Pollen storage studies in sugar apple (Annona squamosa L.) cv. Balanagar

Abstract

Annona cv. ‘Arka Sahan’ essentially needs assisted pollination with sugar apple pollen for commercial fruit production. However, there is no perfect synchronization in flowering of the pollen source sugar apple cv. Balanagar with that of cv. ‘Arka Sahan’. So, an attempt was made to store the pollen of the former to assure its availability as and when cv. ‘Arka Sahan’ flowers need to be pollinated. In vitro pollen germination was assessed using different concentrations of sucrose (5%, 10% and 15%) with and without boric acid (100 ppm). Pollen collected on the second day of anthesis showed maximum germination (43.47%) in 5% sucrose + 100 ppm boric acid while those collected on first day of anthesis did not show any germination. Pollen collected at different times of the day showed a rapid decrease in pollen germination from maximum germination at 6 am (36.55%) to no germination at 2 pm. The maximum pollen germination was in 10% sucrose + 100 ppm boric acid combination for the stored pollen as well as pollen collected during late hours of the day. Pollen stored under varying temperatures lost viability within 1 month at 4°C while pollen stored at −196°C in liquid nitrogen retained germination for 2 months. Pollen germination and pollen tube growth were progressively reduced with storage time. Structure of stored pollen examined using Scanning Electron Microscope (SEM), revealed deformed and shriveled pollen structure. The results of this study indicated that the Annona pollen tends to be viable for a period of 2 months.