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Technical annual report 2000-01



Technical annual report 2000-01


Dept. of Regional Development, Primary Industry, Fisheries and Resources technical annual report; Department of Regional Development, Primary Industry, Fisheries and Resources technical and annual report; Reports; PublicationNT; Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295




Made available via the Publications (Legal Deposit) Act 2004 (NT).






Agriculture -- Northern Territory -- Periodicals; Fisheries -- Northern Territory -- Periodicals

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Dept. of Primary Industry and Fisheries

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Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295



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Technical Annual Report 2000/01 131 standard level. Calcium levels, however, were similar for each of the treatments, but below the standard level. Potassium levels were similar for all treatments, and within the standard range for all treatments. Similar results are shown for magnesium levels. Phosphorus levels were all below the respective standard level, but tended to decrease with an increased number of cuts. Boron levels were similar for all treatments and within the standard range. Zinc levels were similar but below the standard level for all treatments. Table 1. Effect of root pruning on photosynthesis rates Treatments Treatment 1 2 cuts in December Treatment 2 4 cuts in December Treatment 3 2 cuts in April Treatment 4 4 cuts in April Treatment 5 pruning Photosynthesis rate 7.2 4.7 6.5 4.7 8.5 The above results show that root pruning can substantially reduce vegetative growth, if done early in the growth season, and subsequently lead to increased yields compared to non root pruned trees. Nevertheless, the results also show that imposing a root pruning treatment after the growth season can also lead to increased yields. These findings are similar to a trial reported on earlier in which much larger trees were subjected to the same treatments. However, we did not measure photosynthesis in that previous study, but the result shows here that perhaps with the production of increased carbohydrate levels in root pruned trees photosynthesis is shut down temporarily. As one would expect photosynthesis would certainly contribute to the yielding capacity of the tree. The above findings suggest that certain root pruning treatments may allow trees to assimilate and distribute assimilates more efficiently than non- root pruned trees. When this project concludes, more detailed results will be provided. PROJECT: Improvement of Mango Productivity - Project in Katherine Project Officers: J. Mansfield, T. Maddern, C. Kinnaird and R. Renfree Location: Co-operators' properties in the Katherine Region Objective: To increase regular, early and profuse flowering and fruiting in Kensington Pride mango in the NT. To develop a high density planting system as an option for NT conditions. Adoption of complete management systems for optimum sustainable production for the 2002 mango season by the majority of industry. There are large variations in yield and fruit quality between two different mango farms in the same year, between trees on the same farm in the same year, and on the same tree in two consecutive years. To try to understand this variation, a previous study in the Katherine Region investigated 12 groups of three trees in orchards on three different soil types over three years. These orchards varied in management practices and in the bearing age of the trees. Information was collected on the nutrient status of the leaves at flowering and after harvest, fruit yield and fruit quality. However few relationships between yield and the concentration of nutrients were observed. This possibly was because soil type, climate, microclimate, rootstock and management practices may have had a greater impact on yield than individual nutrient levels. Therefore, a further study measuring a greater number of factors was initiated. Method: In a joint study between staff in the Darwin and Katherine regions, six sites in both regions have been selected for evaluation. At the Katherine sites tree performance, climatic and management parameters are being measured. The performance of trees is being assessed by determining their growth patterns (recording at what time of the year the trees are producing new leaves, flowers or fruit), the yield and fruit quality. Data