Influence of temperature, germination duration and cultivar on in vitro pollen germination and pollen tube growth in coconut

Abstract

Temperature, germination duration and cultivars are important factors influencing pollen germination and pollen tube length of plants and thereby effecting fruit set and yield. To quantify the influence of nine temperatures from 10°C to 50°C at 5°C intervals, four germination durations of 1,3,5 and 7 hours and five coconut cultivars viz., WCT, CGD, MGD, MOD, MYD on in vitro pollen germination and pollen tube length, an investigation was carried out during 2014 and 2015 at C.P.C.R.I. Regional Station, Kayamkulam, India. Maximum pollen germination (71%) and pollen tube length (243µm) was observed at 30°C and least at 50°C. Pollen germination required 5 hours at 10 - 20°C, 3 hours at 25-35°C and 1 hour at 40-50°C for reaching maximum value. Pollen tube growth required 7 hours at 10°C, 5 hours at 20 and 30°C, 3 hours at 15,25,35 and 40°C and 1 hour at 45 and 50°C to reach maximum value. WCT cultivar was found to have significantly more pollen germination percentage than the other cultivars. The cultivars which would perform better in predicted future climate change scenario are presented. Mean cardinal temperatures estimated for pollen germination and pollen tube length were Topt. 28.5°C and 29.5°C , Tmin. 4.3°C and 8.5°C , Tmax. 52.8°C and 51.2 °C respectively.