Canopy Pruning Research Articles

THE BRAZILIAN LYCHEE INDUSTRY – PRESENT AND FUTURE

In 2007, about 1,500 ha of land in Sao Paulo were given over to the lychee industry compared to 350 ha ten years ago. Sao Paulo state accounts for roughly 70% of the total planted area, followed by the neighboring states of Minas Gerais (15%), Parana (5%) and minor industries in Goias, the Federal District, Espirito Santo and Rio de Janeiro. Approximately 25% of the area is in full production, 35% is beginning production and 40% contains young non-bearing trees. The main 'Bengal' cultivar accounts for 99% of the planted area in old and new orchards. It has a pronounced biannual bearing habit which is clearly illustrated by the drastic fluctuation in supply of fresh fruit (2,500 MT in an 'on year' compared to 400 MT in an 'off year'), as well as by the difference in price paid by consumers which varies from US$ 3.50 to 10.00/kg. The forecast is for a doubling of current production in the next five years and for over 10,000 MT by 2020. Because lychee production in Brazil relies upon one cultivar (Bengal) and on one major region - Sao Paulo, the harvesting peak is highly concentrated in December (65 to 70%), therefore prices are lower during this period. The Brazilian lychee industry produces fresh fruit mainly for its domestic market; only tiny amounts are exported to Europe. There is no importation from other producer countries. The main constraints on lychee production in Brazil include the lack of information regarding adequate technologies for canopy management, pruning, nutrition, irrigation, pest management and post harvest handling of the fruit, as well as variable genetic material (early- and late-season cultivars in relation to 'Bengal') with fruits that have a high percentage of good quality pulp. However, since 2004, a group of 20 growers from different regions, under the co-ordination of the University of Brasilia, have introduced new cultivars ('Kwai May Pink', 'Kwai May Red', 'Feizixiao', 'Tai So', 'Souey Tung', 'Salathiel', 'Emperor', 'Haak Yip' and 'Kaimana') from Australia, which are now being assessed in 20 different farms across five different states (Sao Paulo, Minas Gerais, Goias, the Federal District and Bahia). It is expected that in a few years' time 'Bengal' will be gradually replaced by these new cultivars and the harvesting period will be extended from September to March. In addition, many orchards of 'Bengal' are located in warm areas (approximately 25% of the total planted area in Brazil); this makes them unproductive because fruiting is extremely erratic if there is no chilling to induce flowering. These orchards would set and bear fruits more constantly and earlier in the season if they were top-worked with new cultivars that have low chilling requirements. In Brazil, there is a huge potential for the lychee to become as popular as the kiwi fruit was in the 90s providing that the industry manages to supply good quality fruits for a longer period and at an affordable price.

Vascular-Streak Dieback: A New Encounter Disease of Cacao in Papua New Guinea and Southeast Asia Caused by the Obligate Basidiomycete Oncobasidium theobromae

ABSTRACT The basidiomycete Oncobasidium theobromae was identified as the cause of a devastating disease of cacao named vascular-streak dieback (VSD) in Papua New Guinea in the 1960s. VSD now causes losses among cacao seedlings and kills branches in mature cacao trees throughout Southeast Asia and parts of Melanesia. The characteristic symptoms include a green-spotted chlorosis and fall of leaves beginning on the second or third flush behind the stem apex, raised lenticels, and darkening of vascular traces at the leaf scars and infected xylem. Eventually complete defoliation occurs and, if the fungus spreads to the trunk, the tree will die. O. theobromae is a highly specialized, near-obligate parasite of cocoa. It is a windborne, leaf-penetrating, vascular pathogen, and may have evolved as an endophyte on an as yet unidentified indigenous host. The rate of disease spread on cocoa is limited because basidiocarps develop only on fresh leaf scars during wet weather, and basidiospores remain viable for a few hours on the night they are shed. Consequently, very few new infections occur beyond 80-m from diseased trees. Transmission of the disease through seed or infected cuttings has not been demonstrated. Strict quarantine measures applied to the movement of intact plants are crucial in reducing spread of the disease. Integrated management, including the planting of less susceptible genotypes, nursery construction and management, canopy pruning and shade management, provides effective control.

Irradiation on teak and pine agroforestry system and the effect on growth of soybean

Teak and pines are the largest tree forests in Central of Java so that they are very potential to be developed as an argoforestry system. The average Relative Irradiation Fraction (RIF)’s in the teak and pines trees are 50% and 14% respectively. Meanwhile, soybean is sunloving crop potentially to be cultivated in the agroforestry system. The aim of the research was to study the response of the soybean (Glyicine soya) varieties to the tree canopy pruning. The experiment was conducted at teak and pines forest area (vertisol and ultisol soil type respectively) arranged in split plot design. The main plot factor was pruning (no pruning and pruning) and the sub plot factor was variety (Wilis, Pangrango and Brawijaya). The teak and pines canopy pruning (50% lower part of canopy) increases the incident irradiation among the trees by 70%-89% or equal to 600-1000 μ mol m-2 s-1 and 80% or 840 μ mol m-2 s-1 respectively. The increase in the irradiation among the trees enhances the photosynthetic rate of soybean. The response of the soybean to the enhancing irradiation is higher in specific leaf area (SLA). Biomass production and seed yield of the soybean increases due to the canopy pruning. The seed yield of soybean increase respectively from 0.12 to 0.57 tons ha-1 and from 0.78 to 1.74 tons ha-1 in no pruning and pruning teak and pines agroforest. The Pangrango variety produces the highest yields of seed, thus it is potential to be cultivated as intercrops in a teak and pines agroforestry system.© 2006 Jurusan Biologi FMIPA UNS SurakartaKey words: soybean, teak, pines, agroforestry

Irradiation on teak and pine agroforestry system and the effect on growth of soybean

Teak and pines are the largest tree forests in Central of Java so that they are very potential to be developed as an argoforestry system. The average Relative Irradiation Fraction (RIF)’s in the teak and pines trees are 50% and 14% respectively. Meanwhile, soybean is sunloving crop potentially to be cultivated in the agroforestry system. The aim of the research was to study the response of the soybean (Glyicine soya) varieties to the tree canopy pruning. The experiment was conducted at teak and pines forest area (vertisol and ultisol soil type respectively) arranged in split plot design. The main plot factor was pruning (no pruning and pruning) and the sub plot factor was variety (Wilis, Pangrango and Brawijaya). The teak and pines canopy pruning (50% lower part of canopy) increases the incident irradiation among the trees by 70%-89% or equal to 600-1000 μ mol m-2 s-1 and 80% or 840 μ mol m-2 s-1 respectively. The increase in the irradiation among the trees enhances the photosynthetic rate of soybean. The response of the soybean to the enhancing irradiation is higher in specific leaf area (SLA). Biomass production and seed yield of the soybean increases due to the canopy pruning. The seed yield of soybean increase respectively from 0.12 to 0.57 tons ha-1 and from 0.78 to 1.74 tons ha-1 in no pruning and pruning teak and pines agroforest. The Pangrango variety produces the highest yields of seed, thus it is potential to be cultivated as intercrops in a teak and pines agroforestry system.© 2006 Jurusan Biologi FMIPA UNS SurakartaKey words: soybean, teak, pines, agroforestry.

Biomassa da rebrota de copas de pau-rosa (Aniba rosaeodora Ducke) em plantios sob sombra parcial em floresta primária

Este estudo propõe uma nova metodologia de exploração do pau-rosa (Aniba rosaeodora Ducke) em substituição ao método tradicional, predatório, de corte raso. Avaliando-se a biomassa da rebrota de copas (galhos e folhas) e de cepas cortadas a 1 m de altura do solo, será possível inferir sobre o manejo de plantios visando maximizar a produção de óleo essencial desta espécie. Os plantios estão localizados na Reserva Florestal Adolph Ducke, Manaus, Brasil. Treze anos após a poda das copas e do corte das árvores a 1 m do solo, o peso seco da rebrota da copa (39,5 kg) foi significativamente superior ao peso seco de galhos e folhas das árvores testemunha (23 kg) e da rebrota das cepas (13,7 kg), revelando que a poda da copa estimulou maior produtividade de galhos e folhas das árvores do plantio. Como o peso do fuste representou 85,5% da média do peso total das árvores e a produtividade de óleo é diretamente proporcional á biomassa aérea, a exploração atual é predominantemente feita através do corte raso das árvores. A alta capacidade de rebrota da copa e o maior rendimento de óleo a partir de galhos e folhas em relação à madeira, no entanto, indicam que o manejo dos plantios desta espécie poderá ser feito através da poda da copa das árvores, evitando a destruição total das árvores e uma possível extinção da espécie.

Canopy and environmental control of root dynamics in a long‐term study of Concord grape

Below-ground carbon allocation represents a substantial fraction of net photosynthesis in plants, yet timing of below-ground allocation and endogenous and exogenous factors controlling it are poorly understood. Minirhizotron techniques were used to examine root populations of Vitis labruscana Bailey cv. Concord under two levels of dormant-season canopy removal and irrigation. Root production, pigmentation, death and disappearance to a depth of 110 cm were determined over two wet and two dry years (1997-2000). There was continual root production and senescence, with peak root production rates occurring by midseason. Later in the season, when reproductive demands for carbon were highest and physical conditions limiting, few roots were produced, especially in dry years in nonirrigated vines. Root production under minimal canopy pruning was generally greater and occurred several weeks earlier than root production under heavy pruning, corresponding to earlier canopy development. Initial root production occurred in shallow soils, likely due to temperatures at shallow depths being warmer early in the season. Our study showed intricate relationships between internal carbon demands and environmental conditions regulating root allocation.

GROUND BRYOPHYTE COMPOSITION AND SYNUSIA STRUCTURE UNDER SIX TYPES OF YOUNG CONIFEROUS FOREST PLANTATIONS IN THE UPPER MINJIANG RIVER

Bryophytes on the ground under six types of artificial forests, Picea balfouriana forest (P), Pinus tabulaeformis forest (Y), Pinus armandii forest (H), Larix kaempferi forest (L), Picea balfouriana-Pinus tabulaeformis forest (P-Y) and Pinus tabulaeformis-Pinus armandii forest (Y-H), were investigated in the upper Minjiang River in order to understand the bryophyte composition and synusia structure of these different forest types. In the 19 bryophyte species identified, only 13, 10, 7, 11, 9 and 10 species were present in the P, L, H, Y-H, Y and P-H forests, respectively. Four mosses, Brachythecium glaciale, Thuidium cymbifolium, Entodon concinnus and Eurhynchium savatieri, were common in all six plantations. Another three mosses, Entodon macropodus, Mnium spinosum and Polytrichum formosum, occurred only in the Picea balfouriana forest. The highest frequency of bryophyte occurrence was under the P forest (90%) and the lowest frequency under the H forest ( 17.65% ). Thuidium cymbifolium had the highest frequency (60%) of all species under the P forest, and the second was Brachythecium glaciale (50%). The predominant species, based on the importance value, was Thuidium cymbifolium under the P forest and Brachythecium glaciale, occurred under the other five plantations, which indicated that Brachythecium glaciale was the most common moss species in the study area. In all forests, the P forest had the highest bryophyte diversity (Shannon-Wiener index, species richness index) and the H forest had the lowest diversity. The lowest Simpson index was calculated for the H forest and the highest one for the P forest. The highest similarity index (Sorensen similarity) occurred between the H and Y forests (0.89) and the lowest similarity index between the P and H forests (0.40). The greatest percent coverage (17.79%±1.67%), shoot density ((3 807.11±412.90) shoots·m -2 ) and thickness ((19.89±1.69) mm) of bryophytes occurred under the P forest, and the lowest values (0.41% ±1.49%, (27.99±367.95) shoots·m -2 , and (1.80±1.51) mm, respectively) under the H forest. For the Y, L, Y-H and P-H forests, ground bryophyte cover was 5.20%±1.58%, 2.44%±1.58%. 2.73%±1.61%, and 2.71%±1.61%, respectively, shoot density was (623.08±391.71), (566.13±391.71), (253.38±398.41), and (188.69±398.41) shoots·m -2 , respectively, and average bryophyte thickness was (9.60±1.61), (14.93±1.61), (9.59±1.63), and (6.69±1.63) mm, respectively. No statistical differences (p0.05) were found in any of these measures among the Y, L, Y-H and P-H forests. The low bryophyte diversity and limited structure development (density, coverage, thickness) found under all six plantations indicate that, in general, these are poorly developed bryophyte communities. Our results show that the best bryophyte community have developed under the spruce forest with a relatively open canopy and low tree density. Our results suggest that tree thinning or canopy pruning would be an effective measure for improving bryophyte development under dense forests.

Multiple risk factors in root survivorship: a 4-year study in Concord grape.

• Minirhizotron techniques were used to examine root lifespan in Vitis labruscana (Concord grape) for roots born in four different years that varied in rainfall. • Experimental vines were given irrigation (irrigated or not) and canopy pruning treatments (minimal or balanced). Root survival was assessed from 1997 through 2000 and analysed using Cox proportional hazards regression. Model covariates included pruning, irrigation, vine yield, soil depth, root diameter, time of root birth, and numbers of neighboring roots. • Soil depth, root diameter and time of birth consistently influenced root lifespan in all years (P<0.05). Deeper and coarser roots had longer lifespans. Roots born near bloom were shorter-lived than roots born later in the season. Pruning and irrigation influenced root lifespan in some years but their effects seemed to vary with growing-season environmental conditions. • These data underscore the value of long-term studies in distinguishing factors that consistently affect root lifespan from those that change annually with environmental conditions, and emphasize the diversity in life histories of fine roots within a species.

Assessing root death and root system dynamics in a study of grape canopy pruning

Defining root death in studies of root dynamics is problematic because cell death occurs gradually and the resulting effects on root function are not well understood. In this study, metabolic activity of grape roots of different ages was assessed by excised root respiration and tetrazolium chloride reduction. We investigated changes in metabolic activity and patterns of cell death occurring with root age and changes in root pigmentation. Tetrazolium chloride reduction of roots of different ages was strongly correlated to respiration (R2 = 0.786). As roots aged, respiration and tetrazolium chloride reduction declined similarly, with minimum metabolic activity reached at six weeks. Tetrazolium chloride reduction indicated that the onset of root browning corresponded to a 77% reduction in metabolic activity (P &lt; 0.001). Anatomical examination of roots at each pigmentation stage showed that even though some cells in brown roots were still alive, these roots were functionally dead. The effect of using different definitions of root death in relation to root survivorship was determined in a study of ‘Concord’ grapes with two pruning treatments, using three criteria for root death: browning, blackening or shriveling, and disappearance. There was no effect of vine pruning on root life span when life span was defined as the time from first appearance to the onset of browning. However, if death was judged as the point when roots either became black or shriveled or disappeared, vine pruning decreased root life span by 34% and 40%, respectively (P &lt; 0.001), and also increased the decay constant for root decomposition by about 45% (P &lt; 0.001). We conclude that the discrepancy among determinations of root life span assessed with different definitions of death might be partly caused by the latter evaluations of root life span incorporating a portion of root decomposition in definitions of root death.

Impacts of live canopy pruning on the chemical constituents of Douglas-fir vascular tissues: implications for black bear tree selection

The impact of live canopy pruning on the carbohydrate and terpene content of vascular tissue was investigated in the lower bole of Douglas-fir ( Pseudotsuga menziesii). Cambial zone vascular tissue samples were collected from pruned and unpruned trees in the lower bole and within the live canopy. Current year's radial growth was estimated from the mass of vascular tissue removed from the 800 cm 2 sample area. Chemical analyses were conducted to determine the concentration of carbohydrates and terpenes in the samples. Results indicated that two years following treatment, pruning resulted in reduced growth and decreased carbohydrate content of the vascular tissue. Pruning had no effect on the terpene concentration of the vascular tissue. The impact of pruning on the foraging selection of black bears ( Ursus americanus) was evaluated by surveying bear damaged trees in a 50 acre stand of pruned and unpruned timber. Odds ratios indicate that black bears were four times more likely to forage unpruned Douglas-fir than pruned Douglas-fir. Tree selection may be explained in part to the higher availability of carbohydrates in the unpruned tree with respect to the pruned tree.

Antitranspirant and Root and Canopy Pruning Effects on Mechanically Transplanted Eight-year-old ‘Murcott’ Citrus Trees

Abstract Two groups of 8-year-old ‘Murcott’ [Citrus reticulata Blanco × C. sinensis (L.) Osbeck hybrid?] trees on rough lemon (C. jambhiri Lush.) rootstock were transplanted with a Vermeer tree digger in March and July, respectively. Root and shoot pruning and a 2% (v/v) spray of a pinolene-based antitranspirant (Vapor Gard) formed the treatments either individually or in combination. Canopy size at transplanting had the greatest effect on tree water-stress and subsequent tree growth and yield. The antitranspirant and root pruning tended to reduce leaf water-stress, but the effects generally were small and nonsignificant. Root pruning also seemed to stimulate new root growth. After transplanting, roots grew 2 to 3 m beyond the soil ball in one year. Four years after transplanting there were virtually no differences in tree height or canopy volume. Cumulative yield was less for trees with 30% and 85% of their foliage removed as compared to those with 50% removed. Trees pruned 50% bore fruit the year after transplanting and consistently yielded more throughout the study.