Paternal and maternal effects on the response of seed germination to high temperatures in Eucalyptus globulus

Abstract

& Context High temperature stress in nurseries germinating Eucalyptus globulus seed is an important problem affecting germination synchrony and rate. Where there is a risk of hightemperature stress, then the choice of female parent may be important. This issue is particularly relevant to the production of full-sib families from mass-supplementary pollination where there may be opportunities for seed producers to manipulate the directionality of the crossing done in seed orchards.& Aims This study aimed to quantify the maternal versus paternal influence of seed sensitivity to high temperature stress during germination. & Methods A diallel crossing scheme involving four genotypes was used to test the relative importance of male and female genetic influences on the germination and development of E. globulus seed and their response to high temperature stress. Seed was germinated at optimum (25°C) and supra-optimal (32°C and 37°C) temperatures, and six traits

Genetic control of Eucalyptus globulus seed germination

“…The data were summarised into four response traits for each experimental unit of 50 seeds, two measuring proportions and two measuring rates as detailed in Rix et al (2012a;2012b). The proportional data included germination proportion (the proportion of seeds sown that germinated-Germ/Sown) and the proportion of germinated seeds that developed into normal seedlings (Normals/Germ).…”

“…In the present study, the crossing design does not allow the cause of the maternal genotype influence on seed germination traits to be determined. However, in a study of reciprocal crosses of E. globulus, Rix et al (2012b) showed that both the male and female genotype may affect various aspects of seed germination and early seedling development, independent of seed size, but the response to high temperature stress was more influenced by the maternal than paternal parent.…”

“…Seed extraction as well as germination procedures and assessment are detailed in (Rix et al 2012a;2012b). In brief, the number of seeds per capsule and weight of 100 seeds were recorded for the sample from each ramet.…”

“…A subsequent study using reciprocal matings of E. globulus undertaken in the same seed orchard with replication of the female genotype showed that there are paternal and maternal effects on the germination response (Rix et al 2012b). This result argues for at least some influence of the nuclear genotype, but the response to high temperature stress was shown to be more influenced by the maternal parent (Rix et al 2012b).…”

“…A subsequent study using reciprocal matings of E. globulus undertaken in the same seed orchard with replication of the female genotype showed that there are paternal and maternal effects on the germination response (Rix et al 2012b). This result argues for at least some influence of the nuclear genotype, but the response to high temperature stress was shown to be more influenced by the maternal parent (Rix et al 2012b). The four genotypes studied were from one (Western Otways) of thirteen native races of E. globulus, which are genetically differentiated in many functional traits (Dutkowski and Potts 1999;Stackpole et al 2011), including drought susceptibility (Dutkowski and Potts 2012).…”