Responses of Papaya Plants in a Potting Medium in Containers to Flooding and Solid Oxygen Fertilization

摘要

Papaya (Carka papaya L.) production in Florida is concentrated in areas with a high water table that are prone to flooding resulting from storms or hurricanes. This can limit production because the crop is sensitive to flooding stress. Studies were conducted to examine physiological responses of papaya to flooding a portion of or the entire root system and if flooding stress can be reduced by fertilization with solid oxygen compounds. Six-month-old 'Red Lady' papaya plants in Promix~R potting mediumwere divided into 3 flooding treatments: 1) 100% of roots submerged; 2) ~75% of roots submerged; or 3) non-flooded. In separate experiments, plants in each flooding treatment were subdivided into oxygen fertilization treatments by adding different amounts of either magnesium peroxide (MgO,) or calcium peroxide (CaO,) or no oxygen fertilization to the potting medium prior to flooding. Redox potential (an indication of oxygen content) of the soil solution, net CO, assimilation, stomatal conductance, leafchlorophyll index, chlorophyll fluorescence, and plant tissue dry weights were assessed. Short-term flooding (2-3 days) of ~75% or 100% of the root system resulted in plant stress as determined by the physiological variables measured. However, plants eventually recovered from flooding after they were unflooded. Application of Mg02 or CaO, to flooded plants did not affect any of the physiological variables measured or dry weights for most chemical fertilization treatments. However, 5 g of MgO, increasedleaf area and total plant dry weight of flooded plants compared to no oxygen fertilization or fertilization with 10 g of MgO,. This is in contrast to results of a previous study with 3-week-old papaya seedlings in a gravelly loam soil whereby soil application of CaO, reduced the impact of flooding on plant dry weight. Thus, more research is needed with different age plants, different concentrations of solid oxygen fertilizers in different soil types to more thoroughly assess the effects of amending soilwith solid oxygen fertilizer on reducing the impact of flooding stress.