Systematics of <i>Podocoma</i> (Asteraceae: Astereae): a generic reassessment

Podocoma is a southern South American genus of perennial herbs with short-radiate capitula with two- to four-seriate ray florets and a two- to three-seriate pappus of scabridulous setae. The ray florets have corollas with narrow limbs. The rostrate cypsela of Podocoma is one of the most distinct features of the genus. Podocoma, with many of the endemic southern South American genera of Astereae, is included in subtribe Podocominae. Podocoma traditionally contained seven mainly Brazilian species (P. asperrima, P. bellidifolia, P. blanchetiana, P. hieracifolia, P. hirsuta, P. regnellii and. P. spegazzinii), and its expansion to include two species of Conyza (C. notobellidiastrum and C. rivularis) was, perhaps, the most significant recent change in the generic concept of Podocoma. However, recent molecular- and morphology-based phylogenetic analyses do not support the inclusion of these two species in Podocoma. Morphological and anatomical studies were carried out in order to clarify the taxonomy of Podocoma and to delimit the genus and its species. On the basis of the results of these morphological and anatomical studies, and those from molecular- and morphology-based phylogenetic analyses, P. notobellidiastrum and P. rivularis are excluded from Podocoma and transferred to a new genus that is currently under description. Moreover, P. regnellii and P. asperrima are placed in synonymy with P. hirsuta and P. spegazzinii, respectively. Three species, P. bellidifolia, P. blanchetiana and P. hieracifolia, are recognized here as a complex of closely related species from a morphological point of view; however, they are treated separately.Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plat

Systematics of <i>Podocoma</i> (Asteraceae: Astereae): a generic reassessment

Podocoma is a southern South American genus of perennial herbs with short-radiate capitula with two- to four-seriate ray florets and a two- to three-seriate pappus of scabridulous setae. The ray florets have corollas with narrow limbs. The rostrate cypsela of Podocoma is one of the most distinct features of the genus. Podocoma, with many of the endemic southern South American genera of Astereae, is included in subtribe Podocominae. Podocoma traditionally contained seven mainly Brazilian species (P. asperrima, P. bellidifolia, P. blanchetiana, P. hieracifolia, P. hirsuta, P. regnellii and. P. spegazzinii), and its expansion to include two species of Conyza (C. notobellidiastrum and C. rivularis) was, perhaps, the most significant recent change in the generic concept of Podocoma. However, recent molecular- and morphology-based phylogenetic analyses do not support the inclusion of these two species in Podocoma. Morphological and anatomical studies were carried out in order to clarify the taxonomy of Podocoma and to delimit the genus and its species. On the basis of the results of these morphological and anatomical studies, and those from molecular- and morphology-based phylogenetic analyses, P. notobellidiastrum and P. rivularis are excluded from Podocoma and transferred to a new genus that is currently under description. Moreover, P. regnellii and P. asperrima are placed in synonymy with P. hirsuta and P. spegazzinii, respectively. Three species, P. bellidifolia, P. blanchetiana and P. hieracifolia, are recognized here as a complex of closely related species from a morphological point of view; however, they are treated separately.Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plat

Field-scale validation of an automated soil nitrate extraction and measurement system

One of the many gaps that needs to be solved by precision agriculture technologies is the availability of an economic, automated, on-the-go mapping system that can be used to obtain intensive and accurate ‘real-time’ data on the levels of nitrate nitrogen (NO3–N) in the soil. A soil nitrate mapping system (SNMS) has been developed to provide a way to collect such data. This study was done to provide extensive field-scale validation testing of the system’s nitrate extraction and measurement sub-unit (NEMS) in two crop (wheat and carrot) production systems. Field conditions included conventional tillage (CT) versus no tillage (NT), inorganic versus organic fertilizer application, four soil groups and three points in time throughout the season. Detailed data analysis showed that: (i) the level of agreement, as measured by root mean squared error (RMSE), mean absolute error (MAE) and coefficient of efficiency (CE), between NEMS soil NO3–N and standard laboratory soil NO3–N measurements was excellent; (ii) at the field-scale, there was little practical difference when using either integer or real number data processing; (iii) regression equations can be used to enable field measurements of soil NO3–N using the NEMS to be obtained with laboratory accuracy; (iv) future designs of the SNMS’s control system can continue to use cheaper integer chip technology for processing the nitrate ion-selective electrode (NO3 -–ISE) readings; and (v) future designs of the SNMS would not need a soil moisture sensor, ultimately saving on manufacturing costs of a more simple syste

Systematics of <i>Podocoma</i> (Asteraceae: Astereae): a generic reassessment

Podocoma is a southern South American genus of perennial herbs with short-radiate capitula with two- to four-seriate ray florets and a two- to three-seriate pappus of scabridulous setae. The ray florets have corollas with narrow limbs. The rostrate cypsela of Podocoma is one of the most distinct features of the genus. Podocoma, with many of the endemic southern South American genera of Astereae, is included in subtribe Podocominae. Podocoma traditionally contained seven mainly Brazilian species (P. asperrima, P. bellidifolia, P. blanchetiana, P. hieracifolia, P. hirsuta, P. regnellii and. P. spegazzinii), and its expansion to include two species of Conyza (C. notobellidiastrum and C. rivularis) was, perhaps, the most significant recent change in the generic concept of Podocoma. However, recent molecular- and morphology-based phylogenetic analyses do not support the inclusion of these two species in Podocoma. Morphological and anatomical studies were carried out in order to clarify the taxonomy of Podocoma and to delimit the genus and its species. On the basis of the results of these morphological and anatomical studies, and those from molecular- and morphology-based phylogenetic analyses, P. notobellidiastrum and P. rivularis are excluded from Podocoma and transferred to a new genus that is currently under description. Moreover, P. regnellii and P. asperrima are placed in synonymy with P. hirsuta and P. spegazzinii, respectively. Three species, P. bellidifolia, P. blanchetiana and P. hieracifolia, are recognized here as a complex of closely related species from a morphological point of view; however, they are treated separately.Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plat

Novos registros de espécies da subtribo Ecliptinae (Heliantheae - Asteraceae) para a Amazônia brasileira New records of species of the Ecliptinae subtribe (Heliantheae - Asteraceae) to the Brazilian Amazon

Sete espécies da subtribo Ecliptinae encontradas nos estados do Acre, Amapá, Amazonas, Pará e Rondônia, são apresentadas como novos registros para a Amazônia brasileira: Acmella uliginosa, Aspilia camporum, Aspilia ulei, Melanthera latifolia, Melanthera nivea, Spilanthes nervosa e Wedelia calycina. São apresentadas descrições e ilustrações para as espécies, dados sobre a distribuição geográfica, hábitat, época de floração e frutificação. Os novos registros evidenciam a importância de estudos sobre a flora amazônica e demonstram a necessidade de coletas mais intensas na região.<br>The following seven species of the subtribe Ecliptinae found in the states of Acre, Amapá, Amazonas, Pará and Rondônia have been recorded at the Brazilian Amazonia, for the first time: Acmella uliginosa, Aspilia camporum, Aspilia ulei, Melanthera latifolia, Melanthera nivea, Spilanthes nervosa and Wedelia calycina. Species descriptions and illustrations are presented, as well as information about geographic distribution, habitats and phenology. These new records highlight the importance of the floristic studies in Amazonia, and the need to carry out intensive fieldwork to improve the sampling in this region

Burkholderia phytofirmans sp. nov., a novel plant-associated bacterium with plant-beneficial properties

A Gram-negative, non-sporulating, rod-shaped, motile bacterium, with a single polar flagellum, designated strain PsJNT, was isolated from surface-sterilized onion roots. This isolate proved to be a highly effective plant-beneficial bacterium, and was able to establish rhizosphere and endophytic populations associated with various plants. Seven related strains were recovered from Dutch soils. Based on 16S rRNA gene sequence data, strain PsJNT and the Dutch strains were identified as representing a member of the genus Burkholderia, as they were closely related to Burkholderia fungorum (98·7 %) and Burkholderia phenazinium (98·5 %). Analysis of whole-cell protein profiles and DNA–DNA hybridization experiments confirmed that all eight strains belonged to a single species. Strain PsJNT had a DNA G+C content of 61·0 mol%. Only low levels of DNA–DNA hybridization to closely related species were found. Qualitative and quantitative differences in fatty acid composition between strain PsJNT and closely related species were identified. The predominant fatty acids in strain PsJNT were 16 : 0, 18 : 17c and summed feature 3 (comprising 16 : 17c and/or iso-15 : 0 2-OH). Isolate PsJNT showed high 1-aminocyclopropane-1-carboxylate deaminase activity and is therefore able to lower the ethylene level in a developing or stressed plant. Production of the quorum-sensing signal compound 3-hydroxy-C8-homoserine lactone was detected. Based on the results of this polyphasic taxonomic study, strain PsJNT and the seven Dutch isolates are considered to represent a single, novel species, for which the name Burkholderia phytofirmans sp. nov. is proposed. The type strain is strain PsJNT (=LMG 22146T=CCUG 49060T).