Iranian Journal of Seed Research

An experiment was conducted to investigate the effects of jasmonic and humic acids on some seed germination characteristics of Roselle under the salt stress condition in a factorial experiment, adopting a completely randomized design with three replications. Treatments included four different levels of salinity stresses: 0, 70, 140 and 210 mM; four levels of Jasmonic Acid: 0, 50, 150 and 200 mM and three levels of humic acid: 0, 40 and 80 mM. The results showed that the effect of salinity on all the traits studied was significant except the ratio of the length of root and shoot. With an increase in salinity stress condition from 70 to 210 mM, there were 39% decrease in germination percentage, 55% in germination rate, 45% in fresh and dry weight, 30% in root length, 42% in shoot length, 37% in seedling length, 67% in longitudinal index and 61% in the weighted power, as compared with the control. However, the longitudinal power index increased. In addition, the use of jasmonic acid and humic acids had a significant effect on the traits studied. The interaction of the salt and hormones had a significant impact on plant fresh and dry weight, the length of the root, germination percentage, power weight index and average time needed for 50 percent germination. Given that the highest rate of root length and plant fresh and dry weight belonged to the interaction of humic and jasmonic acid in the absence of salinity, that in the presence of humic acid (with 80 mM concentration), Rosselle can bear salinity up to 140 mM and maintain stamina root length and that the germination rate of Rosselle increases by adding jasmonic acid up to 200 mM,  one can conclude that the interaction of jasmonic and humic acids not only improves germination rate, but it also contributes to root length because, with an increase in root length, Rosselle can bear water stress conditions.

Highlights:

1.  Jasmonic acid and humic acid increase the Rosselle germination in salinity condition.
2. Jasmonic acid and humic acid increase Rosselle the root length in salinity condition.

Extended abstract
Introduction: Pepper (Capsicum annum L.), which belongs to the solanaceae family, is one of the most important vegetable and garden products. Due to its nutritional value, its use tends to rise all over the world. Germination and seed emergence are strongly influenced by environmental stresses such as salinity and drought. Drought stress affects various aspects of plant growth. It reduces germination, delays vegetative growth and reduces dry matter in the plant. Salinity stress, as an environmental stress, is a limiting factor for the growth and development of crops and garden production.
Materials and Methods: The present study was conducted to evaluate the impact of drought and salinity stress on seed germination characteristics of sweet pepper (Capsicum annuum L.) in two separate experiments, using a completely randomized design with three replications in the Faculty of Agriculture, University of Birjand in 2016. PEG 6000 was used for drought stress and NaCl, for salinity stress. The treatments included drought and salinity stress levels (0, -2, -4, -6, -8, -10 and -12 bars). Seeds were disinfected with sodium hypochlorite (2%) solution for 1 minute, and were then washed with distilled water. The medium was petri dishes with a diameter of 9 cm.  25 seeds were placed on two layers of filter papers in each dish. 5 ml of distilled water or solution was added to each petri dish. The measured traits were germination percentage, germination rate, seed vigor index, radicle length, plumule length, ratio of radicle length to plumule length and dry weight of radical and plumule.
Results: The results indicated that salinity and drought stress had significant effects on seed germination characteristics of sweet pepper so that salinity stress with osmotic potential of -10 and -12 bar decreased the germination of sweet pepper and reached zero. Increasing salinity stress from zero to -12 bar decreased germination percentage, germination rate and seedling dry weight by 43.75, 41.67 and 93.46%, respectively. The results indicated that with increases in both salinity and drought stress, seed vigor index decreased significantly. The results showed that with increasing drought and salinity stress from 0 to -12 bar, seed vigor index decreased 96.58 and 100 percent, respectively.
Conclusions: The results of this study showed that the tolerance of sweet pepper to salinity stress was higher than its tolerance to drought stress at the germination stage, but for more accurate evaluation, it is necessary to conduct additional experiments in the field and in the greenhouse.
 
 
Highlights:
1- Investigation and comparison of germination and seedling growth of sweet peppers under salinity and drought stress.
2- Salinity and drought stress reduce germination indicators of Capsicum annuum.