Genetic Variation in Frost Tolerance, Uromycladium acaciae Rust Resistance, and Growth in an Acacia mearnsii Population

Genetic variation in frost tolerance, resistance to the rust fungus Uromycladium acaciae, growth, stem form, and gummosis were evaluated in 110 open-pollinated families of black wattle (Acacia mearnsii De Wild). Families were tested at six frost-prone sites in northern KwaZulu-Natal and southeastern Mpumalanga, South Africa. Frost-hardy provenances were susceptible to rust disease and had poor growth. Locally grown F1 seed sources that originated from cold-hardy Australian seed sources had better growth and were tolerant to rust, but at a cost of lower frost tolerance. Considerable genetic variation was observed between families within seed sources for frost damage (hfm2 = 0.77), rust incidence (hfm2 = 0.89), and height (hfm2 = 0.80). The corresponding narrow-sense heritabilities (hi2) were 0.30, 0.80, and 0.32. Genotype-by-environment interaction levels were low for most traits. Except for a strong genetic correlation between tree height and diameter (0.90), all the pairs of traits had weak to moderate genetic correlations. Recurrent selection will be successful in improving frost tolerance and rust incidence. However, the current population comprises limited germplasm that is both tolerant to frost and resistant to rust. Thus, we recommend infusing germplasm from known cold-hardy Australian provenances into the current population to increase genetic variation for frost tolerance, rust, and growth. Study Implications Black wattle (Acacia mearnsii De Wild) is widely planted in South Africa for bark extract and woodchip exports. The species is prone to frost damage and susceptible to rust fungus Uromycladium acaciae, two major limitations to its cultivation. In this study, 110 open-pollinated families of black wattle originated from its native range in Australia and local South African seed sources were studied for frost and disease tolerance. The results from this study suggest that there is considerable variation within species for frost tolerance and fungal disease. We suggest a tandem selection strategy for black wattle farming in South Africa to increase resistance to frost damage and fungal diseases.

Community narratives and local impacts of invasion in the Eastern Cape: A critical invasion ethnography of black wattle

Since 1995, the South African government has spearheaded a national invasive species campaign known as the Working for Water Program with the dual objectives of invasive species eradication and rural development. This national narrative on invasive species reflects a politicized research agenda and a wealth of material resources directed toward eradication, yet does not accurately portray the reality of invasion at the village level. In particular, Acacia mearnsii de Wild, or the black wattle tree, is classified as one of the worst invasive species in South Africa and a primary target for Working for Water, yet represents an important livelihood resource for rural communities and impacts community members differentially. To better understand these local rural realties, I use a critical invasion science approach to interrogate the local experiences and narratives of black wattle invasion in a rural pastoral community in the Eastern Cape. Within this community, local understandings and impacts of black wattle are nuanced, spatially variable, and reflect complex knowledge politics and political economies. As invasion research moves to incorporate the human and local dimension of invasion for improved policy, it is imperative to fully consider this differentiation of perspectives and impacts within the local community.

Acacia auriculiformis (northern black wattle).

Few other species can match the ability of A. auriculiformis to grow on harsh sites in the tropics. Its rapid early growth rate, ability to fix nitrogen, tolerance of infertile, acid, alkaline, saline or seasonally waterlogged soils and moderate dry seasons make it a useful species for the rehabilitation of degraded lands. It has been widely planted for fuelwood production, erosion control, ornament or shade mainly in Asia, but also in Africa and South America. The stem form can be improved significantly by selection and breeding, providing outstanding prospects for industrial plantations to produce paper pulp and other timber products.

Acacia mearnsii (black wattle).

A fast-growing, nitrogen-fixing tree adapted to a wide range of sites from the temperate and subtropical lowlands to tropical highlands. It yields bark extractives high in quality tannin, paper pulp, cellulose for rayon, charcoal, and fuelwood. The use of A. mearnsii tannin for production of waterproof wood adhesives for the reconstituted-wood industries is expanding. A useful species for erosion control, soil improvement, shade and shelter, and ornament.

COMPATIBILITY BETWEEN THE SPURR FUNCTION VOLUME AND THE KOZAK’S TAPER FUNCTION AND QUINTIC POLYNOMIAL VOLUMES FOR BLACK WATTLE TREES

When modeling the taper and volume, it is desired that the volume estimates obtained by using these two methods are compatible, where the total stem volume estimates shall not differ when using a total volume equation and the volume calculated by integrating the taper equation. There are several of such systems proposed in the literature, in which modifications in the volume and taper models were made to obtain compatible systems. This paper introduces an idea to obtain compatibility in a simpler way, without the need to modify the volume and taper models. Thus, the overall objective of this study was to develop and present a procedure to obtain compatibility between the Spurr function volume and the Kozak’s taper function and quintic polynomial volumes for Acacia mearnsii De Wild trees and compare the results to the traditional method of the same system of equations. The procedures proposed were applied on data on the Acacia mearnsii De Wild (black wattle) species in the towns of Cristal, Piratini, and Encruzilhada in the south of the state of Rio Grande do Sul, Brazil. The data set included 343 trees ranging from 5 to 10.75 years of age. The quality of the fitting for the volume and taper equations fitted using procedures 1 and 2 is similar, and both are compatible. The system of equations presented in procedure 2 is simpler to be applied when compared to procedure 1.

Adsorption behavior of gardenia yellow pigment on embedded spherical cellulose adsorbent

A spherical cellulose adsorbent embedded with black wattle extract (SABW) was prepared and used to adsorb gardenia yellow pigment (GYP). The result revealed that SABW presented excellent adsorption performance to GYP.

Methods of overcoming dormancy in seeds and initial development of Black Wattle

The objective of this work was to analyze the efficacy of different methods of dormancy break in seeds of Acacia mearnsii De Wild. The work was performed at the UFSM Botany Lab and Forest Nursery, in Frederico Westphalen, RS. The treatments were: (T1) control; (T2) immersion in hot water (90 °C) for 5 minutes, followed by rest; (T3) immersion in hot water (90 °C) for 10 minutes, followed by rest; (T4) chemical scarification with concentrated sulfuric acid for 3 minutes, followed by washing under running water; (T5) chiseling with concentrated sulfuric acid for 5 minutes, followed by washing under running water. The seeds were sown in plastic trays with Oxisol and vermiculite. The results were submitted to analysis of variance and data were differentiated by Test t with 5% of probability. The most efficient treatment to overcome dormancy was T2, presenting 81.29% of germinated seeds and IVG of 18.23 days for germination. This treatment was also the best for the variables of physical vigor and best performing root length and aerial part, and did not differ from improved treatments for diameter and green mass weight.