Prickly Pear Species Research Articles

A Comparative Analysis of Morphological Characteristics between Endangered Local Prickly Pear and the Newly Introduced Dactylopius opuntiae-Resistant Species in Eastern Morocco.

Prickly pear serves as a significant source of income for farmers worldwide, with production taking place in temperate, subtropical, and cold regions. The objective of the present investigation is to explore the morphological parameters of Opuntia robusta and Opuntia dillenii which are resistant to the white cochineal (Dactylopius opuntiae), as well as the local prickly pear that is currently threatened with extinction. This investigation aims to evaluate the feasibility of replacing the endangered local prickly pear with the recently introduced species O. robusta and O. dillenii. This analysis is based on a comprehensive assessment of 26 qualitative and 25 quantitative traits pertaining to cladodes and fruits. In terms of species differentiation and the selection of discriminative features, this study demonstrates the effectiveness of various statistical methods, as well as the analysis carried out according to the descriptors recommended by the International Union for the Protection of New Varieties of Plants (UPOV). Of the 51 parameters evaluated, 13 qualitative and 23 quantitative characters are significant in differentiating the species under study. This underscores the importance of quantitative traits in distinguishing different prickly pear species. Furthermore, color is identified as a crucial characteristic for discriminating between the studied samples. O. robusta is characterized by its high fruit weight, large size, greater pulp content, and high pulp-to-peel ratio, all of which are desirable traits for fresh consumption. Additionally, O. robusta has the highest number of fully developed seeds, making it an attractive option for use in the cosmetic industry. This characteristic renders the O. robusta a potential substitute for the endangered ecotype . However, O. robusta is distinguished by its short stalk, which poses a challenge for fruit harvesting and leaves it susceptible to physical damage and quality loss. Conversely, O. dillenii displays a low pulp content, which serves as a critical indicator of fruit quality. The only desirable agronomic trait of this species is its elevated seed content, which has the potential for utilization in oil production for the cosmetic industry.

Comparative Assessment of Physical and Chemical Characteristics of Prickly Pear Seed Oil from Opuntia ficus-indica and Opuntia megacantha Varieties

The prickly pear (Opuntia spp.) is an important plant in the economies of arid and semiarid areas, considering its low agronomic requirements and high water use efficiency. Characterizing the chemical composition of this plant will open new avenues for food, pharmaceutical, and cosmetic applications. In this context, this study examined the physical and chemical parameters of fruit seed oils of two prickly pear species from Rhamna area located in the center of Morocco: Opuntia ficus-indica (OFI), represented by the varieties “Safra” and “Aakria,” and Opuntia megacantha (OM), represented by the variety “Derbana.” The evaluated parameters included oil content, free acidity, specific extinction coefficients (K232 and K270), pigment content, fatty acid, and triglyceride composition. The seed oil contents of the three varieties “Safra,” “Aakria,” and “Derbana” were 8.09%, 8.74%, and 8.04%, respectively. OM (“Derbana”) seed oil was the most stable. The three studied varieties had higher contents of α-pheophytin and carotenoids than that of chlorophyll. Oil from the “Aakria” variety was distinguished by having the highest contents of α-pheophytin and chlorophyll. Significant differences in some fatty acid and triglyceride contents were noted. The major fatty acids of the three varieties were linoleic acid (60.55%–63.46%), followed by oleic acid (18.88%–21.81%) and palmitic acid (13.03%–13.75%). Furthermore, the chromatographic profiles of the triglycerides have shown the dominance of trilinolein (LLL, 24.33%–26.49%) and oleoyl-dilinoleoyl-glycerol (OLL, 20.92%–21.92%). Some triglycerides could be considered species markers, especially OLL, dipalmitoyl-linoleoyl-glycerol (PPL), oleoyl-linoleoyl-linolenoyl-glycerol and palmitoyl-oleoyl-dilinoleoyl-glycerol fraction (OLLn + PoLL), and stearoyl-dioleoyl-glycerol (SOO). This study provides a basis for qualitatively evaluating the therapeutic and cosmetic potential of prickly pear derivatives and for establishing quality standards of seed oil derived from the two species studied.

Antioxidant Activity Analysis of <i>Opuntia</i> Species as Influenced by Season and Plant Parts

The prickly pear cactus (Opuntia), native to Mexico, has grown in popularity and is locally grown and adapted on Jeju Island. The fruits of this cactus species are in particular widely employed as raw materials, which are then processed into various food and medicinal items, including chocolates and vitamins, for purposes of human consumption. Because this crop has been dubbed one of Jeju’s iconic agricultural crops, research studies elucidating the prickly pear cactus’ medicinal properties, including antioxidant activity, of this particular plant and related cultivated species have demonstrated high value to the scientific community. Currently, consumers do not purchase products f or c onsumption a lone, but in a ddition f or t heir added health benef its. The present study in particular honed in on two species of prickly pear cactus that are cultivated on Jeju Island which include: ‘Baeknyeoncho’ (Opuntia ficus-indica) and ‘Cheonnyeoncho’ (Opuntia humifusa). From these species, s pecif ci p lant p arts i ncluding t he f lower, mature and y oung stems, roots, a nd f ruit w ere subjected to further antioxidant analysis, which included the determination of polyphenol, flavonoid, DPPH radical, ABTS radical, and anthocyanin levels. These particular antioxidants were determined during two seasons, over the course of the summer and winter. Results revealed that the antioxidant activity for both species was more active during the summer season. Antioxidant levels occurred at the highest rates within t he flowers o f the c actus plants. However, of significant note was that the cactus stem, in both mature and young plants, possessed higher antioxidant activity compared to those of the fruit that is currently employed for commercial purposes.

Beyond endemism, expanding conservation efforts: What can new distribution records reveal?

Geographical range is one of the critical features for species conservation assessment. Nevertheless, species distribution is frequently unknown, undervalued or overlooked. During a broad taxonomic and floristic study of the southern South American prickly pear species (Opuntia spp.), new records of a species previously considered endemic to Argentina have been found in Uruguay and Brazil. Molecular phylogenetic inference was carried out to further evaluate the identity of the new records, and ecological niche models were implemented to test how the new records would fit in the previous known distribution of the species. Through molecular and morphological evidence, we confirmed the new records of Opuntia bonaerensis for Brazilian and Uruguayan floras and discussed its phylogenetic relationship and morphological similarities with closely related species. Our new records uncovered a distribution pattern congruent with the Neotropical Peripampasic Orogenic Arc, which must be further explored to better determine the biogeographic history of the species. Ecological niche models (ENM) revealed that O. bonaerensis likely had a putative ancient distribution across the grasslands and shrublands in the Pampean region largely congruent with the populations found in Brazil and Uruguay, suggesting relictual Pleistocene populations of the species and the role of glacial/interglacial cycles on the distribution of the species. In a prospective climate change scenario, ENM suggests that the species would in general be more restricted to the southernmost limits of the Pampa region and previous outlying records from Mendoza (Argentina) are a putative future refuge for O. bonaerensis. The importance of these new records for biodiversity and conservation assessment efforts that are ongoing at different scales in Brazil and neighboring areas is highlighted.

Morfología de semillas de siete especies del género Opuntia (Cactaceae) del sureste de Coahuila (México)

Introducción y Objetivos: Opuntia se distribuye naturalmente desde Canadá hasta Argentina, actualmente forma parte del paisaje en algunas regiones del mundo, comprende entre 191 y 215 especies; la conservación ex situ de este recurso fitogenético ha adquirido relevancia, pero la identificación de especies por semilla es una limitante cuando no se tienen caracteres morfológicos confiables. El objetivo del estudio fue caracterizar la morfología de semillas de siete especies de Opuntia e identificar caracteres morfológicos propios, para tener un criterio en la identificación de especies cuando el material vegetal conservado es semilla. M&M: Mediante la técnica de desgaste y análisis de imágenes se evaluó: grosor de testa (GT), grosor de la cubierta funicular ventral (GCFV), longitud del embrión (LE), área del embrión (AE), longitud del eje mayor (LEMA) y del eje menor (LEME). Por medio de ANDEVA exploratorios y componentes principales (CP) se detectaron los caracteres más sobresalientes. Para la clasificación y predicción de especies se realizó un análisis supervisado con los métodos K-NN y LDA.
 Resultados: Las diferencias en todas las variables entre especies fueron significativas. Opuntia ficus-indica presentó semillas de mayor tamaño. Las variables que más ayudan a discriminar son GCFV y GT. El análisis de componentes principales explicó el 92% de la variación total. El método de predicción K-NN, fue capaz de predecir correctamente el 83% de los casos en la clasificación de las especies.
 Conclusiones: Los caracteres de semillas evaluados, principalmente el GCFV y GT, pueden coadyuvar en la descripción morfológica de las especies de nopal o o en identificación de especies de Opuntia cuando sólo se tiene semilla.

Empirical models in the description of prickly pear shoot (Nopal) drying kinetics

ABSTRACT The objective of this study was to describe the technological process involved in the drying kinetics of fresh-cut prickly pear shoots through numerical and analytical solutions. Shoots of two different prickly pear species were used, ‘Gigante’ and ‘Miúda’. Drying was performed at different temperatures (50, 60, 70 and 80 °C) and weighing procedures were made continuously. The experimental data were expressed as moisture ratio. The Page model showed the best fit to the drying kinetics of minimally processed ‘Gigante’ and ‘Miúda’ prickly pear shoots, with the best coefficients of determination and Chi-square. Peleg and Wang & Singh models can not be used to simulate the drying of ‘Gigante’ and ‘Miúda’ prickly pear shoots within the evaluated range of temperatures, showing an incoherent graphic pattern.

PRINCIPAL COMPONENTS OF THE INTENSITY OF SQUAMOUS ROT ON PRICKLY PEAR PLANTATIONS IN THE SEMIARID REGION OF THE STATE OF PARAÍBA, BRAZIL

ABSTRACT The aim of the present study was to identify fungal pathogens associated with prickly pear rot and the main components of squamous rot on plantations in the semiarid region of the state of Paraíba, Brazil. Pathogens were identified morphologically. The determination of the main components of squamous rot intensity was based on the incidence and severity of the disease. Fifteen genera of fungi were associated with rot, including Scytalidium sp., which was found on all plantations. The analyses indicated that relative humidity and rainfall favored the intensity of rot more than temperature. At least three pathogens were found to be associated with a high incidence of rot in prickly pear species in the semiarid region of the state of Paraíba, Brazil, but Scytalidium sp. was the most widely distributed. Moreover, the disease caused by this fungus intensifies and progresses under conditions of high humidity at moderate temperatures.

Characterization of two prickly pear species flowers growing in Tunisia at four flowering stages

Opuntia flowers belonging to two species of prickly pear were evaluated at four flowering stages: vegetative, initial flowering, full flowering and post-flowering stage, for possible use as a potential source in the food enrichment. Chemical composition including moisture, ash, protein, fat, soluble sugars, total fibers, mineral amounts and fatty acid profiles of Opuntia ficus-indica and Opuntia stricta flowers were investigated. Functional properties (swelling capacity (SWC), water holding capacity (WHC), water solubility index (WSI) and oil holding capacity (OHC)) were also studied. Results showed that during the maturation of flowers, there is a decrease in protein contents whereas fat contents increase, for both species. High minerals amounts were noticed in Opuntia flowers and they can be considered as an excellent source of minerals. The fatty acids profiles were dominated by the palmitic acid (38–59%). The techno-functional properties (SWC, WSI, WHC and OHC) were found to be important and they can be modulated according to the temperatures. Owing to its chemical profile and functional properties, Opuntia flowers could be used as an ingredient to improve different physical and nutritional properties of foods.

Prickly Pear Conversation

Some love it as a plant they know in its proper habitat-a native plant in deserts of North and South America, or as a crop for the cultivation of cochineal insects for their red dye, or simply as an exotic potted plant that is carefully tended in climates unsuitable for its growth. In many countries around the world it is hated as a weed- a plant that can grow uncontrollably fast in places where it has been imported.Prickly pear plants are made up of pads joined together, which are actually flattened stems. The only leaves are small, short-lived fingers that cover the new, expanding pads in spring. Scattered over the mature pads are areoles from which long spines, and fine brown bristles, or glochids, grow. Each areole is also a growing point from which a new pad, flower, or root can develop. Any pad broken off and allowed to lie on the ground will put down roots when it rains and soon become a new plant. In this way prickly pear can spread fast.I sat one November day in Montrose Canyon near Tucson. It had been hot and dry for months. The pads of prickly pear were thin and wrinkly; diamond shapes between spines, rows of ridges like ripples on a sand bar. They looked old, for surely wrinkled means old. But they were mostly not old. With winter rain they would swell and fatten, swell out and become smooth with no sign of wrinkles. Not many living things rejuvenate themselves like cactus pads, though they cannot regain the tiny little pinky-green fat fingers that were leaves. I thought how, inside those wrinkled pads, there was still moisture, waiting, storing life inside those wrinkled green skins, and marveled at the adaptation to drought conditions that occur in southern Arizona before and after the short-lived summer rains.Although there are hundreds of species of prickly pear, varying from miniature plants to trees one hundred feet tall, the common ones are wide, spreading shrubs about four feet high, with their pale, gray-green rounded pads about nine inches long. The Englemann's prickly pear (Opuntia englemannii) is one of the commonest, with its long white spines and rusty colored glochids. Looking across the sun-bright desert of Arizona, patches of round, clumped pads in their faded watercolor-green, between giant saguaros and Palo Verde trees, is the classic Sonoran desert scene. Or, looking at a steep rocky slope from a distance, one sees, between the giant saguaros, the regular patches of rounded pads, their smooth hard surfaces reflecting sunlight at different angles, those in shade enhancing the green of their sunlit neighbors by their contrast. No other place in the world resembles the deserts of southwest North America.It rains. The muted greens of cactus plants seem brighter without sun and drops roll off the prickly pear pads to darken the desert pan. Moisture causes the strange fragrance of creosote bushes to pervade the atmosphere. Cottontail rabbits have taken cover and no birds sing. Rain is such an event in the desert, and through the melancholy air I watch the gentle fall of contentment. This winter rain will make a colorful spring. The pads of prickly pear are swelling, the wrinkles of drought ironing out as the masses of fine roots absorb water. Those fine roots take up the merest suggestion of water, roots that hold together the thin layer of desert soil.From every window of my house here in the Sonoran desert I see Englemann's prickly pear. As far as I can see this is the most common plant, though patches of different cacti, bur-sage, and creosote bush are intermingled, along with a wide variety of less common desert plants. The diversity is remarkable to me after having known the Sahara, where the few plants species are scattered and rare. And with this rain, the seed bank in the soil will sprout dozens more species that wait for a little more warmth to grow up and flower.How much the prickly pear will grow in the spring and how many flowers develop depends on how much rain we get this winter, and I think of April when the young soft pads swell out-the soft, bright green nopales that provide a vegetable for many, especially Native Americans. …

Genetic differentiation of island populations: geographical barrier or a host switch?

••, ••, ••, ••, •• ••, •• In the Sonoran desert, there exists a diverse community of cactophilic drosophilids that exploit toxic, rotting cactus tissue as a food resource. The chemistry of the necrotic cactus tissue varies among species, and several drosphilid species have evolved specialized detoxification mechanisms and a preference for certain cactus types. In the present study, we compared the genetic structure of two columnar cactus species,Drosophila mettleriandDrosophila mojavensis, and two prickly pear species,Drosophila mainlandiandDrosophila hamatofila, which have all recently colonized Catalina Island off the coast of southern California. Because there are no columnar cactus species on Catalina Island, the two columnar specialists underwent a host switch to prickly pear cactus, the only cactus present on the island. Previous genetic studies ofD. mettleriandD. mojavensisshowed significant genetic differentiation between mainland and island populations, which could result from restricted gene flow as a result of the San Pedro Channel, or because of a host switch to prickly pear. To distinguish between these possibilities, we analyzed the genetic structure of the prickly pear species aiming to isolate the effects of geography versus host switching. The results obtained show little to no genetic differentiation for the prickly pear species, supporting the hypothesis that the genetic differentiation of the two columnar species is a result of a host switch from columnar cacti to prickly pear. © 2012 The Linnean Society of London,Biological Journal of the Linnean Society, 2012,••,

Variation in chemical composition and biological activities of two species of Opuntia flowers at four stages of flowering

The chemical composition of hexane extracts from flowers belonging to two species of prickly pear, Opuntia ficus-indica (L.) Miller and Opuntia stricta (Haw.) Haworth has been studied by gas chromatography–mass spectrometry in four developmental stages of flower: vegetative, initial flowering, full flowering, and post-flowering stages. Remarkable differences were noted between the flowers’ compositions. The main compounds were carboxylic acid (28–97%), terpenes (0.2–57%), esters (0.2–27%), and alcohols (<1.8%).The study of the biological activities showed that extracts were active in vitro towards four bacteria and two fungal strains. It exhibited remarkable activity against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli.Antioxidant activity of the flowers extracts was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical method.Our findings demonstrate the interest of Opuntia flowers extract as a source of bioactive substances and its potential preservative use in food.

Chemical characterization of Opuntia dillenii and Opuntia ficus indica fruits

The chemical compositions (moisture, °Brix, total fibre, protein, fat, ash, pH, acidity, ascorbic acid, total phenolics, Na, K, Ca, Mg, Fe, Cu, Zn, Mn, Ni and Cr) were determined in fruits belonging to two species of prickly pear, Opuntia ficus indica and Opuntia dillenii, from Tenerife Island. The chemical compositions of the two species were clearly different. However, no important differences were observed between orange and green prickly pears within the specie O. ficus indica. An important contribution to the intakes of fibre, ascorbic acid, Mn, Cr and total phenolics is provided by the consumption of prickly pears, particularly from fruits of O. dillenii. Applying factor and/or discriminant analysis, the prickly pear samples were differentiated according to the species, altitude and region of cultivation in the island.

Biochemical and Nutritional Characterization of Three Prickly Pear Species with Different Ripening Behavior

Biochemical and nutritional changes were studied during the ripening process of three Opuntia morphospecies with different ripening behavior: Naranjona (O. ficus-indica), Blanca Cristalina (Opuntia sp.), and Esmeralda (Opuntia sp.) of early, early-intermediate, and intermediate-late ripening, respectively. In loss of fresh weight, Naranjona showed the highest values, while in Blanca Cristalina and Esmeralda, a discrete weight loss was found. No significant differences were found among morphospecies in soluble solids, total titratable acidity and pH during the postharvest days. Blanca Cristalina and Esmeralda showed an increase in the content of carotenoids, while these diminished in Naranjona. The cell wall enzymes evaluated showed particular behaviors during the ripening of each morphospecies suggesting a fine biochemical control and not a clear relationship between fruit softening and enzyme activity. This study provides basic information on prickly pear ripening, in order to understand this process for its control and for improving shelf life.

Fatty acid composition and rheological behaviour of prickly pear seed oils

Prickly pear fruits constituted valuable foodstuff for humans and animals in arid and semi-arid regions. Two species of prickly pear from Tunisia, Opuntia ficus indica and Opuntia stricta, were investigated for fatty acid composition and physicochemical parameters of the seed oil. No significant difference in either physical or chemical parameters was found between the species. The main fatty acids of prickly pear seed oil were C16:0, C18:0, C18:1, C18:2. With an exceptional level of linoleic acid, up to 70%, the content of unsaturated fatty acids was high, at 88.5% and 88.0% for O. ficus indica and O. stricta, respectively. Rheological properties were analysed with changes of temperature and shear stress. Variations of viscosity were measured and the viscoelastic parameters were determined during heating and cooling cycles between 20 and 70 °C. Curves of flow were established with up and down cycles of shear stress at different temperatures. These measures highlighted the presence of large aggregates of crystal fatty acids in both Opuntia crude oils. Shearing and temperature destroyed this structural state and gave birth to an homogeneous stable suspension. The structural state of crude oil was confirmed using a contrast phase microscope, and the particle size distribution was obtained by laser granulometry.

Caracterización anatómica y conductividad hidráulica teórica de los elementos de vaso de variedades silvestres y cultivadas de nopal tunero (Opuntia)

Se estudió la morfología y la conductancia hidráulica teórica de elementos de vaso del xilema en cladodios de especies y variedades cultivadas y silvestres de nopal (Opuntia spp.) colectados en las regiones semiáridas de los estados de Jalisco y Zacatecas, con el fin de investigar si las diferencias en la resistencia a la sequía que se observan comúnmente en el campo entre especies silvestres y cultivadas de Opuntia pueden estar relacionadas con divergencias en la densidad, la anatomía de los vasos y en la conductividad hidráulica. Adicionalmente se investigó si existen diferencias en el grado de especialización del xilema entre variedades cultivadas y silvestres. Nuestras observaciones mostraron que en la especie cultivada Opuntia ficus-indica (L.) Mill. (variedades amarilla montesa, picochulo, chapeada, pelón liso, burrona y cristalina), así como en las silvestres O. streptacantha Lem. (variedades cardón y charola), O. robusta Wendl. (variedades tapón y tapón de mayo) y O. cochinera Griff., es más frecuente encontrar elementos de vaso con engrosamientos escalariformes y alternos, que los provistos de engrosamientos helicoidales. Las plantas estudiadas no mostraron diferencias morfológicas que indicaran un mayor grado de especialización en las características morfológicas registradas en los elementos de vaso. Los caracteres morfológicos de los elementos de vaso, y los de conductividad hidráulica, no revelan diferencias que puedan ayudar a explicar la mayor resistencia a la sequía en las especies silvestres de nopal en comparación con las cultivadas.

Potential Non-target Effects of a Biological Control Agent, Prickly Pear Moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), in North America, and Possible Management Actions

Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), the poster child of biological control, has recently invaded the United States. The first US record was at Big Pine Key, Florida, in 1989. Since then it has moved rapidly northward into South Carolina. Fears are high that it will disperse, either on its own, or with human help, into the US desert southwest and Mexico. There are at least 31 species of prickly pear in the US that are likely to be attacked by Cactoblastis and 56 species in Mexico. As well as the threat to wild cacti, there are over 250,000 ha of Opuntia plantations in Mexico that support a thriving agricultural industry, most of which is centered on harvesting fruits or pads. Possible control measures include classical biological control using parasitoids or pathogens from South America, chemical control or F1 sterility, as has been used successfully for the codling moth. However, most of these options appear to have insurmountable difficulties. Classical biological control raises the fear of further non-target effects of natural enemies on native cactus herbivores. Chemical control has potential non-target effects on other (rare) insects and is expensive. F1 sterility is also expensive and is not self-sustaining, requiring considerable and continual human input. Nevertheless, research on control options is vital as is further work on the rate of spread and impact of Cactoblastis in the United States Southeast, so that we can be as well prepared as possible to deal with this threat when it arrives in Arizona, California, and Mexico.

Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America: A Workshop of Assessment and Planning

The cactus moth, Cactoblastis cactorum Berg (Lepidoptera: Pyralidae), has been an important biological control agent of introduced and weedy prickly pear cacti (Opuntia spp., Cactaceae) in many parts of the world. Cactoblastis, a native of Argentina, was introduced into the Caribbean in 1957 to control weedy, but native species of prickly pear infesting rangeland. It has spread through the Caribbean and in 1989 was first found in Florida. It has now spread as far north as coastal Georgia. There is a continuous distribution of acceptable host species of Opuntia from southern Florida across the southern United States to the Pacific Coast. Mexico is a center of endemism and has many species of Opuntia. Prickly pear cacti constitute a highly important and uniquely desert-adapted subsistence food and cash crop in Mexico. Prickly pears have other valuable uses, such as in the production of cochineal dye and in desert landscaping. Because Cactoblastis readily attacks many novel hosts within Opuntia, it will likely have serious impacts on the ecology of desert environments and on the agricultural and horticultural uses of prickly pears. Further, if Cactoblastis does result in significant damage, it is likely to serve as another source of criticism of classical biological control. Cactoblastis cactorum in North America, A Workshop of Assessment and Planning, was held in Tampa, Florida in September 2000. Major subject areas covered include the biology and economic importance of Opuntia, the biology, biological control history, and current status of Cactoblastis, and potential methods of controlling Cactoblastis in North America. This paper summarizes findings of the workshop and provides an introduction to the workshop proceedings.

Prickly Pear Menace in Eastern Australia 1880-1940

Prickly Pear Menace in Eastern Australia 1880-1940

Growth and compositional changes during the development of prickly pear fruit

Growth and compositional changes in prickly pear (Opuntia spp.) fruit during the development of four species (O. ficus-indica, O. inermis, O. hyptiacantha and O. lind- heimeri) were studied. The weight and size of fruits belonging to O. ficus-indica, O. hyptiacantha and O. lindheimeri generally followed a single sigmoid growth pattern while fruits belonging to O. inermis followed a double sigmoid growth pattern. In all species, soluble solids and ascorbic acid contents increased with a concomitant decrease in titrat- able acidity as fruits matured. O. hyptiacantha consistently had the highest soluble solids and ascorbic acid contents and the lowest titratable acidity while O. lindeimeri consistently had the lowest soluble solids and ascorbic acid contents and highest titratable acidity throughout ontogeny. Although significant differences in soluble solids and ascorbic acid contents were observed, all four prickly pear species exhibited similar trends in compositional changes with growth. Attributes that ...

Herbicidal Control of Pricklypear Cactus in Western Texas

The recommended practice for pricklypear (Opuntia spp.) control in western Texas has been aerial spraying with a 1:1 mixture of 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] and picloram (4amino-3,5,6-trichloro-2-pyridinecarboxylic acid) at 0.56 kg/ha in late spring-early summer. This practice did not consistently control pricklypear. Experiments were conducted at 2 locations to determine if efficacy of the herbicide mixture could be improved by increasing the rate or by spraying at night. The herbicide mixture was applied at 0.56 and 1.12 kg/ha to dense pricklypear stands in morning and near midnight in December, June, August, and October. The high rate killed more Lindheimer pricklypear (0. lindheineri) and Edwards pricklypear (0. edwardsii) growing on clay loam soils compared to the low rate during most seasons. The higher rate did not increase control of hybrid pricklypear growing on clay soils sufficiently to justify the added treatment cost or to satisfy the management objectives of most ranchers. Night treatments killed significantly more pricklypear than daytime treatments only during late spring-early summer. The pricklypear species and hybrids were most susceptible to herbicide applications in late summer and early autumn and least susceptible to those in late spring-early summer. The efficacy of early winter treatments was intermediate.