Effects of feeding high levels of cactus (Opuntia ficus-indica Mill) cladodes on urinary output and electrolyte excretion in goats

A study was conducted to determine the effects of feeding spineless cactus cladodes on diuresis and urinary electrolyte excretion in goats. Five bucks were used in a 5 x 5 Latin square experiment with 17-day periods. Experimental diets contained (g/kg dry matter (DM) basis) 370, 470, 570, 670, and 770 spineless cactus cladodes. Water consumption from feed and urine output increased linearly (P<0.05) as the level of cactus cladodes in the diet increased. However, water intake from drinking was low and unaffected by cactus cladode level. Creatinine clearance and urinary Na excretion were similar for all dietary treatments while K excretion decrease linearly (P<0.05) as the level of cactus cladodes in the diet increased. Feeding cactus cladodes caused diuresis and reduced urinary K excretion in goats. Possible reasons for these effects include water over-consumption from cactus cladodes and high dietary K intake. (C) 2007 Elsevier B.V. All rights reserved.

Potential of Cactoblastis cactorum as a vector for fungi pathogenic to pricklypear, Opuntia inermis

In Australia, fungi associated with larvae of the biological control agent Cactoblastis cactorum may contribute to the control of the exotic weed pricklypear (Opuntia inermis), C, cactorum larvae were assessed for their ability to vector pathogenic fungi into O, inermis by the infestation of larvae with fungal suspensions. Six fungal isolates caused disease after being carried into the host on external surfaces of larvae, and propagules of one isolate (UQ5109) initiated disease after being transferred from the cladode epidermis into the host by larvae feeding on the plant. Scanning electron microscopy revealed extensive hyphal growth on the external surfaces of larvae infested with several of the isolates. Fungi isolated from field-grown O, inermis cladodes were tested for pathogenicity to this plant in an in vivo plant assay. In total, 152 isolates were screened, 22 of which infected the host in pathogenicity tests. Only 1 (UQ5115) infected undamaged host tissue, whereas the remainder required the host to be wounded before infection could proceed. The majority of isolates were only weakly pathogenic, even when inoculated via wounds, suggesting that most were either saprophytes or weak parasites. This study demonstrates that it is possible for larvae of C, cactorum to transmit fungal pathogens into O, inermis tissue and it has provided a sound basis for future field work to determine the contribution that fungi make to the control of O. inermis, (C) 2001 Academic Press.

Soil water dynamics and evapotranspiration of forage cactus clones under rainfed conditions

Abstract: The objective of this work was to evaluate soil water dynamics in areas cultivated with forage cactus clones and to determine how environmental conditions and crop growth affect evapotranspiration. The study was conducted in the municipality of Serra Talhada, in the state of Pernambuco, Brazil. Crop growth was monitored through changes in the cladode area index (CAI) and through the soil cover fraction, calculated at the end of the cycle. Real evapotranspiration (ET) of the three evaluated clones was obtained as the residual term in the soil water balance method. No difference was observed between soil water balance components, even though the evaluated clones were of different genus and had different CAI increments. Accumulated ET was of 1,173 mm during the 499 days of the experiment, resulting in daily average of 2.35 mm. The CAI increases the water consumption of the Orelha de Elefante Mexicana clone. In dry conditions, the water consumption of the Miúda clone responds more slowly to variation in soil water availability. The lower evolution of the CAI of the IPA Sertânia clone, during the rainy season, leads to a higher contribution of the evaporation component in ET. The atmospheric demand controls the ET of clones only when there is higher soil water availability; in this condition, the water consumption of the Miúda clone decreases more rapidly with the increase of atmospheric demand.

Study of carbohydrates present in the cladodes of Opuntia ficus-indica (fodder palm), according to age and season

Types and content of carbohydrates were evaluated by chemical (spectrophotometric assay) and physicochemical (Thin Layer Chromatography - TLC and High Performance Liquid Chromatography - HPLC) methods in some Opuntia ficus-indica varieties according to age and season. The samples comprised four varieties of palm (giant, copena F1, clone 20, and round palm). The results demonstrated that the four varieties of palm contain a good quantity of neutral and acid sugars in both summer and winter seasons. However, samples collected in the summer presented a higher content of carbohydrates specially glucose, fructose, galactose, xylose, and arabinose. The tertiary cladode (old cladode) presented almost the double content of sugar found in the quaternary cladodes (young cladodes). Pectic polysaccharides were sequentially extracted with water at 60 ºC, and EDTA at 60 ºC solution resulting in Water-Soluble Pectin (WSP) and a Chelating-Soluble Pectin (CSP) respectively. Galacturonic acid was detected in the fractions WSP and CSP. However, the fraction CSP presented the highest content of sugar acid.

ABOVE-GROUND BIOMASS ESTIMATION OF OPUNTIA FICUS-INDICA (L.) MILL. FOR FORAGE CROP IN A MEDITERRANEAN ENVIRONMENT BY USING NON-DESTRUCTIVE METHODS

In marginal lands Opuntia ficus-indica (OFI) could be used as an alternative fruit and forage crop. The plant vigour and the biomass production were evaluated in Portuguese germplasm (15 individuals from 16 ecotypes) by non-destructive methods, 2 years following planting in a marginal soil and dryland conditions. Two Italian cultivars (Gialla and Bianca) were included in the study for comparison purposes. The biomass production and the plant vigour were estimated by measuring the cladodes number and area, and the fresh (FW) and dry weight (DW) per plant. We selected linear models by using the biometric data from 60 cladodes to predict the cladode area, the FW and the DW per plant. Among ecotypes, significant differences were found in the studied biomass-related parameters and several homogeneous groups were established. Four Portuguese ecotypes had higher biomass production than the others, 3.20 Mg ha−1 on average, a value not significantly different to the improved ‘Gialla’ cultivar, which averaged 3.87 Mg ha−1. Those ecotypes could be used to start a breeding program and to deploy material for animal feeding and fruit production.

Portuguese ecotypes of Opuntia ficus-indica differ in biomass production

The Opuntia ficus-indica (L.) Miller is a species from the Cactaceae family with the center of origin and domestication in central Mexico. This species introduction in the Iberia Peninsula occurred, probably, by the end of the 15th century, after the discovery of America, spreading later throughout the Mediterranean basin. In Portugal, O. ficus-indica is located, usually, with a typical ruderal behavior, at the edge of roads and paths. In Portugal, as in other Mediterranean regions, inlands areas are under severe draught during extensive summers, in particular, and global warming is expected to affect them deeply in the near future. O. ficus-indica, by its morpho-physiological characteristics and multiple economic uses, represent an alternative crop for those regions. Sixteen Portuguese O. ficus indica ecotypes and two ‘Italian’ cultivars ("Gialla" and "Bianca") were evaluated for plant vigor and biomass production, by nondestructive methods, in the two years following planting. Biomass production and plant vigor were measured by estimating cladode number, cladode area and fresh weight per plant. Linear models to predict the area of cladodes and fresh weight per plant were previously established using a biometric analysis of 180 cladodes. It was not possible to establish an accurate linear model for dry matter using non-destructive estimation. Significant differences were found among populations in the studied biomass-related parameters, and different groups were unfolded. A group of four Portuguese ecotypes outperformed in terms of biomass production, comparable with the “Gialla” cultivar. This group could be used to start a breeding program with the objective of deploy material for animal feeding, biomass and fruit production. Nevertheless, the ‘Gialla’ cultivar showed the best performance, achieving the highest biomass related parameters, not surprisingly for it is an improved plant material.