Development of specific and nonspecific reponses to stress in Pinus sylvestris L. at population level in a gradient of drought years

The results of monitoring the types of seed reproduction systems and 12-year experiment on self-pollination in Scots pine have been used to analyze the adaptive reaction norm of three seed-productivity traits: self-fertility coefficient, seed plumpness, and number of seeds per cone. The development of nonspecific and specific responses to stress has been followed in a gradient of years with early droughts (1991, 1995, 2001, 2007, 2012). The results show that the reduction of seed yield and the proportion of inbred progeny and progeny of drought-tolerant forms in annual seed production increase proportionally to the strength of climatic stress experienced by the population.