THE EFFECT of GA 3 AND SALINITY on GROWTH of ROSELLE ( Hibiscus

In order to alleviate the deleterious effects of salinity, different types of phytohormones have been used. Among them, GA 3 has been the main focus of some plant scientists. This study aimed to evaluate the effect of gibberellic acid and salinity on growth and production of roselle ( Hibiscus sabdariffa L). This research was conducted in a greenhouse of Agriculture Faculty, University of Sumatera Utara, Medan. The study used utterly randomized design with two factors. The first factor was gibberellic acids. They were gibberellic acid (5 mg L -1 ) and no gibberellic acid. The second factor was salinity. They were 0 dsm -1 and 4-5 dsm -1 . The interaction between gibberellic acid and salinity acid indicated a significant effect on the percentage of germination, chlorophyll a and b and beta-carotene. The application of giberellic acid helped in the tolerance of plants to salinity. Thus, application of GA 3 become essential to improve overall productivity in salinity.


INTRODUCTION
The conversion of agricultural land to residential and industrial areas has resulted in a reduction in agricultural land. This causes agricultural development to be directed at marginal lands such as saline soils. Saline soil is soil that contains a certain amount of neutral dissolved salt which adversely affects plant growth and production (Kusmiyati et al., 2014).
Rosella flower (Hibiscus sabdariffa L.) contains compounds that have antioxidant activity, so they can ward off free radicals.
The usefulness value of roselle is very wide for both food and health, so that the potential for roselle diversification is quite large. The important content contained in rosella flower petals is an anthocyanin pigment which acts as an antioxidant (Nasifa and Husni, 2018

MATERIALS AND METHODS
In order to study the effects of The seeds were disinfected by alcohol 70% (for 10 seconds), sodium hypochlorite 10% (for 60 seconds) and benomyl 2:1000 (for one minute) Afterward, the seeds were rinsed with distilled water twice.
Gibberellic acid treatment. Seeds were soaked in 500 ml of distilled water for 12 hours (no GA3), and the seeds were immersed in 500 ml of a solution of GA3 for 12 hours and then redried to original weight with forced air under shade.

Salinity treatment.
To apply the salinity treatment, the salty soil was taken from the Kecamatan Percut Sei Tuan, which was measured for its salinity using a DHL meter at a salinity level of 4 dSm-1. Measurements were made by taking saline soil samples, then drying them in the sun, then the saline soil weighed 10 grams per sample.
Then put the soil sample into a beaker glass and add distilled water to 100 ml. then measured the salinity level using a DHL meter.
Planting. The seeds were germinated directly on the polybag according to each treatment.

RESULTS AND DISCUSSION
Gibberellin and salinity stress conditions showed a significant effect on the growth and production variables of roselle such as the percentage of germination, chlorophyll a and b, beta-carotene (Table 1) The developing fruit and seeds are the GA 3 biosynthetic pathway. Moosavi et al., (2013) reported that salinity stress had a negative impact on germination rate, germination percentage, long sprouts, shoot length and roselle seed viability index (Hibiscus sabdariffa). Overall, salinity through increased osmotic pressure leads to a reduction in water uptake and metabolic and physiological processes will come under its influence. So that it causes delays in germination by increasing seed germination.
Salinity not only affects leaf morphology and transpiration rate but also leads to a reduction of total chlorophyll content as the salt concentration increases.

CONCLUSION
Gibberellic acid (5 mg L-1) and salinity (4-5 dsm-1) on growth and production of roselle help maintain germination success although chlorophyll a and b decreased and was not formed flowers (generative phase) to be harvested.