Effect of chromium toxicity on germination and early seedling growth in melon (Cucumis melo L.)

This study was conducted to determine and compare the inhibitory effects of chromium on seed germination and early seedling growth of melon (Cucumis melo L.). Chromium applications were controls; 2.5, 5, 10, 25, 50, 75, 100, 200 and 300 mgl-1 Cr in germination stage, and controls; 2.5, 5, 10, 20, 30, 40, 50, 60 and 70 mgl-1 Cr in early seedling stage. Excess chromium was limited to germination rate, germination index, mean germination time and germination uniformity index values in germination level. Radicle length, radicle fresh and dry weight, hypocotyll length, hypocotyll fresh and dry weight, growth tolerance index and seedling relative growth rate was negatively affected by the increased chromium concentrations at the seedling stage. Response of seedlings to chromium was more than that of seed germination. This event is based on the impermeability of seed coats and selectivity of embryos against chromium

Germination and early seedling growth of Pinus densata Mast. provenances

We studied seed germination and early seedling growth of Pinus densata to explore the range of variability within the species and to inform afforestation practices. Phenotypes were evaluated at a forest tree nursery under conditions that support Pinus yunnanensis, one of the presumed parental species of P. densata. Seeds were collected from 20 open-pollinated trees within each of eight autochthonous populations representing the natural distribution of P. densata in China to assess variation in germination traits and early seedling growth, and to examine the relationships among these traits. Results showed that seeds from all populations germinated and seedlings established successfully. There were significant differences among populations in 13 of 14 traits evaluated. Seed germination and early seedling growth were strongly related to seed size and seed weight. Bigger seeds germinated earlier and faster than small seeds, and seedling size was positively correlated with seed size. Some germination traits were strongly and significantly correlated with climatic variables associated with the provenance of the studied populations. Based on these observations, we conclude there were large, significant, and biologically important differences among P. densata populations in seed germination and seedling growth traits. The observed variability probably reflects a high degree of adaptive differentiation among populations that is likely to be relevant for future afforestation