Seed provenance determines germination responses of Rumex crispus (L.) under water stress and nutrient availability

2019 ◽  
Vol 12 (6) ◽  
pp. 949-961 ◽  
Author(s):  
María Pérez-Fernández ◽  
Carole P Elliott ◽  
Alex Valentine ◽  
José Antonio Oyola

Abstract Aims Seeds of Rumex crispus from six provenances were studied in relation to their germination under drought and presence of nitrogen in the germination and emergence media. We also investigated whether adaptation to soil increases the ability of the species to colonize and establish in contrasting environments along a longitudinal gradient in western Spain by means of a reciprocal transplantation experiment. Methods We conducted a germination trial in the lab to test for the germination responses to water scarcity along a polyethylene glycol gradient and to varying concentrations of nitrogen compounds. Simultaneously reciprocal transplantations experiment was conducted, where seeds from six provenances were grown in the soils from the very same provenances. Seedling emergence, survivorship and fitness-related variables were measured in all plots. Important Findings We found that R. crispus has a cold-stratification requirement that enhances its germination. Significant differences between the six provenances were detected for time-to-germination, total seedling emergence, plant mortality and reproductive effort in all the experiments. The differences between provenances with respect to germination were confirmed by the significant statistical analyses of the variance, thus providing evidence that seeds from parent plants grown in different environmental conditions have an intrinsically different abilities to germinate and establish. Soil nitrogen content where seed germination and seedlings establish also play an important role in their performance in terms of survivorship and reproduction, being the higher levels of inorganic nitrogen and of microbial biomass those that increased biomass production, enhanced inflorescence formation and reduced plant mortality. We conclude that one of the main reasons for the spread and maintenance of R. crispus would be the increased levels of nitrogen in agricultural soils.

Agronomy ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 444 ◽  
Author(s):  
Chen-Chi Tsai ◽  
Yu-Fang Chang

Adding biochar to excessive compost amendments may affect compost mineralization rate and nitrogen (N) availability. The objective of this 371-day incubation study was to evaluate the effects of four proportions of woody biochar (0%, 0.5%, 1.0%, and 2.0%) from lead tree (Leucaena leucocephala (Lam.) de. Wit) biochar produced at 750 °C through dynamic mineral N and N mineralization rates in three rural soils (one Oxisol and two Inceptisols). In each treatment, 5% poultry–livestock manure compost was added to serve as an excessive application. The results indicated that the biochar decreased available total inorganic nitrogen (TIN) (NO3−-N+NH4+-N) by on average 6%, 9% and 19% for 0.5%, 1.0% and 2.0% treatments, respectively. The soil type strongly influenced the impact of the biochar addition on the soil nitrogen mineralization potential, especially the soil pH and clay content. This study showed that the co-application of biochar and excessive compost benefited the agricultural soils by improving NO3−-N retention in agroecosystems. The application of biochar to these soils to combine it with excessive compost appeared to be an effective method of utilizing these soil amendments, as it diminished the net N mineralization potential and reduced the nitrate loss of the excessive added compost.


Ecosystems ◽  
2021 ◽  
Author(s):  
Elisa Soana ◽  
Fabio Vincenzi ◽  
Nicolò Colombani ◽  
Micòl Mastrocicco ◽  
Elisa Anna Fano ◽  
...  

AbstractDenitrification is a key process buffering the environmental impacts of agricultural nitrate loads but, at present, remains the least understood and poorly quantified sink in nitrogen budgets at the watershed scale. The present work deals with a comprehensive and detailed analysis of nitrogen sources and sinks in the Burana–Volano–Navigabile basin, the southernmost portion of the Po River valley (Northern Italy), an intensively cultivated (> 85% of basin surface) low-lying landscape. Agricultural census data, extensive monitoring of surface–groundwater interactions, and laboratory experiments targeting N fluxes and pools were combined to provide reliable estimates of soil denitrification at the basin scale. In the agricultural soils of the basin, nitrogen inputs exceeded outputs by nearly 40% (~ 80 kg N ha−1 year−1), but this condition of potential N excess did not translate into widespread nitrate pollution. The general scarcity of inorganic nitrogen species in groundwater and soils indicated limited leakage and storage. Multiple pieces of evidence supported that soil denitrification was the process that needed to be introduced in the budget to explain the fate of the missing nitrogen. Denitrification was likely boosted in the soils of the studied basin, prone to waterlogged conditions and consequently oxygen-limited, owing to peculiar features such as fine texture, low hydraulic conductivity, and shallow water table. The present study highlighted the substantial contribution of soil denitrification to balancing nitrogen inputs and outputs in agricultural lowland basins, a paramount ecosystem function preventing eutrophication phenomena.


Plant Disease ◽  
2018 ◽  
Vol 102 (7) ◽  
pp. 1434-1444
Author(s):  
Yukari Shimizu ◽  
Daiki Sagiya ◽  
Mariko Matsui ◽  
Ryo Fukui

Effects of monosaccharide-amended soils on suppression of Rhizoctonia damping-off of sugar beet were compared under controlled experiments. Suppressive effects of glucose, fructose, sorbose, and xylose were significantly (P < 0.001) greater than that of galactose or mannose but the effect of sorbose was reduced by soil treatments with antibiotics. Saprotrophic growth of Rhizoctonia solani in the laimosphere also was suppressed by glucose, fructose, sorbose, and xylose, whereas only sorbose repressed pericarp colonization. Sugar alcohols (mannitol, sorbitol, and xylitol) neither suppressed Rhizoctonia damping-off nor halted the saprotrophic growth of the pathogen. Seed germination was not affected by any of these six monosaccharides, whereas galactose and mannose inhibited seedling emergence significantly (P < 0.001) compared with the nontreated control or other monosaccharides. Soil fertilization with inorganic nitrogen at a C/N ratio of 20:1 negated the suppressive effects of glucose and fructose on both damping-off and saprotrophic colonization but improved seedling growth in carbonized soils. Obviously, microbial competition for mineral nitrogen was responsible for disease suppression; however, it delayed seedling growth after emergence. This paradox was resolved by adding glucose to the top 1-cm surface-soil zone at a C/N ratio of 50:1 or 125:1. This protected the laimosphere, resulting in effective disease suppression while complementarily enhancing seedling growth.


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