Girth Increment Research Articles

Seasonality and Phenology in a Dry Tropical Forest in Ghana

(1) Flowering, fruiting, leaf production, leaf fall and girth changes all show a strong seasonal pattern in a tropical forest and grassland/thicket mosaic in Ghana. Moisture deficits limit phenological activity although patterns vary among species. (2) Flowering and fruiting occur throughout the year. Dry-fruited species fruit principally in dry seasons. Fleshy-fruited species fruit in either wet or dry seasons, although fleshy fruits are most abundant in wet seasons. Species grouped according to habitat and life-form show similar patterns of flowering and fruiting. (3) Leaf flushing is entirely limited to wet seasons, although not all species or individuals produce new leaves each wet season. Leaf fall occurs in dry seasons; 19% of forest species and 55% of grassland/thicket species became fully leafless during the study period. (4) Girth changes are closely related to rainfall and foliage phenology. The amplitude of girth changes is related to the habitat of the species, with greater seasonal changes occurring under more exposed conditions. Net girth increments over the 15-month period were negative, due to the unusually low rainfall.

Some observations on the effect of grassing‐down, nitrogen fertilisation and irrigation on the growth, leaf nutrient content and fruit quality of young golden delicious apple trees

AbstractIn a 3 year trial the growth and leaf nutrient content of newly planted Golden Delicious/MM 106 apple trees was compared under grassed‐down and clean cultivated conditions. With no fertiliser applications grassing down, compared with cultivation, decreased shoot extension and trunk girth increment in all three seasons and total dry weight of both tops and roots of trees at the end of the 3 year period. Grassing‐down generally decreased total N and increased concentrations of P, K and Ca in the leaves. Generally, in the third season, the mineral composition of the fruit paralleled that in the leaves. Application of fertiliser N to cultivated plots in the second and third seasons had no significant effect on tree growth; N fertilisation significantly increased tree growth and total leaf area per tree under grassed‐down conditions, particularly in the third season. During the third season irrigation had only a small effect on the growth of trees from the grassed‐down non‐fertilised plots. However, there was a large positive interaction between N fertilisation and irrigation on tree growth, total dry weight of both shoots and roots of trees and on fruit size.

Early Exploitation of Hevea Rubber Trees by Puncture and Short-Cut Tappings

SUMMARYPuncture tapping and one-eighth spiral (S/8) tapping, both combined with Ethrel stimulation, were compared with conventional half spiral (S/2) tapping of immature Hevea trees. Stimulated puncture-tapped trees in some experiments yielded more rubber and had much more sucrose in the latex than unstimulated half-spiral tapped trees. Yields of puncture-tapped trees also increased with increase in the quantity of Ethrel and the number of punctures, but were not affected by the size of puncture. Girth increments of the trees and percentage dry rubber content of the latex were approximately equivalent in all three methods of tapping.

Effects of Shade on the Growth and Cropping of Apple Trees. I. Experimental Détails and Effects on Vegetative Growth

SummaryCox’s Orange Pippin apple trees on M.26 rootstock were shaded so as to receive 37, 25 or 11 % of full daylight during the post-blossom growing season in either or both 1970 and 1971 and their growth compared with that of control trees. Shading had direct and also residual effects, the latter in the year following treatment. It reduced the number and weight of new shoots, the fresh weight per unit length of shoot, girth increment and leaf thickness and weight per unit area, but increased the concentrations of K and Mg in the leaves. Residual effects included a reduction in the number of shoots but increases in girth increment, in weight per unit length of shoot and in leaf dry weight per unit area and per unit fresh weight. These latter results are thought to be a consequence of reduced competition for assimilates as a result of a drastic residual effect on the number of fruits carried. In the year after shading the concentrations of N, P, Mg and Ca in the leaves were reduced and that of K increased.

Estimates of genetic parameters of certain characters in Hevea brasiliensis

Heritability estimates of five quantitative characters, namely, yield, girth, girth increment, virgin bark and renewed bark thickness, of the breeding Phase III Hevea families have been obtained by variance component analyses. In general, the combined heritability estimates for various characters were low to moderate. The heritabilities of these characters based on female variance components, however, were high, suggesting that considerable improvement of each of the characters could be achieved in properly designed experiments.Estimates of heritability for average yields (Range: 0.11-0.34) over different years showed that the first three years' yield was adequate for predicting estimates of genetic variance for the average of five years' yield.Correlation studies on yield with other characters indicated considerable influence of environment, with genetic correlations accounting for about 0.07 to 0.36 in the characters studied.Expected direct response to selection in yield and correlated response in yield to selection for girth at opening and virgin bark thickness have been calculated using three arbitrary values of selection intensity. The efficiency of the correlated response was found to be approximately half that of the direct response. However, the indirect selection for yield using virgin bark thickness appeared to be more favourable than that using the girth at opening favoured by earlier workers.

Influence of Jarrah Leaf Miner on the Growth of Jarrah

SUMMARY Outbreaks of the leaf miner Perthida glyphopa in the jarrah forest of Western Australia have been occurring over an ever-increasing area since the early 1950s. Approximately 0.4 M ha of forest and 1.0 M ha of partly cleared farm land were infested in 1971. In addition, jarrah in scattered groves on the coastal plain has been infested by the leaf miner for at least 60 years. Some 23 per cent of trees are resistant to the leaf miner's attack.The effect of infestation on girth increment was determined by comparing the growth of resistant and susceptible trees. Over the four years of measurement (1968–71), the annual losses for girth increment in the susceptible trees were 71, 83, 75 and 64 per cent in the forest, and 47, 41, 46 and 33 per cent at a site on the coastal plain. The magnitude of losses was influenced by the density of the insects.

The effect of summer pruning and nitrogen on growth, cropping and storage quality of Cox’s Orange Pippin apple

SummaryPruning in late summer was compared with winter pruning on mature 23-year-old spur pruned trees of Cox’s Orange Pippin on M.2 rootstock. Two nitrogen treatments were superimposed, namely a standard dressing of 126 units N (sulphate of ammonia) applied in March as compared with 288 units N (nitrate of soda) applied in mid-August at the time of summer pruning. Summer pruning reduced trunk girth increment, advanced blossom development, increased the amount of red colour on the fruits and drastically reduced the incidence of bitter pit in stored fruit. The treatments did not affect cropping. Nitrogen treatments had no overall effect upon the incidence of bitter pit, but in the first season, when bitter pit was most prevalent, high levels of N applied in August reduced the amount, a similar trend being recorded the following year.

Apple rootstock studies: growth of trees on three clonal rootstocks planted with or without roots

SUMMARYTrees of Cox's Orange Pippin on M.IXa, M.26 and MM. 106 were planted either normally with roots or without roots to simplify the planting operation. Pruning treatments were superimposed, the trees being cut back at planting, left unpruned the first year and cut back the second year, or left entirely unpruned. All trees survived. After two growing seasons the trees were lifted and weighed. Removal of all roots before planting reduced shoot growth, trunk girth increment, final tree weight and incremental weight. However, on all rootstocks, trees planted without roots and left unpruned were similar in size when lifted to those planted with roots and cut back at planting in the orthodox manner.In a complementary trial lasting one season Cox's Orange Pippin trees on M.26 were planted with or without roots. All trees were cut back at planting, and four times of planting were compared. The mid-April planting included trees that had been stored at 2.8 °C and trees that had been bedded-in outdoors. There we...

An Experiment in Pruning Cox’s Orange Pippin Apple Trees in Alternate Years

SummaryFive pruning treatments were compared on Cox’s Orange Pippin on M.II rootstock, viz.1. Open-centre tree, established-spur pruned2. Open-centre tree, renewal-pruned3. Delayed open-centre tree, established-spur pruned4. Delayed open-centre tree, renewal-pruned5. Regulated-pruned tree.At 15 years, secondary pruning treatments were begun and carried on for a further 7-year period, the trees being pruned by the same methods but either annually or in alternate years. Differences in growth and cropping between trees pruned to open-centre and delayed open-centre shapes were small, but open-centre trees cropped more heavily than did delayed open-centre trees when renewal-pruned, probably on account of their greater branch spread. The method used in pruning the laterals had an effect upon cropping during the first 10 years. At the end of the trial there was no effect of either primary or secondary treatments upon trunk girth, neither was there a significant difference in girth increment between the secondary...

Inducing Precocious Cropping On Young Dr. Jules Guyot Pear Trees with Gibberellic Acid

A single spray of gibberellic acid (GA) at blossom time doubled the final set and yield of 4-year-old Dr. Jules Guyot trees without reducing the fruit size. GA affected the fruit shape, but this was detrimental only at a high concentration (100 p.p.m.) ; it also hastened fruit ripening by about a week and increased the percentage of seedless fruits. Although a heavy spray at 50 p.p.m. had the most effect, a light spray at the same concentration was more effective in conserving the plants’ resources by avoiding the early development of an excessive number of fruitlets prior to the June drop.The total shoot growth, the number of shoots and buds, and the girth increment were reduced by GA at 50 p.p.m. applied as a heavy spray but the mean length of shoots and internodes remained unaffected.

STUDIES IN SYSTEMATIC BARK MORPHOLOGY

SummaryThe production of xylem and phloem sets up tangential stretching forces through the bark. In the living inner bark the resulting strains are mainly accommodated in Dipterocarpaceae by the formation of expansion tissue. The strain set up by a given annual girth increment decreases with increasing girth to a low steady amount at about 90 cm (3 ft) girth. Phloem formation in a mature tree only sets up small strains. These increase from zero at the cambium to a maximum at the surface. Many barks have more expansion tissue than this accounts for; the rest accommodates the strains set up by xylem formation. The tangential extent of the expansion tissue at a given distance from the cambium in any bark is in fact a measure of the ratio of the xylem and phloem growth rates. The three groups of Bark Types in Dipterocarpaceae with different amounts of expansion tissue (Whitmore, 1962a) are therefore groups with different xylem/ phloem ratios.Phloem growth rate determines periderm pattern and sometimes sloughing rate too. Fissure shape is controlled by periderm pattern and sloughing rate. The xylem growth rate is similar in different groups of dipterocarps. Thus the xylem/phloem ratio is an inverse measure of the phloem growth rate which cannot be measured directly. There is therefore a correlation between the xylem/phloem ratio and periderm pattern, sloughing and fissure shape.Similarities within the three groups of Bark Types in Dipterocarpaceae arise, therefore, from the dependence of periderm pattern, sloughing and fissure shape on the xylem/phloem ratio. Differences within the three groups arise from features, which are independent of the ratio: inter alia the phloem proliferation tissue, which probably varies phenotypically, and the sloughing mechanism.It follows that the xylem/phloem ratio is an important factor in the interpretation of diptero‐carp bark construction.There is no evidence of growth periodicity in the barks examined. Calculations show that the phloem is often conducting for more than 1 year to an observed maximum of 11.4 years; this is in marked contrast with most reports for temperate phloems.

THINNING EXPERIMENTS IN JARRAH COPPICE (EUCALYPTUS-MARGINATA)

SUMMARY The degree of thinning, in the form of a reduction in the number of stems per stump; has been studied, together with-its effect on the-growth, development and form of the residual shoots. In good, quality forest thinning has so far failed to produce any effect on either the height or diameter growth of the remaining shoot or shoots. In other areas while there has been no effect on height growth there has been an increased girth increment in the thinned shoots. On 110 occasion has an adverse effect of early coppice thinning on either growth or form been recorded.