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- Author or Editor: Jennifer A. Stewart x
Abstract
A greenhouse experiment was conducted using ornamental privet plants (Ligustrum japonicum Thunb.) to determine the effects of irrigation treatment (daily vs. every 2 days), container type (plastic vs. clay), and mix (redwood-sand; pine-sand; pine-soil; or sphagnum peat-perlite-sand) on the fate of applied N. The sinks for N that could be accounted for consisted of uptake by plants, N absorbed and/or adsorbed by the mix and container, and N leached. Growth rate and uptake of applied N was greatest for plants in plastic containers which were irrigated daily. The type of mix used did not appear to significantly affect plant growth. Compared with all other treatments, larger proportions of the applied N were absorbed and/or adsorbed by redwood-sand or pine-sand mixes in plastic containers irrigated on alternate days. Larger proportions of applied N were lost in leachate water from plastic containers that were irrigated daily than all of the other treatment variables. Unaccounted-for N (denitrified) was greater for plastic containers (16.2%) than clay containers (10.8%), and pine mixes had significantly greater proportions of applied N denitrified (17.7% for pine-sand and 18.9% for pine-soil) than redwood (9.3%) or peat (8.1%).
‘Honeycrisp’ is a relatively new apple cultivar highly susceptible to physiological disorders, such as soggy breakdown. The overall objective of this study was to identify preharvest weather parameters that influence the incidence of soggy breakdown over the different phases of fruit development. Using weather data and evaluation of fruit quality from three sites in Ontario, two sites in Quebec, and one site in Nova Scotia from 2009 to 2011, and data from four sites in Ontario from 2002 to 2006, a model for soggy breakdown incidence (SBI) was developed to predict the level of susceptibility in ‘Honeycrisp’ apples. This model uses primarily two weather variables during the last phase of fruit development [91 days from full bloom (DFB) to harvest] to accumulate an SBI index during the growing season, from full bloom to harvest. Cool (temperature <5 °C) and wet conditions (precipitation >0.5 mm) during this last phase resulted in increased soggy breakdown susceptibility levels. The predictions of the SBI model resulted in 68% of well-estimated cases (threshold of ±5%) (RMSE = 6.45, EF = 0.28, E = −0.04). Furthermore, firmness was linked to soggy breakdown, in addition to weather conditions, revealing a positive effect of high firmness at harvest on the development of the disorder. However, the effect of fruit quality attributes (e.g., internal ethylene concentration, starch index, firmness, and soluble solid content) by themselves, without considering weather conditions, revealed no relationship with the incidence of soggy breakdown.