Nitrous oxide treatment increases the proportion of viable pollen and pollen size in Limonium perezii

Interspecific crosses between L. sinuatum and L. perezii have produced hybrids (Limonium siNZii™) utilized by the ornamental industry. The inclusion of genotypes as parents in the breeding program depends, among other factors, on their fecundity. Two L. perezii genotypes, per11 and per275 with comparatively low male fertility (zygote success <40±16% for both genotypes when used as pollen donors in intraspecific crosses), were selected for this study. We had observed that pollen viability and the number of zygotes obtained from the two genotypes improved after nitrous oxide (N₂O) treatment. The aim of this study was to evaluate and to understand the effect of N₂O on pollen viability, pollen size, and number of zygotes produced per number of crosses done (zygote success) when used as pollen parents following treatment of immature inflorescences. The proportion of stained pollen increased up to 1.7 times in per11 and up to three times in per275; the size of pollen grains also increased between 1.2 and 1.5 times in both genotypes; and the zygote success was 20% higher when per11 was used as a pollen parent. These findings support the hypothesis that the improvement in zygote success following N₂O treatment is associated with an improvement in pollen viability, and an increase in pollen size. It is proposed that, when pollen viability is an issue, changes in proportions of pollen stained and size can be used to identify the optimum stage of inflorescence development to apply N₂O treatment for best pollen viability and higher zygote success.