Investigation of warehouse temperature and initial standard germination on germination factors and enzymatic activities in two onion (Allium cepa L.) seed cultivars

This experiment was conducted to evaluation of warehouse temperature effects on two cultivars of onion (Alba and Texas early grano؟) with different initial standard germination. In these, study three levels of initial standard germination including 1- 70-75% 2- 80-85% and 3- 90-95% of two onion cultivars including: Alba (long day) and Texas early grano؟ (short day) were selected. Seeds stored in tow conditions including  5 ºc and 60% relative humidity  and 25 ºc and 30% relative humidity. The study carried out as a factorial experiment based on a completely randomized design in four replications.  After storage period, germination %, normal seedling%, mean time to germination (MTG), rate and percentage of emergence seedlings catalase and peroxidase activities were measured. Factors were initial standard germination levels in three levels, warehouse temperatures in two levels and cultivars in two levels. Results showed that interaction of temperature  initial standard germination  cultivar had significant effect on germination, MTG, percentage and rate of seedling emergence. In addition, interaction of initial standard germination  cultivar and interaction of temperature  initial standard germination on normal seedling were significant. Mean comparisons showed that germination percentage of Texas early grano Cultivar with 90-95% initial standard germination when stored at 5 ºc warehouse temperature was higher than 25 ºc warehouse temperature significantly. Generally, in all three levels germination, normal seedling percentage was decreased with increasing of warehouse temperature. The highest MTG belonged to Texas early grano in both warehouse temperatures (5 and 25 º c) with 70-75%, initial standard germination. The lowest one belonged to Alba cultivar with 90-95% initial standard germination and Texas early grano with 80-85% initial standard germination when stored at 5ºc. In Texas early grano, seeds with 90-95% initial standard germination and 5ºc temperature warehouse had higher establishment than 25 ºc. Based on the results, storage conditions can affect germination and seedling emergence by affecting enzymatic activity.