Wheat Grain Protein Content under Mediterranean Conditions Measured with Chlorophyll Meter.

Adequate N fertilisation is crucial to increase the grain protein content (GPC) values in wheat. The recommended level of GPC needed to achieve high-quality bread-making flour should be higher than 12.5%. However, it is difficult to ensure the GPC values that the crop will achieve because N in grain is derived from two different sources: N remobilized into the grain from N accumulated in the pre-anthesis period, and N absorbed from the soil in the post-anthesis period. This study aimed to (i) evaluate the effect of the application of N on the rate of stem elongation (GS30) when farmyard manures are applied as initial fertilisers on GPC and on the chlorophyll meter (CM) values at mid-anthesis (GS65), (ii) establish a relationship between the CM values at GS65 and GPC, and (iii) determine a minimum CM value at GS65 to obtain GPC values above 12.5%. Three field trials were performed in three consecutive growing seasons, and different N fertilisation doses were applied. Readings using the CM Yara N-TesterTM were taken at GS65. The type of initial fertiliser did not affect the GPC and CM values. Generally, the greater the N application at GS30 is, the higher the GPC and CM values are. CM values can help to estimate GPC values only when yields are below 8000 kg ha-1. Additionally, CM values at GS65 should be higher than 700 to achieve high-quality bread-making flour (12.5%) at such yield levels. These results will allow farmers and cooperatives to make better decisions regarding late-nitrogen fertilisation and wheat sales.

15N Natural Abundance Evidences a Better Use of N Sources by Late Nitrogen Application in Bread Wheat.

This work explores whether the natural abundance of N isotopes technique could be used to understand the movement of N within the plant during vegetative and grain filling phases in wheat crop (Triticum aestivum L.) under different fertilizer management strategies. We focus on the effect of splitting the same N dose through a third late amendment at flag leaf stage (GS37) under humid Mediterranean conditions, where high spring precipitations can guarantee the incorporation of the lately applied N to the soil-plant system in an efficient way. The results are discussed in the context of agronomic parameters as N content, grain yield and quality, and show that further splitting the same N dose improves the wheat quality and induces a better nitrogen use efficiency. The nitrogen isotopic natural abundance technique shows that N remobilization is a discriminating process that leads to an impoverishment in 15N of senescent leaves and grain itself. This technique also reflects the more efficient use of N resources (fertilizer and native soil-N) when plants receive a late N amendment.

Grape yield and quality responses to simulated year 2100 expected climatic conditions under different soil textures.

BACKGROUND: The influence of global warming on grape quality is a great concern among grapegrowers and enologists. The effects of simulated year 2100 expected CO2 , temperature and relative humidity (RH) conditions (FCC; 700 µmol CO2 mol-1 air, 28/18 °C day/night and 33/53% RH, day/night) versus the current situation (Curr; 390 µmol CO2 mol-1 air, 24/14 °C and 45/65% RH); well-irrigated versus expected future water deficit and three soils with different clay contents (41, 19 and 8%) on yield and berry quality of grapevine cv. Tempranillo were evaluated. RESULTS: FCC shortened the time between fruit set and veraison and between fruit set and maturity by up to 7 and 10 days, respectively. This faster maturity led to higher must pH and tonality and reduced malic and tartaric acid concentrations, total anthocyanin concentration and colour intensity. Water deficit delayed ripeness for up to 9 days and reduced vegetative growth and malic acid concentration of grapes. However, this malic acid reduction did not occur with the clayey soils. These soils induced the lowest root fresh weight and berries with lower total anthocyanin concentration. CONCLUSION: Among the adaptation techniques to cope with the described effects on fruit composition, soil selection should be considered with attention in addition to irrigation practices. © 2016 Society of Chemical Industry.

How will climate change influence grapevine cv. Tempranillo photosynthesis under different soil textures?

While photosynthetic responses to elevated CO2, elevated temperature, or water availability have previously been reported for grapevine as responses to single stress factors, reports on the combined effect of multiple stress factors are scarce. In the present work, we evaluated effects of simulated climate change [CC; 700 ppm CO2, 28/18 °C, and 33/53% relative humidity (RH), day/night] versus current conditions (375 ppm CO2, 24/14 °C, and 45/65% RH), water availability (well-irrigated vs. water deficit), and different types of soil textures (41, 19, and 8% of soil clay contents) on grapevine (Vitis vinifera L. cv. Tempranillo) photosynthesis. Plants were grown using the fruit-bearing cutting model. CC increased the photosynthetic activity of grapevine plants grown under well-watered conditions, but such beneficial effects of elevated CO2, elevated temperature, and low RH were abolished by water deficit. Under water-deficit conditions, plants subjected to CC conditions had similar photosynthetic rates as those grown under current conditions, despite their higher sub-stomatal CO2 concentrations. As expected, water deficit reduced photosynthetic activity in association with inducing stomatal closure that prevents water loss. Evidence for photosynthetic downregulation under elevated CO2 was observed, with decreases in photosynthetic capacity and leaf N content and increases in the C/N ratio in plants subjected to CC conditions. Soil texture had no marked effects on photosynthesis and did not modify the photosynthetic response to CC and water-deficit conditions. However, in mature well-irrigated plants grown in the soils with the highest sand content, an important decrease in stomatal conductance was observed as well as a slight decrease in the utilization of absorbed light in photosynthetic electron transport (measured as photochemical quenching), possibly related to a low water-retention capacity of these soils even under well-watered conditions.

Molecular microbial biodiversity assessment: a biological indicator of soil health.

The soil performs a variety of key functions: (i) provides the food, fuel, and fiber needs of the world's population, (ii) regulates the quality of the air and water, (iii) decomposes organic wastes, (iv) recycles nutrients, and (v) acts as a sink for pollutants (including global gases). Soil degradation is increasingly recognized as an urgent environmental issue and a crucial need exists for the capacity to evaluate soil health. After all, soil health is a key component in sustaining the different world's ecosystems and the myriad of natural and socioeconomic systems they support. In this respect, soil health has been defined as the "continued capacity of a specific kind of soil to function as a vital living system, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, to maintain or enhance the quality of air and water environments, and to support human health and habitation". A biological indicator is an organism, a part of an organism, or a community of organisms, used to obtain information about environmental quality. The assessment of microbial biodiversity has the potential to provide useful insight into the health and functioning of soil. Our inability to culture most microorganisms that are present in soils has, until recently, impaired studying the relationships between the structure and the function of soil microbial communities. This shortcoming has been recently overcome by using several molecular techniques that allow the detection, enumeration, and characterization of soil microorganisms without cultivation.

Soil enzyme activities as biological indicators of soil health.

Soil health can be defined as the continued capacity of a specific kind of soil to function as a vital living system, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, to maintain or enhance the quality of air and water environments, and to support human health and habitation. Because of the conflicting pressures increasingly applied to the soil, it is clear that relevant indicators are urgently needed to assess and monitor soil health. Biological indicators of soil health offer certain advantages over physicochemical methods. Among the various biological indicators that have been proposed to monitor soil health, soil enzyme activities have great potential to provide a unique integrative biological assessment of soils and the possibility of assessing the health of the soil biota. Besides, soil enzyme activities provide an easy, relatively rapid, and low cost procedure to monitor soil health. Nevertheless, soil enzyme activities also present some limitations and must always be considered in conjunction with other biological and physicochemicals measurements if we are to diagnose soil health correctly.