Morpho-physiological Responses of Asparagus Accessions to Drought Stress Under Greenhouse Condition

Asparagus is a perennial plant which belongs to Asparagaceae family. Some of the most cultivated cultivars of asparagus are susceptible to abiotic stresses. Different species of asparagus plant are distributed in different regions of Iran which could be useful genetic resources to apply in breeding programs. The purpose of the current study was to evaluate drought tolerance rate of Iranian asparagus accessions and comparing their resistance rate with that of 'Mary Washington' commercial cultivar in order to introduce most tolerant accessions for future use in breeding projects. A factorial experiment based on a completely randomized design was performed to evaluate drought tolerance rate of nine Iranian asparagus accessions and 'Mary Washington' cultivar as control under greenhouse condition. The highest percentage of seed germination was recorded in Baladeh accession (71.66%) and this accession also showed the highest carotenoid content under drought stress conditions (0.43 mg g Fw(-1)). The percentage of electrolyte leakage in asparagus accessions increased by 69.98% under drought stress level of 25% FC comparing to control condition. Free proline content of asparagus accessions was affected by interaction between accession and drought stress. Gazanak was the superior accession in terms of free proline content under highest applied level of drought stress (4.5 mu mol g Fw(-1)). Baladeh and Gazanak could be introduced as drought tolerant asparagus accessions. Harsh environmental conditions of distribution areas and high ploidy level of these accessions could be considered as main reasons for their high drought tolerance rates.