Identification Of Male Sterile Genotypes In Interecotypic Hybrid Switchgrass (Panicum virgatum L.) By Pollen Viability and Self-Fertility Tests.

Male sterility (MS) systems, which are extensively used in field-scale hybrid seed production by generating male-sterile female lines, have not been investigated in switchgrass breeding to date. This research is based on the hypothesis that the F2 plants that are developed via selfing of F1 hybrids obtained from wide crosses, segregate for male sterility in switchgrass. Two complementary inbreds including a male sterile line are required to produce heterotic hybrids in switchgrass that are expected to develop in future with some self-compatible genotypes. The objective of the research was aimed to develop male sterile plants in switchgrass. Interecotypic crosses between lowland and upland plants were carried out, with a total of nine crossing combinations, to develop first generation (F1) hybrid progenies. The genetic origin of thus produced F1 plants was examined and confirmed using simple sequence repeat (SSR) markers. Genetically true F1 plants were selected for next cycle self pollination in order to obtain F2 progenies. Male fertility of selected F1 plants was examined via pollen stainability and germination test. The Lugol solution method was used for pollen stainability test. For pollen germination testing, a standard growing media containing 1 % agar, 0.8 M sucrose, 1.28 mM boric acid and 1.27 mM calcium nitrate was used. Bagging and pollen germination showed no sterile genotype in F1 generation while the pollen stainability test failed to ratify switchgrass pollen fertility. The F2 plants are currently being grown inside greenhouse, and the male sterile genotypes will be examined and confirmed by pollen germination and selfing assessments.