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  • Author or Editor: Sherif Sherif x
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‘Honeycrisp’ (Malus ×domestica) apples were harvested from a total of 17 mid-Atlantic orchards during 2018 and 2019 to verify a previously published bitter pit prediction model. As in the previous study, bitter pit incidence was associated with low calcium (Ca) levels and high ratios of nitrogen (N), potassium (K), and/or magnesium (Mg) to Ca in the fruit peel and excessive terminal shoot growth. The best two-variable model for predicting bitter pit developed with the 2018–19 data set contained boron (B) and the ratio of Mg to Ca (R 2 = 0.83), which is different from previous models developed with data from three individual years (2015–17). When used to predict the bitter pit incidence of the 2018–19 data, our previous best model containing the average shoot length (SL) and the ratio of N to Ca underestimated the incidence of bitter pit. The model is probably biased because one or more important variables related to bitter pit have not yet been identified. However, the model is accurate enough to identify orchards with a low incidence of bitter pit.

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Nutrient technique (NFT) and deep water culture (DWC) hydroponic systems were used to grow sweetpotao to study the effect of four nutrient solution treatments on: translocation of nutrients and plant and microbial population growth in split-root channels. 'TU-155'cuttings (15 cm) were prerooted for 30 days in sand in 4 cm CPVC pipes 46 cm in length. A modified half Hoagland (MHH) solution was supplied ad libidum. After 30 days, plants were removed and the roots of each plant were cleaned and split evenly between two channels (15 cm deep by 15 cm wide by 1.2 m long). four plants per channel. Nutrient solution treatments (replicated) were: MHH-MHH: MHH-Air, MHH-deionized water (DIW); and monovalent (Mono) - divalent (Dival) anions and cations. Solution samples were continuously collected at 7-day intervals for microbial population profiling. Plants were harvested after growing for 120 days in a greenhouse. Storage roots, when produced, were similar in nutritive components. However, no storage roots were produced in Air or Mono channels and only a few in DIW. Fresh and dry weights for storage roots and foliage were highest in MHH-MHH in both NFT and DWC in repeated experiments. Population counts indicated that nutrient solution composition influenced the size of the microbial population in NFT. Population counts were highest in Dival channels. The microbial population counts (4.20-7.49 cfu/mL) were. relatively high in both NFT and DWC systems.

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