Studies on engineering properties of multiplier onion

The knowledge of physical and mechanical properties of onion bulb is important for successful design of any planter. Multiplier onion is propagated through bulbs and bulbs are planted manually. Manual planting of onion bulb is highly labour intensive (80-100 man-days ha-1) due to the close plant geometry (plant to plant and row to row spacing is 10 × 15 cm) among the vegetable crops. Engineering properties of multiplier onion were determined in order to design and develop a tractor operated raised bed onion bulb planter. In multiplier onion each onion comprises of 4-5 bulbs. These bulbs were cleaned, separated into single bulbs and divided in to 9 categories manually based on their individual weight viz., <2g, 2-3 g, 3-4 g, 4-5 g, 5-6 g, 6-7 g, 7-8 g, 8-9 g, >9 g. The onion bulb had a moisture content of 80.62±0.87 %. It was observed that the properties varied for different sizes of onion grades and the grades had highly significant effect on most of the properties. The linear dimensions of onion bulbs viz., length, width, thickness for nine grades ranged from 21.21±2.60 to 32.31±3.30 mm, 13.54±1.77 to 30.95±2.91 mm and 10.91±1.40 to 22.63±2.15 mm. The geometric mean diameter, sphericity, shape index and projected area all ranged from 28.22±2.04 to 14.54±0.96 mm, 0.87±0.06 to 0.69±0.08, 1.78±0.32 to 1.22±0.14 and 5.50±0.51 to 1.55±0.30 cm2, respectively. The one hundred onion bulb weight, bulk density, true density were in the range of 1185±19.59 to 121.6±6.30 g, 793.20± 9.45 to 480.19±13.13 kg.m-3, 1086± 205.22 to 1013.6±348.85 kg.m-3, respectively. The angle of repose decreased with increase in size of onion bulbs. The interaction between sphericity, shape index and angle of repose indicated that as the size of the onion size increase angle of repose decreased.

Engineering Properties of Peeled and Unpeeled Multiplier Onion

Multiplier onion (Allium cepa L. var aggregatum. Don.) is mainly used for its unique flavour in seasoning dishes. The unpeeled onions are processed at farm level by means of primary processing and by secondary processing various products like paste, flakes, powder could be produced from peeled onions. For the design of processing and handling equipment knowledge of engineering properties is essential. The engineering properties of peeled and unpeeled multiplier onion were determined. The average values of the physical properties of unpeeled onion were recorded for bulk density and true density as 636.621 and 1526.825 kg/m3 respectively. Similarly for peeled onions, the bulk and true density were 627.03 and 1108.74 kg/m3 respectively. The moisture present in peeled and unpeeled onion was 77.66 % and 74.43% (w.b) respectively. The TSS of multiplier onion was found to be 20° Brix for both peeled and unpeeled samples. The colour values were also measured using colour flex meter for the peeled and unpeeled onions. The frictional properties including coefficient of friction, filling and emptying angle of repose were also measured. Mechanical properties were determined by using a texture analyser. The firmness was measured in terms of penetrating force and crushing strength which were recorded to be 8.59 N and 124.93 N respectively for peeled and 12.00 N and 138.35 N respectively for unpeeled onions.

Standardization of organic protocols for growth and seed yield of multiplier onion (Allium cepa var. aggregatum) cv. Co (On 5)

Afield experiment on Effect of organic manures and biostimulants on growth and seed yield of multiplier onion (Allium cepa var. aggregatum) cv. Co (On 5) was conducted at Agricultural Research Station, Vaigaidam. The experiment was laid out in a Factorial Randomized Block Design with two factors viz., organic manures and biostimulants which includes M1- Control, M2- FYM (12.5 t ha-1), M3- Neem cake (2 t ha-1) and M4- Vermicompost (2 t ha-1) and S1- Control (water spray), S2- Humic acid (0.2 %), S3- Panchagavya (2%), S4- Vermiwash (2%) and S5- Seaweed extract (2%). Totally twenty treatments and were replicated thrice. The results revealed that soil application of FYM @ 12.5 t ha-1 recorded higher plant growth bulb yield and seed yield when compared to other organic manures of the present study. Similarly among the bio stimulants 2 per cent seaweed extract spray recorded higher plant growth, bulb yield and seed yield when compared to other bio stimulants of the present study. Interaction effect also showed that soil application of FYM @ 12.5 t ha-1 and foliar application of seaweed extract excelled and recoded the maximum plant growth, bulb yield and seed yield in multiplier onion.

Effect of Different Planting Orientation of Onion Bulbs on Growth Parameters Relevant to Development of Raised Bed Onion Bulb Planter

Multiplier onion is among the four groups of onions classified by horticulturists which is propagated through bulbs. Presently onion bulb planting is done manually by planting the root portion oriented downwards as pressed into an irrigated field. Generally about 80-100 man days are required to plant one hectare of onion at a spacing of 15 cm by 10 cm. The manual planting is labour intensive, highly drudgery involved and time consuming. There is need to develop an onion bulb planter possibly with four orientations. Therefore, an experiment was carried at ICAR-Indian Institute of Horticultural Research, Bengaluru to study the effect of different planting orientations of onion bulb on growth parameter. Onion bulbs were planted on raised bed 45 m long and 0.9 m width at 15 cm row spacing and 10 cm in-row spacing. The four treatments used were viz., T1) root portion up, T2) root portion down, T3) horizontal and T4) inclined. Experiment was laid as a randomized block design with 5 replications. The growth parameters namely i) germination percentage at 7th and 15th days after planting, (DAP), ii) Plant height 15th and 30th DAP and yield. The results showed that the growth parameters were on par in all the three treatments (root portion down, horizontal and inclined) except in treatment root portion up.