Mechanised Moriculture Production System

Although, mulberry plants are grown in Australia as ornamentals or fruit, there are no data available or work done to assist in establishing a sericulture industry. This research conducted in Lockyer Valley in South East Queensland covered four areas of mulberry leaf production in identifying mulberry varieties and practices suitable for Australian conditions. The first trial involved identifying local mulberry varieties with desirable characters of high leaf yield, high protein content, high carbohydrate content and high moisture content; these are the characters desirable for sericulture production. Nine mulberry varieties consisting of Morus nigra, Morus alba and Morus macroura cv. Shahtoot, were identified as planting material in South East Queensland. Cuttings were raised in polybags in a glasshouse for 18 weeks. The plants of nine varieties (LV1 to LV9) were transplanted into the field on raised plastic mulch beds at a row by tree spacing of 4 m × 2 m. A randomised block design and three replications was used. Irrigation and fertiliser were applied through a drip system. Three sets of data were recorded over the trial period. Harvest 1 was taken at 20 weeks after transplanting, Harvest 2 at 13 weeks after first pruning and Harvest 3 at 30 weeks after second pruning. The characters evaluated were leaf and shoot yield (fresh and dry weight), crude protein and carbohydrate (TNC) content, moisture content, growth rate, number of shoots, number of branches, stem diameter, longest shoot height, internode length, leaf size and shape, number of leaf lobe and 20 leaf weight. The number of branches, stem diameter, longest shoot height, internode length were measured on the longest shoot at harvest. Using Harvest 2 data, when leaves are normally harvested and fed to silkworms, varieties, LV5 and LV7, recorded higher fresh leaf yields (2.13 t/ha and 2.21 t/ha respectively), leaf moisture content (60% and 59%), and intermediate carbohydrate content (17.5% and 14.9%). Although both varieties, LV5 and LV7, recorded low protein contents (13.6% and 15.7% respectively), they were recommended for sericulture production based on overall performance. LV9, at Harvest 3 recorded high fresh leaf yield (5.6 t/ha), protein content (18.6%), carbohydrate content (12.5%) and moisture content (65%), therefore it was also recommended for sericulture production. The second trial involved five varieties Morus alba sp. (MA), Morus nigra sp. cathayana, Morus nigra sp. kanva (MK), Morus nigra sp. multicaulis (MM) and Morus nigra sp. (MN) imported from Indonesia. The trial set up, data collection and analysis were the same as in the first trial. Two sets of data, Harvests 1 and 2, were recorded over the research period. Varieties, MM, MK and MC were recommended for silkworm feeding based on leaf yield, protein content, carbohydrate content and moisture content. MM recorded the highest leaf yield (6.57 and 8.13 t/ha), followed by MK (3.66 and 4.79 t/ha) and then MC (3.43 and 4.54 t/ha) for Harvests 1 and 2. Moisture content for MM (68% and 75.1%), MK (71% and 77.5%) and MC (71% and 76.2%) were high at both harvests except for MM (68%) which recorded the lowest at Harvest 1. MM (17.5% and 15.5%) recorded the lowest at both harvests for protein content, whereas MK (17.8% and 18.9%) and MC (17.6% and 18.9%) maintained intermediate protein contents at both harvests. MK (18.1% and 15.5%) recorded the highest carbohydrate at both harvests while MM, in general, recorded intermediate carbohydrate contents. MC recorded intermediate and lowest carbohydrate content (13.8% and 12.7%) at Harvests 1 and 2 respectively. In general, MM, MK and MC showed characters which were higher than MA and MN, although MM recorded low protein content. The third trial looked at the effect of plant density on the main economic characters of mulberry plants. A local variety, LV1, was planted using six density treatments of row x plant spacing 0.6 m x 0.5 m, 0.6 m x 1.0 m, 0.6 m x 1.5 m, 4.0 m x 0.5 m, 4.0 m x 1.0 m, 4.0 m x 1.5 m using a strip plot design. Two sets of readings were measured over the research period. Harvest 1 occurred at 26 weeks after first pruning and Harvest 2 at 37 weeks after the second pruning. The 4.0 m x 0.5 m spacing treatment (5,000 plants/ha) was recommended for sericulture practice because leaf yield was high (2541 kg/ha and 4274 kg/ha) at Harvests 1 and 2, protein content was highest (19.7% and 19.1%) at both harvests, carbohydrate content was lowest (14.1%) but second highest (20.2%) at Harvest 1 and 2 respectively. Moisture content was highest (59.9%) and low (61.4%) at Harvests 1 and 2. The fourth area of study involved designing, developing and testing a mechanical mulberry leaf harvester. The harvester consisted of a reel, reciprocating cutting knife, conveyor, hydraulic system, lift mast, collection bin and support frames. The harvester was supported at the tractors three point linkage and operated by the tractors hydraulics. The harvester was field tested on 14 and 20 week mulberry plants, planted at 1 m apart and at row spacing of 4 m. Harvesting operations were performed at three tractor forward speeds (1.5, 2.0 and 3.0 km/h) in combination with reel, cutting knife and conveyor speeds. It was observed that all mulberry plants within the effective cutting area (100% cutting efficiency) were harvested at the three forward speeds. The collected yield ranged from 0.63 t/ha to 2.25 t/ha, collection efficiency ranged from 65% to 93% and damaged shoots ranged from 9% to 34%. New shoots budded and grew from all the harvested shoots (damaged and undamaged). The four trials showed that local varieties LV5, LV7, and LV9 together with imported varieties MC, MK and MM produced high leaf yield, protein, carbohydrate and moisture content. A 4 m x 0.5 m spacing (5000 trees/ha) treatment showed high values for the desirable characters, therefore the six high production varieties as well as the 4 m x 0.5 m spacing arrangement are recommended for sericulture production in Australia. Also the mechanical leaf harvester which showed satisfactory performance can be utilised to minimise labour costs