Vigour/tolerance trade‐off in cultivated sunflower (Helianthus annuus) response to salinity stress is linked to leaf elemental composition

Developing more stress‐tolerant crops will require greater knowledge of the physiological basis of stress tolerance. Here, we explore how biomass declines in response to salinity relate to leaf traits across 20 genotypes of cultivated sunflower (Helianthus annuus). Plant growth, leaf physiological traits and leaf elemental composition were assessed after 21 days of salinity treatments (0, 50, 100, 150 or 200 mM NaCl) in a greenhouse study. There was a trade‐off in performance such that vigorous genotypes, those with higher biomass at 0 mM NaCl, had both a larger absolute decrease and proportional decrease in biomass due to increased salinity. More vigorous genotypes at control were less tolerant to salinity. Contrary to expectation, genotypes with a low increase in leaf Na and decrease in K:Na were not better at maintaining biomass with increasing salinity. Rather, genotypes with a greater reduction in leaf S and K content were better at maintaining biomass at increased salinity. While we found an overall trade‐off between sunflower vigour and salt tolerance, some genotypes were more tolerant than expected. Further analysis of the traits and mechanisms underlying this trade‐off may allow us to breed these into high‐vigour genotypes in order to increase their salt tolerance.     

Local autonomy,national policy and global imperatives: sex work and HIV/AIDS in Cebu City,Philippines

This paper contributes to cultural critiques of AIDS prevention policies through examining debates about mandatory HIV blood screening for women in Cebu City’s sex industry during 1993. These debates were inspired by the Department of Health’s national policy to eliminate mandatory blood screening on the grounds that it was expensive and ineffectual in slowing the spread of HIV. While the rhetoric of the debate was influenced by the emerging ‘global discourse’ on HIV/AIDS and human rights, the debate itself was always about local perceptions of women in the sex industry and Cebu’s administrative autonomy. This paper highlights how various socio-spatial scales helped to constitute Cebu’s response to mandatory testing, while at the same time reproducing an exclusionary discourse which silenced the voices of women in Cebu’s sex industry.     

Older Chinese and Korean migrants' experiences of the first COVID-19 lockdown in Aotearoa New Zealand: A qualitative study

Later-life migrants, as older people living away from their home nations, occupy multiply-precarious positions in relation to national COVID-19 pandemic responses. Concern has particularly centred on this group's increased risk of social and linguistic exclusion. We explore the perspectives of later-life older Chinese and Koreans living in New Zealand during the nation's COVID-19 lockdown of 2020. This paper presents a sub-analysis of culturally-matched interviews conducted with 3 Korean and 5 Chinese later-life migrants. These participants are a sub-sample of a larger qualitative interview study comprising 44 interviews. A social capital approach has been used to aid conceptualisation of participants' experiences and a reflexive thematic approach guided analysis. Despite their underrepresentation in national response efforts, Chinese and Korean later-life migrants resourcefully participated in ethnically-specific pandemic initiatives. Three themes identified were: (1) taking it seriously (2) already digitally literate (3) challenges and difficulties. Older Asian migrants engaged in a range of creative strategies to stay connected during COVID-19 lockdowns which drew heavily on pre-existing social capital. Future pandemic responses should seek to improve connectedness between the national government COVID-19 response and older Korean and Chinese later-life migrants.     

Factors influencing the occurrence of fall armyworm parasitoids in Zambia

Journal of Pest Science - Invasive alien species have environmental, economic and social impacts, disproportionally threatening livelihood and food security of smallholder farmers in low- and...     

Drying and wetting of Mediterranean soils stimulates decomposition and carbon dioxide emission: the "Birch effect"

Observations on the net carbon exchange of forests in the European Mediterranean region, measured recently by the eddy covariance method, have revived interest in a phenomenon first characterized on agricultural and forest soils in East Africa in the 1950s and 1960s by H. F. Birch and now often referred to as the "Birch effect." When soils become dry during summer because of lack of rain, as is common in regions with Mediterranean climate, or are dried in the laboratory in controlled conditions, and are then rewetted by precipitation or irrigation, there is a burst of decomposition, mineralization and release of inorganic nitrogen and CO(2). In forests in Mediterranean climates in southern Europe, this effect has been observed with eddy covariance techniques and soil respiration chambers at the stand and small plot scales, respectively. Following the early work of Birch, laboratory incubations of soils at controlled temperatures and water contents have been used to characterize CO(2) release following the rewetting of dry soils. A simple empirical model based on laboratory incubations demonstrates that the amount of carbon mineralized over one year can be predicted from soil temperature and precipitation regime, provided that carbon lost as CO(2) is taken into account. We show that the amount of carbon returned to the atmosphere following soil rewetting can reduce significantly the annual net carbon gain by Mediterranean forests.     

Damage caused by the American grey squirrel (Sciurus carolinensis) to agricultural crops, poplar plantations and semi-natural woodland in Piedmont, Italy

The incidence of damage caused by grey squirrels in the Turinplain was studied to assess the impact this alien species ishaving on the highly fragmented Piedmont environment, in particularon profitable cereals, poplar plantations and semi-natural woodlands.The survey of damage was conducted both by interviews to localfarmers and growers and by direct assessment using the NearestNeighbour Method on plantations and woodlands, studying randomlychosen plots in the Turin plain to gain a general overview ofthe situation. The results show a low incidence of damage causedby grey squirrels in the area: little or none was found in semi-naturalwoodlands and in agricultural crops, apart from maize whereless than 1 per cent of fields showed damage, and poplar plantationswhere 5 per cent had signs of bark stripping. Damage on maizecrops was random across the plain, but debarking damage to poplarswas mostly concentrated on the western side of the plain, andtended to occur only in particular years. Damage was concentratedclose to streams and rivers surrounding fields and plantations.The introduction of the grey squirrel in Italy has already causedecological damage such as the extinction of the red squirrelin some areas. Nevertheless, little or no information is availableon the damage this species is causing on woodlands or agriculturalareas. This study is a preliminary survey in order to fill thisgap.     

油茶叶片相对电导率与其养分含量的关系

为探求提供一种简捷实用的林木养分测定方法.以油茶为对象,采用常规养分分析和电导率法,分别测定油茶叶片样品的N、P、K养分含量及其相对电导率,建立其相对电导率与养分含量的相关模型,并探索利用根据测定样品的电导率,来快速获得该样品的养分含量.结果表明,油茶叶片样品相对电导率与N、P、K养分含量相关性良好,且均遵循多项式拟合模型,经验证,该预测模型精度达90％以上.     

Seasonal fluctuations of starch in root and stem tissues of coppiced Salix viminalis plants grown under two nitrogen regimes

Seasonal changes in starch were studied at the tissue and cellular levels in roots and stems of Salix viminalis L. cuttings. Cuttings were planted in pots containing sand and grown in a controlled environment chamber in which seasons were artificially induced by changes in temperature and photoperiod. Nitrogen was supplied at optimum and low rates, and during dormancy, one-half of the plants were decapitated. Starch concentrations in root and stem tissues were determined regularly during shoot extension growth, dormancy and resprouting after dormancy. We used light microscopy (LM) combined with image analysis (IA) to determine the cellular localization and amount of starch in different cell types of stem and root tissues. Chemical analysis confirmed that starch concentrations were lower in plants receiving a high-N supply rate than in plants receiving a low-N supply rate. In all plants, the highest concentration of starch was in the roots. Light microscopy and IA showed that starch accumulated mainly in the phloem and cortical cells of both root and stem tissues. Starch grains were also regularly found in ray parenchyma cells. The amount of starch as well as the size of the grains showed strong seasonal fluctuations. In both roots and stems, starch concentrations were highest during predormancy and lowest during periods of shoot extension growth. At the time of resprouting, root cells of decapitated plants were more depleted of starch than root cells of intact plants, supporting the hypothesis that starch reserves in roots are important during the early phase of resprouting in coppice systems.     

Presence and viability of Ceratocystis lukuohia in ambrosia beetle frass from Rapid ʻŌhiʻa Death‐affected Metrosideros polymorpha trees on Hawaiʻi Island

Rapid ?ōhi?a Death (ROD) is a fungal disease of ?ōhi?a lehua (Myrtaceae: Metrosideros polymorpha) caused by Ceratocystis lukuohia and C. huliohia. ROD is the aetiological agent of widespread mortality of this important tree on Hawai?i Island, but its epidemiology remains unclear. We investigated the prevalence and viability of C. lukuohia in ambrosia beetle frass in ROD‐affected ?ōhi?a trees. A total of 200 frass traps were placed onto C. lukuohia‐infected ?ōhi?a at four locations on the east side of Hawai?i Island. Frass was collected and screened for the presence of C. lukuohia DNA using a diagnostic qPCR assay. In addition, frass samples were screened for viability by carrot baiting. All trapped beetles were of the genus Xyleborus, with the majority being the non‐native X. ferrugineus. Of the frass samples tested, 62% contained C. lukuohia DNA and 17% of carrot baits were positive for the fungus. These results indicate that ambrosia beetle frass releases C. lukuohia into the environment. We discuss the potential role infested frass could play in the ROD pathosystem.