Effect of silvicultural treatments on growth,fertility and capsule traits in seedling seed orchards of <Emphasis Type="Italic">Eucalyptus camaldulensis</Emphasis> and <Emphasis Type="Italic">E. tereticornis</Emphasis> |
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| Authors: | M Varghese N Ravi R Kamalakannan C E Harwood |
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| Institution: | (1) Institute of Forest Genetics and Tree Breeding, Post Box 1061, Coimbatore, 641002, India;(2) CSIRO Forestry and Forest Products, Ensis, Private Bag 12, Hobart, 7001, Australia |
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| Abstract: | The effects of nutritional treatments and the flowering promoter Paclobutrazol™ on tree growth and fertility were studied
in unpedigreed seedling seed orchards (SSOs) of Eucalyptus camaldulensis and E. tereticornis at two locations in southern India. At Pudukkottai, a semi-arid site in Tamil Nadu State, five treatments were applied: (1)
untreated control, (2) nitrogen (two doses of urea at 217 g N/tree), (3) nitrogen plus phosphorus (two doses of 312 g single
superphosphate), potassium (two doses of 83 g muriate of potash) and trace elements (two doses of 10 g sodium borate and 25 g
zinc sulphate), (4) pollarding trees at 4 m height with application of N, P, K and trace elements, (5) drenching with the
flowering promoter Paclobutrazol (0.25 ml active ingredient per cm of stem girth) along with N, P, K and trace elements. At
Panampalli, a higher-rainfall site in Kerala State, only treatments 1, 2 and 3 were applied. Four replicates of treatment
plots sized 18 m × 18 m, with 22–32 trees per plot were set up in each orchard in randomized complete block designs. Untreated
plots of E. camaldulensis and E. tereticornis at Pudukkottai displayed 12 and 21% fertile trees, respectively, in the first year of monitoring, while at Panampally the
percentage of fertile trees in untreated E. camaldulensis plots was higher at 72%, and that of E. tereticornis similar at 23%. Both species attained greater stem diameter at breast height at age 9 years at the higher-rainfall location
but there was no significant impact of fertilizer application on 9-year diameter at either site. Diameter was reduced by pollarding
and Paclobutrazol application at Pudukkottai. Only Paclobutrazol produced a significant increase in fertility in both species
for four successive years, increasing the percentage of fertile trees to 59 and 71%, respectively, for E. camaldulensis and E. tereticornis 1 year after application. The number of capsules produced per tree also increased significantly with Paclobutrazol application,
although the difference was comparatively less by the fourth year. The number of capsules per umbel did not differ significantly
between locations, whereas the germination rate varied between treatments although no consistent trends were observed. |
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| Keywords: | Eucalyptus Fertilizer Paclobutrazol Fertility Seed orchards Seed production |
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