The effects of temperature on in vitro pollen germination and pollen tube growth of Pistacia spp.

Abstract

The pollen germination and pollen tube growth among nine Pistacia genotypes was quantified in order to identify differences in the tolerance of pollen to temperature variations. The effect of temperature on in vitro pollen germination and pollen tube growth was investigated in Pistacia vera (Uygur, Atli, Kaska, Sengel, Kavak), P. atlantica, P. khinjuk, P. terebinthus and P. palaestina. When pollen was incubated in a germination medium for 24 h in darkness, distinct differences were observed in pollen germination and pollen tube growth at different temperatures. Pollen was collected at anther dehiscence and was exposed to temperatures from 5 to 40 °C at 5 °C intervals. There were some differences between the percentage of pollen germination and pollen tube growth at different temperatures. Pistacia species and cultivars were found to range from most tolerant to most susceptible, depending on pollen characters. Pollen germination of the genotypes ranged from 83% to 97% and pollen tube length ranged from 697 to 1270 μm. A modified bilinear model best described the response to temperature of pollen germination and pollen tube length. Genotype variation was found for cardinal temperatures ( T min, T opt and T max) of pollen germination percentage and pollen tube growth. Mean cardinal temperatures averaged over nine genotypes were 6.7, 23.9 and 41.1 °C for maximum percentage pollen germination and 6.4, 23.9 and 39.8 °C for maximum pollen tube length.