تأثير موعـد رش وتركيز حامض الجـبرلين GA3 في النمو والحاصل وامتصاص بعـض المغـذيات لـنبات الكــجرات Hibiscus sabdariffa L.

The Effect of Spraying Date and Concentration of gibberellic Acid GA3 on Growth,Yield and Absorption of some Nutrients of Roselle Plant . (Hibiscus sabdariffa L.)

SUMMARY

The experiment was conducted in a private field at AL-Bargah district (30 km) North east Kerbala city from March ,25th to October ,15th .
The aim of the experiment was to determine the effect of spraying date and different levels of Gibberrellic acid (GA3)(i.e.0,100,200, and 300 mg/l) on the growth , yield and absorption of some nutrients of roselle plant(Hibiscus sabdariffa L.).
The treatment were applied either at (4-6)leaf stage or before flowering stage of plants .
Randomized complete block design (R.C.B.D)with three replications was adopted. The least significant difference (L.S.D) at 5% prabability level was used as a method of mean seperation whenever treatment effect was evident . Results could be summarized as follow:

1-The first date of spraying led to a significant increase in plant height ,number of branches ,number of leaves ,leaf area ,,fresh weight of stems,dry weight of leaves,dry weight of sepals and dry weight of seeds,whereas ,the second date of spraying led to an increase in number of fruits,dry weight of stems,fresh weight of fruits and fresh weight of sepals.

2-Increasing gibberrellic acid concentration led to a significant increase in the above mentioned characteristics, meanwhile,the number of branches was decreased.

3-The interaction between the date of spraying and concentrations of gibberrellic acid showed a significant influence on plant height number of leaves leaf area , fresh weight of stems , fresh weight of leaves , dry weight of stems , dry weight of leaves , number of fruits , fresh weight of fruits , fresh weight of sepals , dry weight of sepals and dry weight of seeds .

4. There was no significant effect of the date of spraying on the concentration of nitrogen , phosphorus , potassium calcium and magnesium ( dry matter basis ) of sepals . Whereas , the first date of spraying led to a significant increase in sepals content of nitrogen , phosphorus ,potassium ,calcium and magnesium (g\ plant) .

5. Increasing gibberrellic acid concentration led to a significant increase of the obove mentioned nutrients . On the other hand , magnesium concentration and content of sepals were decreased when gibberrellic acid concentration was increased .

6. The interaction between the date of spraying and the gibberrellic acid concentractions showed a significant effect in sepals content of nitrogen
,phosphorus potassium and calcium (g \ plant ) .