EFFECTS OF TEMPERATURE ON POLLEN VIABILITY IN MANGO CV KENSINGTON

The response of pollen development to low or high temperature regimes was studied to determine the conditions suitable for the formation of fertile pollen in the mango cv. 'Kensington'. The phase most sensitive to the degree and duration of temperature stress was that from meiosis to the pre-vacuolate microspore (about 3 d duration at 25/20 °C) though vacuolated microspores were also sensitive to low temperature. Night temperatures below 10 °C resulted in pollen grains with a low viability (< 50%). A temperature between 15 and 33 °C during the phase from meiosis to the pre-vacuolate microspore was optimum for pollen development (70-85% pollen viability). Analysis of field records showed a linear negative correlation between percentage of pollen viability and number of days which had a mean night temperature lower than 10 °C during the period from meiosis to early mature stage (y = 77·7-3·4x, r2 = 0·60). The temperature sensitive phase was estimated to begin 155 degree days D = Σ[(Tmax + Tmin)/2 - 10] before anthesis and to end 78 degree days before anthesis. This equation may be useful as a means of predicting pollen viability in the field from temperature records and thus fruit set, date of maturity and yield. It may also aid in the selection of areas for growing mangoes in marginal climates.