|Authors: ||N. Sukhvibul, S.E. Hetherington, A.W. Whiley, M.K. Smith, V. Vithanage|
|Keywords: ||floral morphology, pollen viability, sex expression, mango|
Trees of two mono-embryonic (‘Irwin’ and ‘Sensation’) and two poly-embryonic (‘Nam Dok Mai’ and ‘Kensington’) mango cultivars were exposed to winter temperatures to induce flowering.
They were subsequently transferred into controlled environment glasshouse rooms under day/night temperature regimes of 15/5, 20/10, 25/15 and 30/20°C for 20 weeks.
Inflorescence development only occurred on trees that were maintained at 20/10, 25/15 and 30/20°C. Higher temperatures generally increased the inflorescence size while there was an inverse effect on the mean number of flowers per inflorescence with 619.6 at 20/10°C decreasing to 431.3 at 30/20°C. There was an inverse relationship between the length of the anthesis period and temperature.
Low temperatures at 20/10°C decreased the percent hermaphrodite flowers in poly-embryonic cultivars but increased the percentages in mono-embryonic cultivars.
Style length and stigma width was reduced when the trees were held at 20/10°C compared to those trees held at either 25/15 or 30/20°C. Trees of ‘Kensington’ grown at 20/10°C mainly produced flowers which had short styles (0.62 mm) and small stigmatic surfaces while ‘Nam Dok Mai’ and ‘Irwin’ trees produced some flowers which had deformed ovaries or fused ovaries.
A decrease in percent hermaphrodite flowers and floral changes which occur in poly-embryonic cultivars when inflorescences develop under low temperatures (20/10°C), are likely factors contributing to their low fruit set when grown in subtropical climates.
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