Abstract:

One year old outstanding seedlings and seedlings of superior families of L. Kaempferi(LAMB.)CARR.were planted in a hedged orchard in a spacing of 60cm×50cm.Ortets in the experimental area were hedged in three different types:Low-sized table type, ortets were topped at the height of 20cm above ground and all lateral branches remained on the stems were truncated at the length of 4cm-5cm from the base; Middle-and long-sized cylindricality types, ortets were topped at the height of 70cm and 140cm respectively from the ground and branches remained on the stem were treated by the same method mentioned above.Repeated topping was taken to keep the height of ortets under control.Cuttings were collected twice a year.For the first time, 3-4 shoots were cut off at the length of 1cm-1.5cm from the base and the others were cut off at the base in the end of April for preparing woody cuttings. Second collection was done in the late of June when new shoots grew more than 13cm long.3-4 shoots(preferred shoots less than 13cm)were remained on each truncated branch and allowed to continue growing.The other shoots were all cut off at the base for preparing semi-woody cuttings.Cutting production and its rooting ability were studied each year.Influence of truncated length of lateral branches on shoot sprout were also investigated. Growth response of ortets varied with hedging types.Compared with ortets of middle-sized cylindricality type and low-sized table type, thelong-sized cylindricality ortets were the biggest one in size; and produced as many as 284.6 cuttings in average each year when they were 3-year-old which is significantly higher than ortets of low-sized table type(135.5 cuttings)and middle-sized cylindricality type(209.8 cuttings).There were no significant differences in rooting ability among cuttings(both of woody and semi-woody cuttings)taken from ortets hedged in the different types.Rooting to ground of woody cuttings was ranged 70.0-77.8% if cuttings were treated with 0.005% IBA. However rooting ability could be expected even better for semi-woody cuttings(87.7%-90.0%).For ortets with long-sized cylindricality type, rooting percentage of cuttings collected from branches close toground(0-20cm from ground)was significantly higher than that of cuttings collected from the top of ortets(110-140 cm)which showed the positional effect. It was harmful for the occurrence of new shoots to cut off lateral branches at the base, but large quantity of twigs came out on the remained portion of branches as the branches were truncated at the length of 4-5 cm from the base.It was found that optimal period for collecting woody cuttings was the stage of development when the needles on the ortets fully extended in the late spring.

Key words: Larix kaempferi (LAMB.) CARR., Hedged types of ortets Cutting production, Rooting percentage,