نوع مقاله : مقاله پژوهشی
نویسندگان
1 نویسنده مسئول، مربی پژوهشیار مرکز تحقیقات کشاورزی و منابع طبیعی استان خراسان رضوی، مشهد ص پ 488- 91735
2 مربی پژوهشی مرکز تحقیقات کشاورزی و منابع طبیعی استان گلستان، گرگان
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
This research project investigates factors causing decline of major tree species including prosopis cineraria and Acacia nilotica in southBaluchestan in the period 1997-2000. These factors include pests and diseases occurrences, precipitation and soil characteristics. Sampling procedures for insects include direct collection on host tree, light trap use and laboratory rearing. Furthermore, along with collecting of sample rain, major components include sulfate, nitrate and chloride and main cations such as calcium and magnesium were analyzed. Soil sampling of 0-50 depth was conducted to determine mineral elements as well. Finally the above mentioned factors were quantified and analyzed using the statistical method of multi-variable regression. The results obtained revealed a positive correlation between the components. Water stress was the single most significant factor affecting trees growth and survival. It should be noted that the rate of precipitation within the last ten years has decreased from 253.6 mm in the year 1989 to 32.9 in the year 1993. Insect pests especially wood-borers are another important growth-reducing factor. The results obtained in the basis of the incubation of the samples being suspected of disease showed no pathogenic agent involved.
کلیدواژه‌ها [English]
)