Varietal variation and yield trials of Leucaena leucocephala (koa haole) in Hawaii

"November 1977."Cover title.Bibliography: p. 29.Mode of access: Internet

Hawaiian Plumerias

Reprint June 1972The plumeria is an important ornamental tree in Hawaii as well as in Florida, the West Indies, Central America, India, China, Indonesia, Australia, islands of the Pacific basin, and some other tropical regions. This booklet covers all aspects of plumeria cultivation in Hawaii

Propriedades e utilização como lenha de árvores fixadores de N2

World deforestation and reforestation values are cited, and the increasing need for fuelwood tree plantings is noted. Tropical reforestation involves about 1 million hectares annually, of which less than 20% is believed to survive. Estimated tropical fuelwood needs alone, however, require 3 million hectares annually. Fuelwood remains the most cost-effective source of energy for rural poor, and charcoal demands are increasing worldwide. World deforestation is occurring primarily in the tropics (10-20 million ha/year), largely in relation to fuelwood demands (1,200 million m3/yr). The loss of newly planted forests to fire is stressed as a serious problem, notably for pine and eucalypt forests. It is suggested that over half the 650 known species of nitrogen-fixing trees (NFT) are suitable for fuelwood and charcoal, and many have wide present use. The fuelwood properties of 32 major NFT species are given, together with information on their uses and environmental constraints. Leucaena data are used to illustrate that tree age and density have little effect on calorific values, but have major influence on moisture content and specific gravity of the wood. It is stressed that calorific values should be quoted for the bone-dry wood, and then readjusted downward to reflect moisture in the wood as burned. The need is stressed for yield data from NFT biomass plantings at high densities, with appropriate controls of locally-important trees (including non-fixing trees, notably eucalyptus). Disadvantages are cited for monocultural plantings of single fuelwood species, and advantages suggested for mixed plantings of NFT species together with high-yielding trees that lack the ability to fix nitrogen.O trabalho salienta a extensão de devastação de florestas e do reflorestamento, bem como o aumento considerável da necessidade de plantações de árvores, para produção de lenha. O reflorestamento em áreas tropicais representa cerca de 1 milhão de hectares, anualmente, dos quais apenas 20% realmente sobrevivem. Entretanto, estimativas feitas sobre as necessidades de lenha mostram que são necessários 3 milhões de hectares, anualmente, somente para atender a essa finalidade. A lenha permanece como a fonte de energia mais importante no meio rural, e a demanda de carvão está crescendo em todo o mundo. As maiores devastações de florestas estão ocorrendo nos trópicos, onde 10-20 milhões de hectares por ano são cortados para atender principalmente a demanda por lenha (1.200 milhões m3/ano-1). A perda de novas florestas por queimada acidental é apontada como um problema sério, notadamente nos reflorestamentos de pinheiro e eucalipto. Mais da metade das 650 espécies conhecidas de árvores fixadoras de N2 são adequadas para a produção de lenha e carvão e muitas delas já são usadas no momento. As propriedades em termos de lenha de 32 das mais promissoras árvores fixadoras de N2 são apresentadas junto a informações sobre o uso e principais problemas de cultivo. Resultados obtidos com Leucaena são usados para ilustrar que a idade da árvore e a densidade têm pouco efeito sobre os valores caloríficos, mas têm grande influência sobre o teor de umidade e peso específico da madeira. É enfatizado que o valor calorífico deveria ser citado para a madeira completamente seca e, então, reajustado de modo a refletir o teor de umidade da madeira, quando queimada em condições normais. É apontada a necessidade de dados de produtividade de biomassa de leguminosa, em plantios de alta densidade, com apropriados controles de árvores não-fixadoras de N2, localmente importantes (provavelmente o eucalipto). As desvantagens das monoculturas de espécies produtoras de lenha e as vantagens de plantios mistos de árvores fixadoras de N2, junto a árvores de alta produtividade, mas incapazes de fixar N2, são discutidas

Selection of Psyllid-Resistant Forage Varieties from an Inter-Specific Breeding Program of \u3cem\u3eLeucaena leucocephala\u3c/em\u3e with \u3cem\u3eL. pallida\u3c/em\u3e

Leucaena (Leucaena leucocephala) pastures for beef cattle production are productive and sustainable; however, susceptibility to the psyllid insect (Heteropsylla cubana) has limited expansion of current commercial cultivars into more humid areas (\u3e 800 mm/yr) (Shelton and Dalzell 2007). Psyllids can also cause intermittent damage in lower rainfall regions during humid periods. The psyllid, which arrived in Australia in 1986, is a leaf-sucking insect specific to the Leucaena genus, feeding on the growing tips of susceptible cultivars (Bray 1994). Psyllid damage can reduce production by as much as 50-70% in humid regions and 20-50% in subhumid environments (Bray 1994; Mullen and Shelton 2003). Work on psyllid resistance in the Leucaena genus through the 1990s showed that several Leucaena species, including the tetraploid L. pallida, had good levels of resistance (Mullen et al. 2003). A breeding program to develop psyllid-resistant varieties began in 2002 at The University of Queensland (UQ) based on the F1 inter-specific hybrids between L. leucocephala and L. pallida (known as ‘KX2’), developed at the University of Hawaii (Brewbaker 2008). Between 2002 and 2005, UQ initiated a program of recurrent selection in an attempt to produce stable outcrossed KX2-derived lines but inbreeding depression for yield and poor forage quality led to a change in the breeding strategy, and a backcrossing program was implemented between 2005 and 2008. Two cycles of backcrossing to elite L. leucocephala ssp. glabrata material were completed followed by 2 cycles of progeny testing and selection for self-compatibility to achieve stability and uniformity (2009 - 2012). Forty elite psyllid-resistant lines were then evaluated to identify the most suitable lines for release to industry. This paper describes the results of these trials