Effects of seedling age and rates of phosphorus fertilizer on growth and yield performance of onion (Allium cepa L.) under irrigation at Alage, Central Rift Valley of Ethiopia

Abstract

Onion is an important cultivated crop as a condiment as well as a source of income for many farmers in Ethiopia. However, the productivity of the crop is much lower due to different problems. A field experiment was conducted to determine the effect of seedling age and phosphorus rate on growth and yield performance of onion at Alage, Central Rift Valley of Ethiopia, during 2016/2017 season. The treatments comprised three seedling ages (6, 7 and 8 weeks of seedling age) and four phosphorus rates (0, 46, 92 and 138 kg P 2 O 5 ha-1). The experiment was laid out in randomized complete block design (RCBD) with four replications. The result showed that seedling age and phosphorus rate significantly affected plant height, leaf length, days to maturity, fresh bulb weight, bulb dry matter fraction, bulb length, marketable bulb yield, total bulb yield, and harvest index. Among these parameters, marketable bulb yield, total bulb yield and harvest index were also significantly affected by the interaction of seedling age and phosphorus rate. On the other hand, leaf number per plant, bulb diameter, total biomass yield and unmarketable bulb yield were only influenced by the effect of phosphorus rates. In this study, transplanting at 8 weeks of seedling age fertilized with 138 kg P 2 O 5 ha-1 recorded the highest total bulb yield (50.6 t ha-1) and marketable bulb yield (48.33 t ha-1), but no significant difference was shown with that obtained at 92 kg P 2 O 5 ha-1 with the same seedling age. Treatment combinations of seedling age at 6 weeks and no P (control) produced the lowest amounts of total bulb yield (24.27 t ha-1) and marketable bulb yield (21.63 t ha-1). The partial budget analysis revealed that the highest net benefit with low cost of production was obtained in response to the application of 92 kg P 2 O 5 ha-1 and the transplanting age of 8 weeks. The marginal rate of return for this treatment was 5657% which is found to be economically feasible for producing onion in the study area.

Influences of Seedling Age and Variety on the Growth and Bulb Yield of Onion in Northwest Ethiopia

“…Infuenced by Variety and Seedling Age of Onion Ethiopia [22], which is in line with the results of the present study. Early related to 60 days old seedlings of onion observed in the present study could be associated with less transplanting shock and lag time and thus continuation of photosynthesis activities after transplanting and accumulation of assimilates in the bulbs that hasten maturity [23].…”

“…Hardened, healthy, and uniform seedlings were transplanted on the well-prepared experimental feld on the same date where onion seedlings were 30, 40, 50, and 60 days old after sowing. Planting of onion seedlings was conducted using ridge planting system in double row (Figure 3) with the recommended spacing 40 cm between water furrow, 20 cm between rows, and 10 cm between plants within row [13]. A plot consisted of four double rows and two single rows at each side of the plot where one row contained 15 onion plants.…”

“…Although genetically and morphological diferent, all onion varieties released by Agricultural Research Centers are transplanted at the ages ranging from 40 to 50 days in Ethiopia [12]. On the other hand, seedling ages of vegetables including onion infuence the growth and development of the crop as indicated by Anbes et al [13]. In the feld trial conducted by Muhammad et al [14], onion seedlings transplanted at 40 days after sowing produced the highest plant height, leaf number, leaf length, size and weight of bulbs, and bulb yield as compared to seedlings with the age of 50 and 60 days.…”

Growth and Yield of Shallot (Allium cepa L. Aggregatum Group) with Application of Amino Acid Biostimulant Dosages

“…P is a necessary nutrient that plays an aspect in the preparation of adenosine diphosphate (ADP), adenosine triphosphate (ATP), deoxyribonucleic acid (DNA), and ribonucleic acid (RNA). Furthermore, P can stimulate root growth, strengthen stems, and increase onion bulbs' weight and size (Anbes et al, 2018). According to Khan et al (2019), spraying individual amino acids improved the uptake of N (67.44%), P (66.57%), and K (50.55%) and the yield of lettuce.…”