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Abstract
In the present study, two field experiments were carried out at the experimental farm of the Faculty of Agriculture at Moshtohor, Benha University during the two successive seasons 2008 and 2009.
The aim of these experiments were to study the effect of spraying cotton with the growth retardant Paclobutrazol (PP333), growth Promoter Benzyladenine (BA), Fresh Yeast each alone in two rates of the low and high, and decapitation or topping (by cutting the tip of the main stem) in two physiological ages under two sowing dates (early – late), on the vegetative and reproductive growths, as well as on the anatomical features of leaves, pedicel of the third flower survived on the fruiting branch lied on the 4th node from the top of main stem as well as some fiber properties.
Cotton plants were foliar sprayed with Paclobutrazol (PP333) three times at 60, 80 and 100 days after sowing ,Benzyladenine (BA), sprayed three times at 85, 105 and 125 days after sowing using hand operated compressed air sprayer. Tween 20 as wetting and spreading agent with the rate of 1ml/litre was added to all spraying treatments with Paclobutrazol ( PP333) as foliar sprayers starting at the age of 60 days after sowing and Benzyladenine (BA), as foliar sprayers starting at the age of 85 days after sowing . Spraying in each time for each treatment took place uniformly with equal amount of spraying solution of the appropriate concentration of different assigned treatments. Each plant of each treatment sprayed with equal amount of spraying solution as all others.
Meanwhile, Fresh Yeast was added to the irrigation water starting with the first irrigation with the rate of 20 or 40 kg/feddan and repeated five times until the fifth irrigation.
In case of topping (decapitation), it was done by removing the terminal bud in the stage of 12 or 14 fruiting branches.
The obtained results could be summarized as follow:
1. Vegetative growth:
(a) The obtained results clearly showed that different used treatments were decreased the all vegetative characteristics i.e., plant height. Also, different treatments were decrease of the plant height in cm. number of internodes /plant average internodes length cm. after planting during 2008 and 2009 seasons.
(b) Moreover, the used treatments were highly increased concentration of chlorophyll a, b and carotenoids of cotton plant at both 105 days after planting during 2008 and 2009 seasons.
2. Chemical composition:
(a) The obtained results clearly showed that different applied treatments were increased planting during the assigned season.
3- Anatomical study:
The obtained results clearly indicate that vigorous growth of cotton plants treated with different applied treatments was positively correlated with different anatomical responses of during the vegetative and reproductive growths of cotton plant, samples for anatomical studies were taken as follows. Specimens were taken for the histological studies at the age of 120 days after sowing from:
Leaves the leaf lies on the node number four below the apical top. Since, different applied treatments increase thickness of mesophyll, thickness of lamina (Thickness of cuticle upper – lower, Thickness of upper and lower epidermis, thickness and number of palisade tissue, thickness and number of spongy tissue), thickness of Lamina, Thickness of midvein, Thickness of fiber, thickness and number resin ducts, thickness and number of collenchyma upper and lower tissue, length and width of main vascular bundle, thickness number of xylem tissue, thickness of phloem tissue and number of new formed like- bundles.
Remaining flower (third flower or flowering pedicel) specimens were taken in the base of flowering pedicel (i.e., the site of its connection with the fruiting branch i.e., the site of the abscission zone). Meanwhile, the longitudinal sections were taken from that segment includes a part of the base of flowering pedicel and small part of its fruiting branch. Since, different applied treatments increase of Diameter of whole section, Thickness of cuticle layer, Thickness of epidermal, Thickness of collenchyma, Thickness of parenchyma, Number of cortical layers, Thickness of cortex, Thickness of fiber layer, Thickness of phloem region, thickness and number of xylem region, thickness and number of resin ducts, thickness of fiber layers and (thickness and number of cortex lateral bundles
Stem anatomical features e.g. stem thickness; increment of stem thickness was accompanied with increases in most of its anatomical features, i.e., thickness of epidermis, thickness of cortex and increasing diminutions (length and width) of vascular bundles, thickness of both phloem, xylem tissues and number of xylem vessels.
Of interest is to note that these positive responses of different anatomical aspects to treatments were completely reversed upon vegetative and reproductive growth of treated plants. So, present study revealed those increases of xylem tissue, i.e., the route of mineral nutrients and water translocation from roots to leaves and the phloem tissue i.e., the pathway of different assimilates from leaves to fruits and other plant sinks (bolls). Thereby, improvement of translocation events directly could be considered a direct reason for increment the final cotton seed of yield.
In this respect, fresh yeast at the two rates, Paclobutrazol (PP333) at the two concentrations, Benzyladenine (BA) at the two concentrations, was the most effective treatment.
(4) Reproductive growth:
(a) The used treatments were increased the number of fruiting branches, number of opening flowers and number of bolls per plant, and decreased of the number of aborted flowers, this increase and decreased was more than the control plants with Fresh Yeast at the two rates, Paclobutrazol (PP333) at 10, 20 ppm, Benzyladenine (BA) at 10, 20 ppm and topping or decapitation at 12, 14 fruiting branch during 2008 and 2009 seasons.
(b) Paclobutrazol (PP333), Benzyladenine (BA) at the two applied concentrations (i.e., 10& 20ppm) significantly increased boll weight in the two sowing dates. Also, it could be noticed that Fresh Yeast gave the same significant increase of boll weight as well as the topping at 12 or 14 branches. Here, also it could be noticed that Paclobutrazol (PP333), yeast and Benzyladenine (BA) at the low applied concentration were more pronounced in the early sowing date while they were also the most active but in the two applied rates in the late sowing date, significant increase of boll setting was existed with each of PP333 and Benzyladenine (BA) with the two applied concentrations for each, i.e. 10 and 20 ppm). Also, in case of topping at 12 or 14 branches, significant increase was existed in the number of sated bolls. On the other hand, Fresh Yeast at the two rates applied showed insignificant increase of seted bolls in the early sowing date, meanwhile, it was reached to the significant levels in the late date of sowing. The above mentioned results of great interest, since increasing of seted Bolls directly will be reversed upon the reduction of Boll shedding and increasing the final yield.
(c) Paclobutrazol (PP333) at 10 and 20 ppm gave the highest significant increase of lint yield per plant since it gave 29.4 & 32.6 and 42.2 & 74.6% more than the control for the early and late dates of sowing with 10 and 20ppm, respectively. Also, it could be noticed that Paclobutrazol was followed by Benzyladenine (BA) in the second order and with Fresh Yeast in the third. That was true either in the early date of sowing or even the late one. Different applied treatments gave insignificant increase of lint percentage also Fresh Yeast at 40kg/feddan followed by topping at 14 branches yet; BA at 10ppm showed insignificant reduction of this aspect.
Also, the two sowing dates didn’t show significant result of this treatment. But for the interaction sowing date and the applied treatments gave insignificant increase of this aspect. The highest insignificant increase (37.83) existed with Paclobutrazol (PP333) at 10ppm and Fresh Yeast at 40kg/feddan during the early sowing date. For the 2009 season nearly the same results were obtained exception was only that significant increase with Benzyladenine (BA) at 10ppm (39.1) and Paclobutrazol (PP333) at 10ppm (38.3) during the early sowing date.
(d) Paclobutrazol (PP333), Benzyladenine (BA) at 10 & 20ppm, Fresh Yeast at 20 & 40kg/feddan and topping at 14 branches significantly increase Seed cotton yield kentar/feddan. The only topping at 12 branches exhibited insignificant increased of this aspect. Also it could be noticed that Paclobutrazol (PP333) at the two applied concentrations followed by Fresh Yeast, Meanwhile, Benzyladenine (BA) at the two applied concentrations ranked the third in this respect.
On the other hand, as for the sowing date each of them gave significant increase of seed cotton yield kentar/ feddan but the early sowing date was more pronounced in this respect. With regard to the interaction between sowing date and treatments it could be noticed that significant effect was existed and PP333 at the two applied concentrations gave the highest increase when compared with other treatment followed by Fresh Yeast at the two applied rates. Also, it could be noticed that during 2009 season nearly showed the above mentioned results of 2008 season
(e) seed index (the weight of 100 seeds) during the two seasons of 2008 and 2009 different applied treatments at the two sowing dates significantly increased this aspect the highest increase of this respect existed with Paclobutrazol (PP333) at 10ppm (10.76) and Fresh Yeast at the first rate, as well. Meanwhile, in 2009 season heighest significant increase (i.e.,) 11.1g with PP333 at 10ppm and 11 g. with second rate of Fresh Yeast were existed. As for the effect of sowing date on the seed index as shown in Table (13) during 2008 and 2009 season insignificant increase were existed. As regards the interaction between sowing date and treatments it could be noticed that this effect was significantly in 2008 season. But did not reach the level of significance in 2009. also, it could be noticed that highest significant increase in 2008 season was existed with Paclobutrazol (PP333) at 10 & 20ppm that reached 10.36 and 11.29, respectively, followed by 11.34 and 10.95 with 20kg and 40kg Fresh Yeast, respectively.
(f) All applied treatments increased the oil percentages in seeds at the harvest time. This increase reached its maximum with topping at 12 fruiting branch, (19.56 %), PP333 10 ppm (19.53%) followed by Yeast at level (1) (19.36%) and BA at 10 ppm (19.13%), yet, the treatment of topping at 14 fruiting branch gave the lowest increase of oil % comparing with the control.
Data in Table (15) indicate that each of Paclobutrazol (PP333) and Benzyladenine (BA) at the two applied concentration, topping at 14 branches and Fresh Yeast at the second rate insignificantly increased the fiber length in the two season. Yeast, its insignificant reduction was existed with each of topping at 12 branches and the Fresh Yeast at the first rate .
CONCLUSION
The aim of these experiments were to study the effect of spraying cotton with the growth retardant Paclobutrazol (PP333), the growth regulator Benzyladenine (BA),each alone in two rates of the low and height Fresh Yeast and decapitations (by cutting manual the tip of the main stem) in two physiological ages, on the vegetative and reproductive growths, as well as on the anatomical features of leaves, pedicel of the third flower survived on the fruiting branch lied on the 4th node from the top of main stem as well as some fiber properties on cotton G. barbadense cv. Giza 86. Paclobutrazol (PP333) at the two applied concentrations (10 -20 ppm) significantly decrease in both time of sowing (i.e., early and late) could help achieving higher seed cotton productivity, significantly increase also, Benzyladenine (BA) and Fresh Yeast significantly increase should be used to improve cotton growth, seed yield , quality of Giza 86. In comparison with the ordinary cultural practices adopted by the Egyptian cotton growers. The in¬crease in seed cotton yield and the percentage of oil due to increased PP333 and the application of BA and Fresh Yeast are believed to be sufficient enough to cover the cost of using those chemicals. Hence, it seems that there will be an opportunity to economical profit in comparison with the usual cultural practices adopted by Egyptian