176 P. D. DOGRA 



The good growth rate and the good cone and seed production (Troup, 

 1921) in planted blue pine stands shows that the species adapts well to 

 the Kumaon region. 



SILVICULTURAL CHARACTERISTICS 



Blue pine is a light demander. It grows and flowers best in open 

 situations exposed to bright sunshine; it tolerates different degrees of 

 shade but not deep shade. 



It grows well both in moist and dry climate but winter snow is 

 necessary for good growth. In dry climate, low-level blue pine is 

 susceptible to attacks of Avceuthobium minutissimum. 



Trees are not long-lived but begin to flower and set seed at an early 

 age. Mature trees seed well every year and abundantly after short 

 intervals. The seedlings are drought -resistant and well adapted to grow 

 on a variety of soils. 



The species is highly drought and cold resistant, frost and snow 

 hardy, and can tolerate a combination of extreme cold and aridity. 



Blue pine is an efficient colonizer of open grass lands, landslips, 

 moraines, and flood plain deposits. It grows best on well -drained moist 

 and deep soil, mostly alluvia, flood deposits, and decomposed mica-schists 

 with gravel rocks and boulders. 



Good seed-set and high fertility from an early age, coupled with 

 efficient seed dispersal and high adaptability to a variety of soils, 

 climates, and altitudes seem to be highly advantageous to the species in 

 acquiring a wide distribution ranging from favorable to adverse climates. 



REPRODUCTIVE BARRIER BETWEEN THE PROVENANCES 



Pollination in the blue pine forests takes place during the warm and 

 dry sunny weather of the spring. The male cones during this period enlarge, 

 become yellow in color, and shed their pollen. Pollen is received by the 

 fully receptive and turgid micropylar flaps of the ovules situated at the 

 base of the scales. The micropyles are exposed to the wind in spring by 

 the opening of the scales due to sudden elongation of the central axis 

 of the female cone. The different periods of pollination in the blue pine 

 populations are geared to the spring and climatic conditions of their 

 provenances . 



In Himachal Pradesh and Uttar Pradesh pollination in the moist lower- 

 level blue pine (4,000 feet) occurs about 7 to 10 days earlier than in 

 the moist upper-level blue pine (10,000 feet). Female receptivity in the 

 moist lower-level blue pine is of very short duration (4 days) after which 

 most of the micropyles shrivel up (Dogra, 1964b) and direct cross-pollination 

 with the moist upper-level blue pine becomes difficult. Intermediate 

 condition in regard to pollination and female receptivity periods exists 

 in different trees growing in the middle altitudes and the gene exchange 

 between lower- and upper-level populations in the moist monsoon zone 

 takes place mostly through these intermediate tree forms. The same 

 condition exists in the low- and high-level blue pine populations of dry 

 and arid zones . 



