015 and 2016. Seed index (1000-seed) weight values were significantly affected by irrigation level treatments in the two growing seasons. Irrigation at 100% of Et0 gave the heaviest 1000 seed weight followed by irrigation at 80% of Et0 in 2015, but the difference between there was not significant. However, in 2016 season irrigation at 100% of Et0 gave the highest value. In both seasons, irrigation at 60% of Et0 produced the lowest value of 1000-seed weight. The difference in 1000-seed weight between cultivars was significant in both seasons. Solala 120 Cultivar had heavier 1000-seed weight than Giza 102.
Seed yield/fed. was significantly affected by irrigation levels in the two seasons. Irrigation at 100% of Et0 gave the highest seed yield/ fed., whereas the lowest seed yield value was achieved by the limited watered treatment (60% of Et0 level). In comparison to the control, foliar spraying of antitranspirants especially with potassium under 60% of Et0 irrigation level caused significant increase in seed yield during the two growing seasons. Difference in seed yield (kg/fed.) between the two used cultivars was significant in both the two seasons. Solala 120 gave higher seed yield value and exceeded those obtained by Giza 102 cultivar by 36.6 and 46.6% in 2015 and 2016 seasons, respectively. As for interaction among the studied factors data showed that there were no significant effects on seed yield/fed. due to these interaction.
Biological yield /plant tended to increase by increasing water levels in both seasons. Irrigation at 100% Et0 gave the highest value, whereas the irrigation at 60% of Et0 gave the lowest value. The increases of biological yield/fed. with irrigation at 100% of Et0 may be due to the increase in seed yield, stover yield, dry matter accumulation, head diameter and weight of 1000-seed. As for cultivars, data exhibited that the two sunflower cultivars significantly differed for biological yield/ fed. in both seasons. Cultivar Solala 120 gave the higher yield/fed than Giza 102.
The interaction among all factors had insignificant effect on biological yield/fed. in the two seasons.
4- Effect of irrigation levels, antitranspitant agents and their interactions on chemical components of two sunflower cultivars.
Irrigation at 100% of Et0 produced the highest seed oil content% in both seasons. Otherwise, seed oil percentage under sever water limitation (60% of Et0) was considerably lower than under other treatments. Potassium followed by Kaolin was the effective in increasing significantly seed oil% value.Sunflower seed oil% value was governed significantly by cultivars. Seed oil % value of Solala 120 cultivar was higher than that of Giza 102 cultivar. Solala 120 in this respect was significant in both the two experimental seasons.
With regard to irrigation levels, it could noticed that oil yield/fed. was significantly affected by irrigation levels. Oil yield/fed. was increased as water irrigation levels increased, in both seasons. There were significant differences between the two tested cultivars. Solala 120 gave high oil yield (kg/fed.) value as compared to Giza 102. Such trend was fact in the both seasons of 2015 and 2016.This is may due to the superiority of Solala 120 in seed yield kg/fed. as well as in oil%. Interaction between irrigation levels and antitranspirant agents had significant effects on oil yield (kg/fed.). Combination between 100% of Et0 and Potassium antitranspiration agent significantly increased oil yield. This was true in the first and second seasons, compared to the control.
All antitranspirant treatments surpassed the control and without difference among their.
The effect of irrigation levels and antiranspirant agents on chlorophyll content of leaves of sunflower cultivars during the two seasons of 2015 and 2016. It is clear from the tabulated data that, chlorophyll content (total chl.) at flowering stage were higher under watered with 100% of Et0. on the other hand, 60% of Et0 recorded the lowest value of such trait in the two growing seasons.
Results of the present investigation cleared that the application of antitranspirant agents had exerted a profound improving impact on total chlorophyll values compared with untreated (control) plants. Potassium antitranspirant agent treatment exhibited the highest value in this respect.
Total chlorophyll content of sunflower leaves was judged by cultivar used. Superiority in this respect also still remains with Solala 120 cultivar. Impact of interactions between the studied interacted treatments on chlorophyll content of sunflower leaves were not great enough to reach the 5% level of significance.
Leaf proline content increased with sunflower plants exposed to water stress 60% at Et0 compared with 100% of Et0 and 80% of Et0 irrigation levels.
5- Effect of irrigation levels, antitranspirant agents and their interactions on water relations of two sunflower cultivars.
Maximum (1587 m3/fed.) of Potassium treatments at Et0100% of Et0) without control of (Giza 102) and minimum (811 m3/fed.) of ascorbic treatments Et0 60% of Et0) values were recorded under moisture levels, respectively.
WUE values for irrigation levels were significantly differed in both seasons. Irrigation at 60% of Et0 resulted high WUE value as compared with irrigation at 80, 100% of Et0.Concerning cultivars, data revealed that the WUE for Solala 102 was significantly higher than for Giza 102 in the two seasons. Reading antitranspirant agents results showed significant effect of the tested treatments on WUE values. All antitranspirant agents surpassed the control in both seasons. All interactions among factors under study due to WUE were not significant in 2015 and 2016 seasons.