Comparative adaptation of seed germination and seedling growth to environmental factors in two Picea plant species

Picea crassifolia is a species that has been successfully and widely introduced by raising seedlings in the desert areas of North China. This study was conducted to compare the adaptations between P. crassifolia and P. mongolica in seed germination to temperature,light conditions,water,and salt stress and seedling growth to water and salt stress and sand burial. Moreover,seed viability was also tested by TTC and compared in two plant species after being stored for two years in their habitats. The results showed that:(1) The seed viability of P. mongolica and P. crassifolia decreased from 79% and72% to 19% and 5%,respectively,during the course of seed storage for two years in their habitats.(2) The temperatures for germination in P. mongolica and P. crassifolia were 15- 30℃ and 10- 30℃, respectively, and the optimal temperatures were 25℃(72%) and 25/15℃(69%), respectively. Instead of 10℃ and 10/30℃, there were no significant differences between the germination rate of the two species in other temperatures.(3) The optimal light conditions for germination were 14 h light/8 h dark(67%) in P. mongolica,whereas they were 24 h light or 24 h dark in P. crassifolia.(4) There were no significant differences in IGR(Initial Germination Rate),RGR(Recovery GerminationRate),ISL(Initial Seedling Length),and RSL(Recovery Seedling Length) between P. mongolica and P. crassifolia at a water potential from-2.7 MPa to 0 MPa.(5) When the concentration of NaCl was 220 mmol/L and 250 mmol/L,the IGR of P. crassifolia was higher than that of P. mongolica, whereas the RGR was not significantly different at NaCl concentrations from 0 to 450 mmol/L. The ISL of P. crassifolia was significantly higher than that of P. mongolica at the NaCl concentration of 50 mmol/L and 100 mmol/L.(6) Seedling emergence in P. crassifolia was significantly higher than that of P. mongolica at sand burial depths from 0 to 2.0 cm. The optimal sand burial depth was 0.5 cm in P. mongolica and 0.5-1.5 cm in P. crassifolia. Therefore,P. crassifolia has stronger adaptations than P. mongolica in seed germination and seedling growth. If the effective measures(sowing time,sowing depth,and moisture management,etc.) in the course of raising seedlings are taken,then P. mongolica will be introduced widespread and raised from seedlings in the desert areas of North China.