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  • Author or Editor: Russell J. Lewis x
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Rape (Brassica napua var. oleifera) plants were grown in a continually circulating hydroponic system with perlite as the root support medium. Two experiments (I and II) were supplied with complete nutrient solutions (modified Hoaglands) differing only in added boron ((I) 0.40 (normal), 0.20, or 0.04 mg L-1, and (II) 0.40, 0.02, or <0.01 mg L-1). A minimum of nine replications was examined in each experiment. Photosynthesis (Pn) and stomatal conductance (SC) readings were taken on leaves 8, 12, 16, 20, and 24 when the leaves attained 70% to 90% full expansion ((I) days 58, 76, 86, 97, 106 and (II) days 50, 70, 78, 88, and 97 respectively following planting dates). Measurements were taken at solar noon (± two hours) using a portable Pn analyzer (Analytical Development Company). Rape plants in experiment I appeared morphologically similar, did not exhibit B deficiency symptoms, and did not have significant Pn or SC. Morphological development of plants in experiment II varied widely among treatments. Photosynthesis and/or SC mean values were significantly reduced at leaf stages 16 to 24 as B availability decreased. Treatment contrasts within and between experiments suggest that the 0.02 to 0.04 mg L-1 range of added B is critical for the development of normal Pn and SC in leaves. These findings support our previous research report that the natural ontogeny of oilseed rape is greatly affected within a narrow range of B availability.

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Heating `Golden Delicious' apples (Malus domestica Borkh.) for 4 days at 38C or pressure-infiltrating them with a 4% CaCl2 solution reduced decay and maintained fruit firmness during 6 months of storage at 0C. Heating reduced decay caused by Penicillium expansum Link ex Thorn by ≈30%, while pressure infiltration with CaCl2 reduced decay by >60%. Pressure infiltration with CaCl2 after heating reduced decay by ≈40%. Pressure infiltration maintained firmness best (>84 N), as measured with a manually driven electronic fruit-firmness probe, followed by heat and CaCl2 (76 N), heat alone (71 N), and no treatment (control) (60 N). Force vs. deformation (FD) curves from a puncture test with a fruit-firmness probe mounted in a universal testing machine showed that fruit heated before storage were firmer than all nonheated fruit, except those pressure-infiltrated with 4% CaCl2. However, FD curves also showed that apples pressure-infiltrated with 4% CaCl2 differed quantitatively from apples in all other treatments, including those heated.

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