The effect of planting date and mother bulb size on seed quality and quantity of (Allium cepa) Texas Early Grano 502 onion variety in Frieden, Esfahan

The selection of optimum planting date for every climate and mother bulb size are important factors affecting the quantity and quality of seed production in different cultivars. This study was performed in Isfahan province, Frieden, during two growing years 2016-2017 to determine the effect of planting time and mother bulb size on the quantity and quality of short-day onion seed varieties Texas Early Grano 502

A split-plot experiment was performed in a randomized complete block design with four replications. The main factor was cultivation dates at four levels: the end of August, the first of September, the end of September and the first of October and mother bulb size at three levels with 3.55, 5.5-7, and 7.5-9cm diameters were assigned as sub-plots. The measured traits were number of umbel per unit area, the number of fertilized capsules in umbel, the number of seeds per capsule, 1000 seed weight, seed yield and germination rate.

The results of combined analysis of variance showed that effect of year was only significant on the number of capsules per umbel at p<0.01. The interactions of year× mother bulb diameter and year× planting date× mother bulb diameter were not significant for any of the traits. The traits were not affected by the year. The results showed that the planting date had a significant effect on all traits except for 1000 seed weight, and the first planting date (the end of August) had the highest values in all traits. The highest germination percentage (89.83%) and the highest germination rate (12.8) were obtained on the first planting date, which showed a statistically significant difference with the subsequent planting dates. However, these two traits were not affected by mother bulb diameter treatment. The highest seed yield for onion diameter factor (505.65 kg h-1in the first year and 465.78 kg h-1 in the second year) was associated with mother bulb size of 7.5-9 cm.

The overall result showed that to obtain the highest and most desirable quality of onion seeds of Texas Early Grano 502 cultivar in Friedan of Isfahan, the planting date of the first of September and the size of the mother bulb “between” 7 to 9 cm is recommended.

Highlights:

1- Early planting time (the first of September) increased germination rate.
2- Increasing the mother bulb size increased the onion yield.