Perspectives on the use of a seaweed extract to moderate the negative effects of alternate bearing in apple trees

Summary

Alternate bearing is a serious problem in many apple varieties. In fact, each year, apple trees have to be thinned in order to ensure a correct and constant balance between the reproductive and vegetative tendencies of the plant. In organic fruit growing, there is no alternative to the expensive and time-consuming process of hand-thinning. Under these conditions, the use of natural bio-stimulants which enhance the efficiency of nutrient uptake, plant fitness to different pedoclimatic conditions, and plant tolerance to stress, offers new opportunities to reduce the negative effects of alternate bearing. The aim of this work was to evaluate the effects of Actiwave^®, a metabolic enhancer derived from the alga, Ascophillum nodosum, on ‘Fuji’ apple trees affected by experimentally-imposed alternate bearing. The experiments were carried in open field conditions over four consecutive years. Although the effect of Actiwave^® was erratic from year-to-year, the compound generally reduced those problems linked to alternate bearing. Actiwave^® had its most significant effect on alternate bearing plants that were also affected by nutrient deprivation due to the absence of fertilisation. In these trees,Actiwave^® decreased the oscillations in yield between “on” and “off” years and increased the average fruit weight on plants affected by too-high a crop load. Treated trees also showed higher leaf chlorophyll contents (increased by 12%), with a consequent increase in the rates of photosynthesis and respiration. On the other hand, under standard conditions, in well-fertilised balanced plants, Actiwave^® did not have any significant effect. This evidence corroborates the hypothesis that Actiwave^® may be a useful tool to reduce alternate bearing in organic and low-input farming.     

Microbial properties of rhizosphere soils as affected by rotation,grafting, and soil sterilization in intensive vegetable production systems

The increased use of rotation, grafting, and soil sterilization has been documented to increase crop yield in intensive vegetable production systems in China. It is believed that these practices can promote changes in the rhizosphere that enhance early growth of plants. A 2-year greenhouse experiment on tomato double-cropping systems was conducted to investigate the effects of different agricultural treatments on microbial properties of rhizosphere soils and tomato fruit yield. The treatments included planting of welsh onion as a cover crop in the summer fallow (SF) period (CW), rotating vegetable chrysanthemum and tomato (CT), planting graft-tomato instead of auto-root tomato (GT), sterilizing soil with calcium cyanamide in the SF period (TC), and fallowing in the SF period (Control). Microbial population was analyzed by dilution plating. In general, microbial populations were higher in CT, GT and TC than in control. Fungal population was higher in TC whereas a high number of bacteria were found in CT. Soil microbial biomass C and N, total microbial population, organic C and total N showed significant positive correlations (P ≤ 0.01) with each others, and tomato yield showed significant positive correlations (P ≤ 0.05) with organic C, total N and total microbial population. In most treatments, CW, GT and TC significantly (P ≤ 0.05) increased tomato yield by 8%, 21% and 19% in four growing seasons, respectively. CT significantly (P ≤ 0.05) increased tomato yield by 26% in the spring season of 2007. These results suggested that rotation, grafting and soil sterilization could lead to changes in the microbial properties of plant rhizosphere and consequently increase plant yield. Additionally, the responses of plant yield were complex dependent on rhizosphere soil microbes in rotation-, grafting-, and soil sterilization-induced systems.     

Planting density for grafted melon as an alternative to methyl bromide use in Mexico

One of the major challenges of melon (Cucumis melo L.) yield is the decrease of fruit yield and quality caused by soil diseases. Soil disinfection with methyl bromide (MB) has been used to prevent soil-borne diseases damage; however, use of MB is being restricted because this substance damages the ozone layer. Searching for new MB alternatives, field experiments were carried out in open fields in soils infested with Fusarium oxysporum f. sp. melonis, Olpidium bornovanus, and Melon Necrotic Spot Virus (MNSV) in Colima, Mexico, where melons had only been grown previously using soil fumigation with MB. Yield and quality of melon cultivar Cruiser F1 (Harris Moran seed company) grafted on two rootstocks of Cucurbita maxima Duchesne × Cucurbita moschata Duchesne (“RS841”; Séminis seed company and “Shintosa Camelforce”; Nunhens seed company) were evaluated during two consecutive years. Each experiment had five treatments, two of which with non-grafted plants at a density of 18,519 plants/ha, with and without MB fumigation. The other three treatments consisted of grafted plants in non-fumigated soil with plant densities of 14,815, 11,111, and 9260 plants/ha. The use of melon grafted on “RS841” and “Shintosa Camelforce” rootstocks significantly increased the average fruit weight and the total yield of melons in soil without the need for MB. Grafting may be considered an alternative to MB fumigation. With the use of grafted melon plants, planting density may be reduced by 60%, obtaining higher yields than those obtained from non-grafted plants grown on fumigated land. Fruits harvested from grafted plants had equal firmness than those harvested from non-grafted plants, without affecting the content of soluble solids.     

植物根际促生菌在瓜菜工厂化育苗中的应用技术研究进展

植物根际微生态环境对于根系的健康发育、植株的茁壮生长意义重大。在瓜菜工厂化育苗过程中,幼苗根系生长空间小,持水保肥能力弱,微生态环境差,目前国内外相关学者的研究热点逐渐聚焦在通过接种植物根际促生菌或添加微生物有机肥来调控瓜菜幼苗根际微生物群落结构和多样性,以期达到活化养分、防控病害、促进幼苗生长的目的。笔者阐述了植物根际微生物的作用及其在瓜菜工厂化育苗中的应用技术研究进展。     

A novel use of the lacunarity index to discern landscape function

Discerning the function of a landscape involves comparing landscape use with spatial patterns. To do this requires both quantification of landscape use and landscape pattern and a means of comparing the two. An index of lacunarity has been used to quantify spatial pattern (specifically, habitat contagion). We demonstrate a new way of using the lacunarity index to quantify landscape function as well. We calculated lacunarity to describe landscape patchiness of experimental landscapes with respect to patterns of habitat and non-habitat areas (the previous use of lacunarity) as well as to describe patterns of patch use by animals in those landscapes, irrespective of habitat-patch patterns (a novel application of lacunarity). We demonstrate a disparity between landscape pattern and landscape use. This finding suggests that drawing generalizations of, and making predictions about, how animals respond to landscape spatial structure may not be straightforward.     

A landscape-geochemical approach in insular studies as exemplified by islets of the eastern Baltic Sea

The main objective of our investigations is to find out the primary geochemical properties of insular landscapes in order to ascertain the landscape stability on an area of land uplifting in the conditions of a regressive sea. Therefore we focus our study on the landscapes of Kolga Bay islets, which are located near the Estonian coast in the Gulf of Finland. A landscape-geochemical approach of landscape study improves the mapping of insular landscapes and understanding of processes of landscape development. Besides land use changes, land uplift and marine influence shape the landscape patterns of island through topography and subsurface water. We propose geochemical typology of landscapes based on substance movement (eluvial, superwatery, subwatery), field studies on islands, and chemical analysis of soil and water samples. From a landscape geochemical perspective, types of matter fluxes mainly control stability of an insular landscape. Interactions between geochemical, ecosystem and geomorphic processes reveal that islands behave as systems, rather than merely a sequence of interdependent soil-vegetation complexes along topographic gradients. This revised version was published online in August 2006 with corrections to the Cover Date.     

The designation of a historical site to maintain plant diversity in the Tokyo metropolitan region

Although urban habitats contribute to the conservation of species diversity, urbanization has significantly reduced biodiversity by causing environmental changes such as habitat loss and fragmentation. Therefore, research on urban biodiversity studies has become increasingly important. Historical heritage sites are recognized as important habitats in remnant green spaces in urban areas. We aimed to evaluate the role of historical sites in conserving biodiversity in urban areas. As the land in these historical sites is not modified, they have the potential to conserve biodiversity through continued maintenance activities such as mowing and tree cutting. In Japan, Tamagawa-josui, a waterway that runs from west to east through the Tokyo megacity (35° 40′ N, 139° 25′ E), has been recognized as a civil engineering heritage landmark that preserves water utilization technology from the early modern period (1600s, Edo-era). The present study examined the relationships between plant diversity and green space in a historic site of a megacity (i.e., Tamagawa-josui) and determined the factors that influence plant diversity. Specifically, we examined the relationships between plant species indices (species richness and species compositions) and environmental factors (management, environmental conditions, and landscape factors). The present study analyzed spatial changes in the plant species composition in Tamagawa-josui. We demonstrated that tree canopy openness was positively correlated with plant species richness, and the increased disturbance associated with developing historical sites as urban parks was negatively correlated with native plant species richness. In addition, there was significant species turnover in the plant community from upstream to downstream in Tamagawa-josui, which could largely be explained by spatial factors. We demonstrated that historical sites can provide potential habitats for the conservation of the plant species diversity, which is based on the effectiveness of the management of their vegetation.     

Fruit nutrient content and lipoxygenase activity in relation to the production of malformed and button berries in strawberry (Fragaria × ananassa Duch.)

Fruit nutrient content and lipoxygenase (LOX) activity were determined in strawberry fruit to establish a relationship, if it exists, between nutrients, and LOX activity with the fruit malformation and nubbins or button berry disorders. Nearly 17% fruit were affected by malformation and 10% by nubbins in open-field-grown strawberries. ‘Etna’ produced higher proportion of malformed (22.7%) as well as button berries (16.9%) and ‘Sweet Charlie’ the lowest (8.9% and 3.3%, respectively). Dry matter content (%) was lower in malformed (5.2%) and button berries (3.23%) than normal berries (7.41%). The concentration of P and Mg did not differ significantly, but that of N and K was notably higher and of Ca and B was lower in malformed and button berries than normal berries. Consequently, the N/Ca and K/Ca ratios were higher in malformed and button berries. LOX activity was significantly higher in malformed as well as button berries than normal berries, with significant differences among cultivars. The correlations between N, K and malformed and button berries were positive and between Ca and B, and malformed and button berries were negative. Similarly, the correlation between LOX activity and malformed, and button berries were also positive, indicating that excess of N and K, and deficiency of Ca and B are related to the production of malformed and buttons or nubbins in strawberry.     

Estimating urban green space production in the macroeconomy: From public goods to a profitable method of investment

Accompanied by long-term urbanization, the Chinese production of urban green space (UGS) is gradually transforming into a land operation strategy for local governments to maximize land lease revenue. This paper presents empirical research on different types of investment, urban space, and gross domestic product (GDP) with a simultaneous equations model (SEM) of econometrics to test the capital circulation and accumulation of UGS production in China. The regression results strongly support our hypothesis that UGS production contributes to GDP growth and that there is an economic feedback loop between them. One billion RMB of the government’s fixed-asset investments produces 0.899 km² UGS in the long term, and this UGS yields 1.749 billion RMB tertiary industry GDP in return. Thus, the total return rate in the representative economic chain of “fixed-asset investment-UGS-tertiary industry GDP” is greater than 174.9%. However, this percentage also reveals the weakness of providing rewards in maximizing land lease relative to urban industrial, traffic and residential spaces. We also estimate the lagged correlation coefficient with a rational distributed lag model, showing that the production of UGS has a longer-term and more profitable influence on tertiary industry GDP than on secondary industry GDP. The long-run effect of investment on UGS lasts for approximately five years in producing secondary industry GDP and more than ten years in producing tertiary industry GDP. A continuous increase in fixed-asset investments in UGS would achieve a balanced return rate (100%) and start to produce profits after the 4th year, according to the economic chain of ΔFAI-ΔUGS-ΔTGDP.     

Casual evaluation of the effects of a large-scale greenway intervention on physical and mental health: A natural experimental study in China

Many cross-sectional studies have supported the health benefits of urban greenways. However, the causal relationship between urban greenway intervention and residents’ physical and mental health remains unclear. Furthermore, the potential dose-response effect by distance to a greenway intervention remains unknown. This study explored the impact of a large-scale urban greenway intervention (construction of a 102-km-long East Lake Greenway in Wuhan, China) on the health outcomes of residents by using a natural experimental research design. We collected data before and after the intervention (in 2016 and 2019, respectively) from 1,020 participants living within a 5-km street-network distance from the entrances of this greenway. The average age of the participants was approximately 50, and most of them were married. More than half of the participants were female, currently employed, and had received a college education or above. Mixed-effects difference-in-difference (DID) models were used while controlling for individual and neighbourhood covariates. The results showed that the East Lake Greenway had a positive effect on the self-reported mental health of residents who lived within 2 km, and these benefits decreased with distance. The physical health benefit was insignificant. To increase the health benefits of urban greenways, more effort should be made to improve the accessibility of greenways and the surrounding environment. We also advocate that future natural experiments should explore the distance-varying dose-response effect of green space interventions on health outcomes.     

Similar spaces,different usage : A comparative study on how residents in the capitals of Finland and Denmark use cemeteries as recreational landscapes

Several studies from the Nordic countries show that cemeteries not only fulfil an important societal function as places for the disposal of bodily remains; they are also recreational landscapes that people visit to reflect, experience nature or perhaps go for a walk with the dog. In this comparative study, based on PPGIS data collected between 2018 and 2020 from residents in Copenhagen (Denmark) and Helsinki (Finland), we explored the extent to which residents use urban cemeteries as everyday recreational landscapes. We also assessed users’ characteristics and the values they attached to the cemeteries. The results show that several of Copenhagen’s cemeteries were actively used for recreation, while those in Helsinki were used much less frequently for this purpose. Of the total 7276 mapped visiting points in Copenhagen, 16.5% were located within cemeteries, compared with 1.9% of the 4298 mapped visiting points in Helsinki, hence conclusions from Helsinki should be drawn with caution. Physical activity and experiencing nature were the most common values attached to cemeteries in Copenhagen, whereas social interaction, spirituality and tranquillity were most common for Helsinki cemeteries. The results also revealed that younger Danes were particularly inclined to use cemeteries for social interactions, physical activity and spirituality and tranquillity. In the discussion, we elaborate on spatial differences between the cases, such as the availability of other green spaces, the size of cemeteries or people living in proximity to a cemetery, as well as on differences in policies and practices, including how Copenhagen stands out in actively promoting municipal cemeteries as recreational landscapes.     

Application method and rate of Trichoderma species as a biological control against Pythium aphanidermatum (Edson) Fitzp. in the production of microgreen table beets (Beta vulgaris L.)

Seed balls of ‘Early Wonder Tall Top’ table beet (Beta vulgaris L.) were incubated for 2 days at 21 °C in moist exfoliated grade 3 vermiculite (3 g seed balls [168 seed balls] and 1.1 g vermiculite) containing equal weights of Trichoderma harzianum Rifai strain KRL-AG2 G41 and T. virens strain G-41 (ThTv) at 0, 0.25, 0.50, 0.75 or 1.00 mg ThTv per seed ball. ThTv also was applied to the peat-lite growth medium 14 days before planting, at the same rates per seed ball as the seed ball treatments. Four days before planting, the peat-lite was inoculated with Pythium aphanidermatum (Edson) Fitzp. (Pa) at 0, 0.5 and 1.0× the rate that resulted in 96% damping-off when non-ThTv-treated dry seed balls were sown in peat-lite containing 1.0 Pa. Increasing ThTv level per seed ball decreased percentage damping-off, with 1.0 Pa giving greater percentage damping-off than 0.5 Pa. At 1 mg ThTv per seed ball, damping-off was 5% and 19% at 0.5 and 1.0 Pa, respectively. Including Agro-Lig UF (mostly humic acids) in the incubating seed-ball-ThTv mixture further decreased damping-off by an average 13 and 10 percentage points in 0.5 and 1.0 Pa, respectively. Increasing ThTv per seed ball in growth media decreased percentage damping-off, but not to the extent achieved with seed ball treatment, with 1 mg ThTv per seed ball giving 20% and 55% damping-off in 0.5 and 1.0 Pa, respectively. Decreasing incidence of damping-off with increasing ThTv application to seed balls or growth media was associated with increasing shoot fresh weight m⁻² at 14 days after planting, a response attributable to increased percentage plant survival and not to a ThTv growth-promoting effect.