POLLEN TUBE GROWTH IN NONPAREIL ALMOND IN RELATION TO POLLEN GENOTYPE, TEMPERATURE AND COMPETITION AMONG MIXED POLLEN

Pollen tube growth in Nonpareil almond was studied under three different temperature regimes: 1) day temperature 22°C, night temperature 12°C; 2) day temperature 15°C, night temperature 12°C; and 3) field conditions.
Pollen tube growth was monitored by light microscopy after hand cross pollination with two cross-compatible cultivars.
Pollen germination on the stigma surface was found to be related to temperature, and germination began 6 hours after pollination.
Pollen tube penetration for Peerless pollen in the upper part of the style began after 12 hours at 22°C, and after 24 hours at the other temperatures.
There was no significant difference between the number of pollen tubes observed for all temperatures at days 2, 3, 4 and 6. Pollen tubes reached the base of the style after three to four days and were observed in the micropyle after 4 days in all treatments except for Keane at 15°C, in which it did not enter the micropyle until day 6. The percentage of pollen tubes in the ovule under field conditions was always higher than in the controlled growth room experiments.
Competition between Keane and Peerless pollen when applied together on Nonpareil stigmas was investigated by observations of pollen genes in the resultant embryos.
Comparison of 5 different isozyme loci showed that the frequency of Peerless pollen genes in the embryo was twice that of Keane genes.
Self-pollination of Nonpareil resulted in the pollen tube being rejected on the stigma as well as in the style.
Deposition of callose on the tip without swelling was found to be a common indication of incompatible pollen.

II International Symposium on Pistachios and Almonds

A. Vezvaei

Aniline blue, Cross-pollination, male gametes, pollen

https://doi.org/10.17660/ActaHortic.1998.470.35