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Development and Testing of a Tractor-mounted Positioner for Mango Harvesting
R.A. Gupta，R.M. Satasiya
Pramod Mohnot ，N.K. Gontia
Abstract
In order to reduce losses sustained during harvesting of mango and to maintain fruit quality, a tractor- mounted positioner was developed and tested for mango harvesting at the Sagadividi farm of the Gujarat Agricultural University, Junagadh Campus. During operation, it was observed that using the positioner for harvesting, only the mature fruits with stalk of 10-20 mm length with out sap bums and any other damage to the fruits, could be harvested. White layer (bloom), which is desir able from quality point of view, was also maintained. Though the work output was slightly reduced over all economics was in favour of the use of the positioner for harvesting as compared to the traditional picker. Using a positioner in orchards can save about Rs. 1,000 per tree in a good season.
Introduction
Mango (Manaifera indica),、the “king” of fruits, has prime impor tance among the commercial fruits grown in India-the largest producer and exporter of mango in the world. In Gujarat about 382 thousand tonnes of mango is produced annu ally over an area of 57 thousand hectare (Data book 2000). Gujarat produces export quality of mango mainly the Alphonso and Kesar va rieties. The latter has excellent quality for export and grown almost throughout the state, concentrating in South Gujarat and Saurashtra. The quality of the fruits mainly de pends on their maturity stages , har vest and post harvest techniques adopted by the mango growers.
Harvesting of fruits in India is mostly done manually by means of a curved knife, pair of scissors or blades attached to a hanging basket to the distal end of bamboo sticks (Devnani, 1980). For harvesting mango, hand picking manually op erated low capacity gadgets and tree shaking methods prevaile which re sults in high labour and energy re quirements, drudgery, damaged fruits, damage to tree branches etc. The damage and bruising are very serious problem. The fruits should not be allowed to fall on the ground as the injured fruits cause spoilage to other healthy fruits during pack aging and storage. Fruits harvested with 8-10 mm long stalks appear better on ripening as undesired spots on the skin caused by sap bum are prevented. Such fruits are less prone to stem — end and rot and other stor age diseases (Sapovadia et. al. 2001).
RTTC, Jurhat, Assam (1988) worked on fruit harvesting devic es. The manually operated unit worked on the principle of individ ual fruit cutting by sickle / blade and collecting the fruit in a bag. The unit was found suitable for av erage size and big fruits, which would be damaged if allowed to fall freely on the ground. The other unit worked on the principle of me chanical shaking of tree. This unit was suitable for hard fruits. Brown and Schertz (1967) also worked on mechanically operated harvesters and reported that fruits harvested by mechanical shaking have more in juries in the form of splits, internal and external bruising and superfi cial peel scars than manually har vested fruits.
RTTC, Gujarat Agricultural Uni versity, developed an improved picker and it showed better perfor mance as compared to other pickers collected from various centres of the country. About 90% of the fruits could be harvested with stalk of 10-20 mm in length, which is most desirable specifically for ex port quality of fruit. Fruits should be harvested manually using me chanical aids like a positioner on which a person can stand and pick the fruit using a pair of scissors / secateure. As the fruits are picked form very close distance hence, only mature fruits are harvested without any damage. Hence, keep ing the foregoings in view, a study for developing and testing of a trac- tor-driven and hydraulically operat ed positioner was undertaken at the centre.
Material and Methods
Prior to the design of the ma chine some preliminary informa tion regarding the tree characteristics were studied to en sure that the movability of the ma chine in the field, distribution of fruits within the tree and the per centage of fruits that can be har vested are estimated (Tables 1 to 3). The height of the machine and size of the cage were likewise studied. Using the above information a hy- draulically-operated positioner for harvesting mango and other fruits, was designed and developed. The safety factors were also taken into consideration. The cost of the ma chine was kept minimum by reduc ing the number of moving components in the design of the machine.
The machine consists of a frame, three-point linkage, hydraulic jack, supporting links,, extension pipe and cage. The frame of the ma chine is fabricated from angle iron of (50 × 50 × 6) mm size. The di mensions and structural members of the frame are shown in the Fig. 1. A hydraulic jack of 2 tonnes ca pacity with two cylinders is mount ed at the centre of the frame with the help of a pin of 40 mm passing through two plates welded to the frame and lower end of the hydrau lic jack. The upper end of the jack is supported by fastening three sup ports to the frame and upper end of the jack. Similarly, the upper end of the piston is fastened to a flange through nuts and bolts. To extend the height of the positioner an ex tension pipe of 100 mm and 1 m length is attached to the upper end of the piston through flange, nuts and bolts. On the upper end of the extension pipe another flange of the same size (20 × 20) cm is welded on which cage is fixed through nuts and bolts. The cage of machine is fabricated from angle iron, mild steel flat and wood. The frame of the cage is made out of angle iron. The size of the cage is (92 × 76 × 70) cm. At the bottom of the cage, wooden plank is provided. On one side of the bottom an opening of (55 ×47) cm size is provided through which an operator can get on the positioner to pick up the ma ture fruits. All the four sides of the positioner are kept folding so that when the machine is on transport from one place to another the sides can be lowered to keep the height minimum.
To operate the machine, it is hitched to a tractor through three point linkages and hosepipe of the hydraulic jack is connected to the hydraulic system of the tractor. The cage is mounted on top of the ex- tens4?n piece and its sides are fold ed. The machine is transported to the orchard where mango picking is to be done. During operation, the machine is placed on ground and operator gets on the cage along with a pair of scissor and carton through the opening provided at the bottom of the cage. All the sides of the cage are kept in upright position and hinged to the frame through hooks pins for safety point of view. The hydraulic system of the tractor is operated to lift the cage. As soon as the valve is opened, the oil under pressure goes to jack through hosepipe, which lifts the piston of the jack, thus, the cage is lifted. When required height is reached, valve is closed to stop further upward movement of the cage. Then, the operator pick the fruits from a very close distance using a pair of scissors / secateure. Only matured fruits are picked and kept in the carton.When the carton is full of fruits it is packed and taken on the ground. The machine is taken around the tree to pickup matured fruits. Some of the fruitswhich are located on the top of the tree, are beyond the reach of the operator, are picked using manually operated mango picker.
Fig. 1 Tractor-mounted positioner for harvesting mango.
Fig. 2 Positioner attached with power
Fig. 3 Operator picking mango using positioner.
Testing
A field testing of the machine was conducted at the Sagdividi farm of Gujarat Agricultural University, Junagadh campus for the Kesar variety of mango which is very popular among in the Saurashtra region of Gujarat state. The
trees were planted at (12 X 12)m distance. HMT zetor tractor of 35 hp was used to operate the machine. An experienced worker was engaged to pick the fruits in standing posture on the positioner. During testing of the machine some important observations like number of fruits harvested / h, weight of fruit harvested / h, average stem length (mm), visible damage (%), physiological loss of weight (%),
shelf life of fruits (days) etc. were recorded.
The cost of harvesting was determined out considering the prevailing rates of the tractor and labour during the season. Two workers,one for picking the fruits and another to receive the harvested fruits,were required for the operation.The experienced worker is engaged in picking the fruits and was paid better than the less experienced worker. The same workers were used to harvest the fruits using the developed machine.
In order to estimate physiological loss in weight (PLW) of the har vested fruits two plastic trays lined with newspapers, were kept on the table at room temperature (20°) and the harvested fruits were arranged in these trays in line keeping the stem end upward. The weight of the fruits was recorded every three days. On the 7th day, few fruits har vested using traditional picker showed symptoms of deterioration， are removed from the tray.
Fig. 4 Fruit packet being taken from the positioner.
Fig. 5 Operator picking coconut using positione
Fig. 6 Fruits harvested using traditional mango picker.
Fig. 7 Fruits harvested using developed positioner.
Results and Discussion
(i) Harvesting capacity
The results recorded during the trial of the machine are shown in Table 4. The average number of fruits harvested using the positioner were 360 per hour compared with local mango picker which can pick an average of 377 fruits per hour. Thus, using the positioner the har vesting capacity of the operator was slightly reduced. Considering that in raising / lowering and shifting the positioner took more time. Similar results were reported by Schertz (1967). During his study he observed that an operator stand ing on the ground was more effi cient than harvesting the fruits from a ladder / positioner.
(ii) Stem length
The stem length is one of the most desirable parameter’，The stem length of the stem fruits har vested using the positioner was within 20 mm. and uniform while in fruits harvested with traditional picker, had stems more than 50 mm and non-uniform. A number of fruits were harvested without stem, which is not desirable from the quality point of view. Such fruits do not have good appearance and a mango grower has to sell them at lower prices in the market. More over, it has been reported that fruits harvested without stem are subject to the occurrence of stem end rot disease. Fruits with stems recorded delayed ripening. It is necessary that the fruits should have stems ranging from 10 to 20 mm.
(iii) Visible damage
Visible damage on the fruit was observed in the form of sap burns. The fruits harvested without stem had sap bums. Such type of dam age was almost nil in fruits harvest ed using the positioner because all the fruits had stem while the fruits picked using the traditional picker shows 11.11% visible damage.
(iv) Shelf life of fruits
This refers to the life of fruits in days for which they can be stored after harvesting without sustaining spoilage. The shelf life is affected by the harvesting methods. Fruits harvested using the positioner could be stored for 9 days without show ing symptoms of spoilage. The ap pearance of the fruits was good and had attractive color. In comparison, those harvested using the traditional picker should dark spots on the body on the 7th day from the date of harvesting. If the fruit is physically damaged or injured the respiration rate of the fruit is increased and it is prone to microbial attack hence, during handling of the mango fruit, care taken to avoid any kind of inju ry and increase the shelf life of the fruits.
(v) Cost of harvesting
As indicated in the Table 4 the cost of harvesting for using the po sitioner was Rs. 2783 / tonne of mango fruit as compared to Rs. 368 / tonne using the traditional picker. Thus, the cost of operation for the former was high but the quality of harvested fruit was very good and not a single fruit was lost by way of spoilage or decay while 10 -15%
fruit loss was observed in case of traditional picker. Hence, consider ing 10% loss out of every 1000 kg. only 900 kg. of fruits were avail able for sale. That too at lower rate (Rs. 17.50 / kg') amounting Rs. 15,750. The fruit harvested using the positioner could be sold at high er price (Rs. 20 / kg.) amounting Rs. 20,000, thus gaining Rs. 4,250 more as compared to using the local picker. Subtracting the extra oper ating cost required in the case of the positioner i.e., Rs. 2,415 a net profit of Rs. 1835 / tonne could be har vested by a mango grower. In other words, about Rs. 900 / tree can be saved by adopting the developed positioner for harvesting of mango.
(vi) Physiological loss in weight
Observations regarding the phys iological loss in weight (PLW) were also recorded every three days in the laboratory for each method of fruit harvesting in percentage and presented in Table 5. The PLW was higher on 3rd, 6th and 9th day for the fruits picked using the traditional mango picker. The total PLW was 13.27% and 15.88% for fruit har vested with the positioner and tradi tional picker, respectively.
Fig. 8 Tractor mounted positioner.
Conclusions
From the study following conclu sions can be drawn:
Using the positioner, mangoes without any mechanical injury are picked and only matured fruits are harvested as operation is conducted at a close distance.
As 100 percent fruits are harvest ed with stems (1-2 cm), no sap bums were found and white layer (bloom) on the fruit is also main tained.
Loss of fruit during storage and transportation is minimized.
Due to high quality of fruit main tained during harvesting an fruit grower can harvest a net sum of Rs. 1000 per tree in a good season.
REFERENCES
Annual report, 2000. Research, Testing and Training Centre, Gujarat Agricultural university, Junagadh Campus, Gujarat.
Brown and Schertz, 1967. Princi ples and practices for harvesting and handling of fruits and nuts, vol.
Data book (1992-99). Director of Horticulture, Gujarat State, Ahmedabad. Bulletin No. 20 / 2000 p. 8.
Devnani, R.S. 1980. Harvesting equipments developed in India. Technical bulletin No. CIAE / 78 / 8，CIAE, Bhopal
SapovadiaB.D., Patel H.N., Gupta R.A. and Pund S.K., 2001. Design and development of mango harvesting device. AMA30(l): 31-34.