Changes in nutrient allocation between roots and shoots of young maize plants during sulfate deprivation

Hydroponically grown maize (Zea mays L.) plants were deprived of the external source of sulfate following an initial period of 13 d during which the sulfur (S) supply was sufficient. The amounts of dry mass (DM), water, sulfate, sulfur, nitrate, ammonium, nitrogen, phosphorus, potassium, magnesium, calcium, boron, iron, copper, zinc, and manganese were monitored in the shoots and the roots for 10 d. The deprivation altered the nutritional balance between them, causing a 70% decrease of sulfate in shoots and roots after 2 d. At 10 d, 95% of sulfate had vanished in both shoots and roots. Total S remained rather constant in shoots or was slightly decreased in roots after 4 d. This coincided with a decrease of Fe in shoots after 4 d. The calculated decreases of S and Fe in –S shoots, up to 6 d were linearly correlated. Kinetic analysis of the changes revealed a sequence in their onset, and we distinguished early and late changes. Among the early changes, we highlight the following ones: (1) an increased amount of Cu in both shoots and roots at 2 d; Fe was 40% decreased in both shoots and roots at 2 d; (2) a decrease in transpiration rate by 35% after 2 d; (3) alterations in boron allocation; in –S shoots the % changes in S were linearly correlated with the corresponding % changes in B; (4) calcium content was not affected by the S deprivation in –S shoots, whilst it increased in –S root after d 2; (5) Mn and Mg decreased from the beginning and in a uniform fashion in both –S shoots and roots. Day 6 may be considered as the boundary between the early and late changes. The root fraction of DM increased progressively after 4 d. Changes in DM seemed to be similar to those of P. Changes of Zn also took place rather late. In –S shoots and for the time interval between 6 d and 10 d, linear correlations were found between the corresponding % changes of the pairs DM–S, DM–P, DM–N, DM–water, S–N, S–P, and N–P.     

A Power Function Based Approach for the Assessment of the Sulfate Deprivation Impact on Nutrient Allocation in Young Maize Plants

Thirteen-day-old maize (Zea mays L.) plants were exposed hydroponically to sulfur (S)-deprivation and their nutritional status was monitored for ten days. Sulfur (S) -deprivation altered the allocation of nutrients between roots and shoots in a differential manner and the effect was approached in terms of a power function. The experimental curvature was analyzed through the value of the exponent of the function and two formulations of the approach were tested through regression analysis. In the shoot, the impact of the S-deprivation relative to that on dry mass was: calcium (Ca) (45.3%) > nitrate (NO₃) (18.9%) > magnesium (Mg) (17.2%) > manganese (Mn) (14.1%) > water (W) = phosphorus (P) = potassium (K) = iron (Fe) = copper (Cu) > nitrogen (N) (?4.3%) > ammonium (NH₄₎ (?4.7%) > zinc (Zn) (?12%) > boron (B) (?21.4%) > S (?75.2%). In the root, the relative impact was: N = K = Ca = Zn = B > P (?12.7%) > NO₃ (?14.7%) > NH₄ (?18.4%) > W (?27.8%) > Mn (?34.4%) > Mg (?37.5%) > Fe = Cu (?40.5%) > S (?126.6%). Both models produced the same conclusions.     

An interview‐based approach assessing interactions between seals and small‐scale fisheries informs the conservation strategy of the endangered Mediterranean monk seal

1. Small‐scale fisheries may pose a serious threat to the conservation of marine mammals. At the same time various factors have led to the decline of small‐scale fisheries, often making them unsustainable. Current rates of biodiversity loss and the reduction of fish stocks and fisheries dictate a thorough understanding of fisheries‐related issues and the implementation of effective management actions.
2. The Mediterranean monk seal is one of the most endangered marine mammals on Earth; its survival in the eastern Mediterranean Sea is threatened by negative interactions with fisheries. A nationwide questionnaire survey among fishers and port police authorities was carried out in Greece to describe the main characteristics of small‐scale fisheries, and to understand the nature and assess the magnitude of negative interactions between the monk seal and these fisheries. Questionnaire information was verified by a second round of interviews during landings.
3. The main attributes of the fishers, their fishing boats, and their practices were characteristic of the small‐scale fisheries sector. Overfishing was considered the main reason for fish‐stock reduction, and negative interactions with marine mammals was considered the main issue for the fishing sector.
4. Monk seals were present, caused damage, and got accidentally entangled in fishing gear throughout Greece. Damage to fishing gear was recorded mainly during spring and summer, and on average affected 21% of all fishing trips and 1% of nets deployed during a fishing trip.
5. Based on these results, the implementation of general and specific nationwide fishery management and conservation actions are proposed. These actions are mainly aimed at improving fish stock status, changing the behaviour of the fishers, and mitigating seal–fishery interactions in Greece, while promoting the recovery of the Mediterranean monk seal in the eastern Mediterranean Sea.

     

Modeling the Trends of Nutrient Concentration Dynamics in S-Deprived Young Maize Plants

Sulfate deprivation altered nutrient concentrations in both shoot and root of young maize (Zea mays L.) plants. A model is presented to that simulates the trends of nutrient concentration dynamics relative to the dry mass accumulation in the roots and shoots of plants grown in sulfate-deprived nutrient solution against control. The relationship was found to adequately follow an allometric pattern, the exponent of which could be used to describe the trend of the course, whilst the differential fluctuation types for each nutrient were highlighted. Sulfate-deprivation altered the inclination of the trendline in a differential way for each nutrient, and in several cases reversed the fluctuation pattern. The exponents were ranked in decreasing order, ranking in this way the trends of the concentration dynamics for each nutrient. Observed low R²-values reflected significant scatter of the data set around the trendline.     

Spatial limitations in forest biomass harvesting using Geographic Information System and Remote Sensing for an ecological and sustainable bioenergy framework

As the sustainable forest biomass harvesting process is highly influenced by the terrain, the heterogeneity, and the protection status of the landscape, this study highlights the GIS and Remote Sensing as important scientific tools, assisting in the planning process and integrating the appropriate spatial limitations for an ecological forest biomass extraction in a rational bioenergy utilization framework. This study is focused on the northwest Greece and particularly in the regional unit of Grevena which is part of the Western Macedonia region, the region with the highest unemployment rates in Greece. As the forests in the regional unit of Grevena occupy a significant percentage over half of the regional unit area, the emphasis on the sustainable harvesting and utilization of forest biomass for energy purposes could tackle unemployment rates, enhance the energy autonomy of the remote mountain villages, and reduce the Mediterranean forest fire risk. The spatial data process and the implied spatial limitations unfold a methodology procedure, which is revealing specifically quantified and illustrated results as are emerging progressively the oak forests of the regional unit of Grevena with biomass harvesting capabilities, which do not belong to the Grevena’s protected areas, have accessible slopes and lower diversity index.