The present study investigated the adaptability and growth of a fast-growing clone (BN1) of N. cadamba planted as short-rotation plantation species in the
Summary
Four inoculation methods were investigated for assessing the clonal variation of eucalypts in susceptibility to bacterial wilt (Ralstonia solanacearum). The results showed that these inoculation methods obviously differed in the disease infection process, clonal variation and clonal mean repeatability in susceptibility of stock materials inoculated. For each inoculation method, the clonal effect was consistently significant over the assessment period. Root-collar suspension injection method (RSI) yielded the highest relative clonal variation (0.67±0.086) and clonal mean repeatability (0.92±0.038) in both disease infected incidence and severity at the end of assessment, attributable to the enhanced genetic variation or low environment effect. For a given inoculation method, an early assessment time might exist for maximizing relative clonal variation or repeatability. It is desirable in breeding to adopt an inoculation method and/or efficient assessment time with high clonal variance component, which would in turn improve the efficiency of clonal screening.
Oleoresin is a major non-forest product collected from commercially mature or near mature pine trees. Efforts have been made to increase oleoresin yield, but basically limited to the genetic improvement of planting materials and the application of chemical stimulants to tapping surface of trees. Nutrition management may play a role, particularly for pine stands suffering from soil acidification and degradation. We set up a field experiment including application of water retainer, NPK complex fertilizer, lime and borax in different combinations to pine stands for oleoresin tapping with extremely low soil pH value and nutrition. Lime significantly affected the annual yield of oleoresin tapped from two pine species studied (P < 0.05). Among 3 levels of lime applied (0, 100, 200 g/tree), the oleoresin yield increased as the dose increased in slash pine, but was highest at 100 g/tree in masson pine. The doses of 167 g and 133 g of lime per tree were optimal or close to be optimal for slash pine and masson pine, respectively. The effects of other three matters applied were statistically insignificant (P > 0.10). In addition, all of the four matters applied did not influence the growth of both pine species. We concluded that proper use of lime alone may generate 15% to 35% of gain in oleoresin production for pine plantations with similar soil conditions in the region. We also discussed the potential of comprehensive soil or site management, and proposed further research for improvement of pine oleoresin production.
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