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Thesis (M.Sc. (Plant Production)) -- University of Limpopo, 2014 / Wild medlar (Vangueria infausta subsp. infausta) is a popular indigenous fruit available and consumed by rural communities in Limpopo Province, South Africa. Inadequate post-harvest practices in indigenous fruit plants including V. infausta fruit forms major constrains in expanding their production. There is scanty information documented on neither objective nor subjective harvesting indices of indigenous fruit plants consumed by locals in sub-Saharan Africa. Thus, the objective of this study was to determine the effect of harvesting time on physico-chemical properties and selected nutritional composition of V. infausta fruit. Fruits were harvested twice, where two harvesting times were regarded as treatments and each tree as replication. The reduction for fruit weight, sugar content and sugar/acid ratio was highly significant (P ≤ 0.05), whereas for average fruit diameter, seed weight, acid ratio and pH content this may imply that the listed parameters are treatment which was non-significant (P ≤ 0.05). The treatment reduced P, K, Mn and Fe by 33%, 18%, 3% and 7%, respectively. On the other hand, treatments had no effect on N and Ca. The reduction of phosphorus was highly significant (P ≤ 0.05), whereas for N, K, Ca, Mn and Fe treatment impact was non-significant (P ≤ 0.05). Similarly, the treatment consistently reduced moisture content and increased dry matter and crude protein of V. infausta by 76%, 300% and 7%, respectively. The reduction of moisture content, increase in dry matter was highly significant (P ≤ 0.05), whereas crude protein treatment impact was non-significant (P ≤ 0.05). The data indicated that the best time to harvest V. infausta fruit was during January when fruits were cosmetically appealing and not wrinkled. This study demonstrated that there was less variation in some measured objective harvesting indices of V. infausta fruit harvested at two harvesting time. More work would be required to do physico-chemical properties and selected mineral elements analysis from wide growth habitat for conclusive recommendations.

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A pneumatic harvesting method for jojoba seed was investigated. By constructing a stationary experimental unit, the motion of jojoba seeds and stones, which were close in size and weight to seeds, were examined under the effect of positive, negative, and a combination of both pressures. It was determined that there was a reasonable difference in the motion depending upon test conditions and head design. A vacuum head was designed based on the observations and data obtained from the experiments. Using this head it was possible to pick up jojoba seed without picking up stones. A nonstationary unit was constructed to examine the effect of ground speed on picking efficiency. Results showed that a cleaner harvest using a normal ground speed can be obtained with the new head than with conventional equipment. A blowing head was added to windrow seeds and increase the capacity of the machine. It was determined that when the two heads were used together harvesting field capacity increased, however reduced efficiency was found.

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University of Macau / Faculty of Science and Technology. / Department of Electrical and Computer Engineering

At its peak, Oregon produced 21 percent of the nation's total commercial strawberry production. However, since 1971, Oregon's share of strawberry production has been declining steadily. In fact, for the last three years strawberry production in Oregon constitutes only 8 percent of the nation's total production, which is the lowest since the end of the Korean War (Figure 1). Among other factors, the increase in harvest cost without an offsetting increase in the farm prices of strawberries, is the main cause for the continuing decline of strawberry production in Oregon. Decrease in the supply of strawberry pickers is the main cause for the upward trend of the strawberry harvest cost in Oregon. Particularly, since 1973, due to enactment of the child labor law, the shortage in the supply of strawberry pickers in Oregon has intensified, causing further escalation in harvest cost. Thus, in order to alleviate the problems associated with harvest cost, since 1967, Oregon has been actively seeking to mechanize its strawberry harvest. The principal objective of this thesis has been to evaluate the economic feasibility of mechanical strawberry harvest in Oregon. As demonstrated in Chapter V, depending on the assumptions about the quality and the average yield of the strawberry varieties that would eventually be harvested mechanically, and the efficiency of the harvester; the expected savings per acre to the strawberry growers from the use of mechanical harvester was shown to range from a net saving of $523.50 to a net loss of $186.76 (Table 9). Even though negative savings are shown to appear when extremely unfavorable conditions are assumed, in the majority of cases discussed in Chapter V, the implementation of mechanical strawberry harvesting in Oregon is found to be associated with significant positive returns to the growers. In addition, in Chapter VI, under certain conditions which are expected to prevail if mechanization of strawberry harvest become a reality in Oregon, the annual gross and net 'social rate of returns' were estimated to be 330 percent and 95.7 percent respectively. The difference between the gross and net social rate of return is the wage loss of the displaced workers. Based on the above social return figures and the estimated savings to the growers, it appears that mechanical strawberry harvesting is an economically viable alternative that could eventually solve the problem of the growing shortage of strawberry pickers in Oregon. / Graduation date: 1978