Low Soil Nitrogen Research Articles

English

Maize (Zea mays L.) is the most important cereal crop on which many smallholder farmers in sub-Sahara Africa (SSA) depend on as a sole source of calories, proteins, and vitamins. However, conventional maize is deficient in two essential amino acids, lysine, and tryptophan. Thereafter, Quality Protein Maize (QPM) developed to combat protein malnutrition. In SSA low soil nitrogen is also the most limiting factor in maize production and productivity. To determine the combining ability of QPM inbred lines for grain yield and other agronomic traits under low and optimum N environments, 121 genotypes generated using 11 QPM inbred lines in a complete diallel mating design with 5 checks were evaluated under both low and optimum N environments at 3 locations in the 2018 cropping season. Significant differences were observed among the genotypes for major characters under both low and optimum N environments. Under low and optimum N environments, non-additive gene actions were more important than additive gene action for grain yield, number of ears per plant, plant and ear height, ear length and diameter. Under low N environments, more contributions of reciprocal effects than GCA effects were observed for number of ears per plant, plant aspect, ear diameter. Parental lines TL156579, TL156583, and TL148288 were considered as a good general combiner for grain yield under low N environments. Parental line TL156612 showed higher positive GCA effects when used as female while parental line TL156612 showed higher negative GCA effects when used as a male parent for grain yield under low N environments.   Key words: Complete diallel, general combining ability, low soil nitrogen, lysine, optimum soil nitrogen, quality Protein maize, reciprocal effect, tryptophan.

Divergent responses of plant biomass and its allocation to the altered precipitation regimes among different degraded grasslands in China

Climate models predict shifts in precipitation patterns characterized by increased precipitation amount and decreased frequency for semi-arid grasslands in northeast China. However, under these novel climatic conditions, potential differences in plant biomass and its allocation among different degraded grasslands remain unclear. We conducted a mesocosm experiment to test the effects of higher precipitation amount (increased by 50% from the long-term mean) and lower frequency (decreased by 50%) on plant biomass and allocation in the lightly, moderately, and severely degraded grasslands. Lower precipitation frequency promoted belowground biomass but reduced aboveground biomass through enhancing soil water variability. Higher precipitation amount enhanced aboveground biomass in the lightly and moderately degraded grasslands, but not in the severely degraded grassland due to lower soil nitrogen availability. Lower precipitation frequency weakened or ended the positive effects of higher precipitation amount on aboveground and belowground biomass, and higher precipitation amount suppressed the enhancement of lower precipitation frequency on belowground biomass, which could be attributed to temporary waterlogging. Plants in the moderately degraded grassland preferred to adjust root vertical distribution, which was impacted by the changes in plant community composition. However, adjustment of aboveground biomass vs. belowground biomass was the primary biomass allocation strategy in the other two grasslands. Our findings emphasized the importance of considering the degradation level of grasslands when predicting responses of ecosystem functions to the projected changes in precipitation regimes. These findings are critical for making feasible decisions for the sustainable management of degraded grasslands. Legend: + and − indicate positive and negative relationships, respectively LDG, MDG and SDG-lightly degraded, moderately degraded and severely degraded grasslands, respectively DPF-decreased precipitation frequency treatment, IPA-increased precipitation amount treatment SWC and CVSWC-mean and variation of soil water content, respectively SINC-soil inorganic nitrogen content AGB and BGB-aboveground and belowground biomass, respectively fAGB-AGB / total biomass BGB0–10 (%)-belowground biomass proportion in the 0–10 cm soil layer, $${{{\text{BGB}}_{{0 - 10}} } \mathord{\left/ {\vphantom {{{\text{BGB}}_{{0 - 10}} } {{\text{BGB}}_{{0 - 30}} {\text{~}} \times 100}}} \right. \kern-\nulldelimiterspace} {{\text{BGB}}_{{0 - 30}} \times 100}}$$ RAGB-relative aboveground biomass

Comparative Response of Some Tropical Maize Hybrid and Their Parental Varieties to Low and High Nitrogen Regime

The study was carried to investigate the differential response of some maize hybrids and their open pollinated parents to low and high nitrogen soil condition. Hybrids recorded shorter plant height under the two different nitrogen fertilizer conditions compare with open pollinated parents. Thus the hybrids are better for mechanical harvesting. Taller ear height was observed among the hybrids compare with the open pollinated parents; rate of stem and root lodging were consequently higher among the hybrids. Hybrid had better husk cover under both nitrogen fertilizer regime; that’s they will be less susceptible to insect and animal attack. Mean difference of ear per plant between the maize hybrids and open pollinated parents was not significant. Significant difference was observed between maize hybrids and their parents for grain yield under low and high fertilizer regimes. That the hybrids had higher grain yield under both nitrogen fertilizer regime; indicates the tolerance of maize hybrid to low-N condition than the parental varieties. Low-N environment seemed to favor shorter day to silk for maize hybrid, however, high nitrogen soil condition appeared to increase day to silk. It is an evidence that flowering and consequently maturity time is delayed under favorable nitrogen soil environments. Days to 50% pollen shed are significantly different among the maize hybrids and their parents. The maize hybrids attained day to pollen earlier than the parents under both fertilizer regime. It is an indication that setting of maize grain occur earlier among hybrids than their open pollinated parents

Nitrogen Fertilization and Native C4 Grass Species Alter Abundance, Activity, and Diversity of Soil Diazotrophic Communities.

Native C4 grasses have become the preferred species for native perennial pastures and bioenergy production due to their high productivity under low soil nitrogen (N) status. One reason for their low N requirement is that C4 grasses may benefit from soil diazotrophs and promote biological N fixation. Our objective was to evaluate the impact of N fertilization rates (0, 67, and 202 kg N ha–1) and grass species (switchgrass [Panicum virgatum] and big bluestem [Andropogon gerardii]) on the abundance, activity, diversity, and community composition of soil diazotrophs over three agricultural seasons (grass green-up, initial harvest, and second harvest) in a field experiment in East Tennessee, United States. Nitrogen fertilization rate had a stronger influence on diazotroph population size and activity (determined by nifH gene and transcript abundances) and community composition (determined by nifH gene amplicon sequencing) than agricultural season or grass species. Excessive fertilization (202 kg N ha–1) resulted in fewer nifH transcripts compared to moderate fertilization (67 kg N ha–1) and decreased both richness and evenness of diazotrophic community, reflecting an inhibitory effect of high N application rates on soil diazotrophic community. Overall, cluster I and cluster III diazotrophs were dominant in this native C4 grass system. Diazotroph population size and activity were directly related to soil water content (SWC) based on structural equation modeling. Soil pH, SWC, and C and N availability were related to the variability of diazotrophic community composition. Our results revealed relationships between soil diazotrophic community and associated soil properties, adding to our understanding of the response of soil diazotrophs to N fertilization and grass species in native C4 grass systems.

Gene Action, Heterotic Patterns, and Inter-Trait Relationships of Early Maturing Pro-Vitamin A Maize Inbred Lines and Performance of Testcrosses under Contrasting Environments

Vitamin A deficiency is the leading cause of night blindness, total blindness, maternal and childhood mortality in developing countries. Drought, low soil nitrogen and Striga hermonthica parasitism are major constraints to maize production in sub-Saharan Africa (SSA). Thus, the development of multiple stress tolerant maize varieties with elevated levels of PVA is an economically feasible approach to simultaneously tackle malnutrition and food insecurity in SSA. The objectives of this study were to determine the gene action modulating the inheritance of grain yield and other traits, group the inbred lines, investigate inter-trait relationships among grain yield and other traits and assess the performance and stability of single-cross hybrids derived from a set of inbred lines under stress and non-stress environments. One hundred and ninety diallel crosses plus six hybrid checks were evaluated under managed drought at Ikenne during the 2016/17 and 2017/18 dry seasons, low soil N conditions at Mokwa and Ile-Ife, Striga infestation at Abuja and Mokwa, and optimal management conditions at Ikenne, Kadawa, Abuja, Bagauda and Mokwa during the 2016 and 2017 growing seasons. Both additive and non-additive gene actions were prominent in the inheritance of grain yield and other measured traits under stress and optimal management conditions. However, additive gene action was preponderant over the non-additive. The PVA inbreds were classified into three heterotic groups with TZEI 25 and TZEIOR 164 identified as inbred testers for heterotic groups 2 and 3, respectively. Plant and ear heights, ears per plant, plant and ear aspects were identified as reliable secondary traits for genetic enhancement of grain yield under both stress and non-stress conditions. Hybrids TZEIOR 4 × TZEIOR 158 and TZEIOR 119 × TZEIOR 158 were outstanding in performance and should be tested extensively for possible commercialization to combat malnutrition and food insecurity in SSA.

Strategies for Selecting Early Maturing Maize Inbred Lines for Hybrid Production under Low Soil Nitrogen and Striga Infestation

Development, testing and selection of superior inbred lines is crucial for the success of a hybrid program targeting Striga-infested and low soil nitrogen (low-N) environments. The practical value of inbred lines is determined by multiple traits, most of which are inter-dependent. The main objective of this study was to identify early maturing inbred lines based on multiple traits under optimal, low-N and Striga-infested environments for hybrid development and population improvement. One hundred early maturing inbred lines were evaluated under artificial Striga-infestation, low-N and optimal growing environments for two years at Kwadaso and Nyankpala in Ghana. The inbred lines exhibited high levels of genetic variability for grain yield and other agronomic traits desirable for Striga resistance and low-N tolerance. Under optimal growing conditions, days to silking (DS), ears per plot (EHARV) and days to anthesis (DA) had high direct effects on grain yield (GYLD). Days to silking and ears per plant (EPP) had the highest positive direct effects on GYLD, while DA had the highest negative direct effect on grain yield in low-N environments. Under Striga-infestation, the highest negative direct effect on GYLD was obtained with EASP. All the measured traits previously identified to have direct influence on grain yield were associated with it and could be used for indirect selection for improved grain yield under the contrasting environments. Forty-eight of the 100 inbred lines studied were identified as low-N tolerant and forty-nine as Striga resistant.

Genetic diversity and inter-trait relationship of tropical extra-early maturing quality protein maize inbred lines under low soil nitrogen stress.

Information on the genetic diversity, population structure, and trait associations of germplasm resources is crucial for predicting hybrid performance. The objective of this study was to dissect the genetic diversity and population structure of extra-early yellow and orange quality protein maize (QPM) inbred lines and identify secondary traits for indirect selection for enhanced grain yield under low-soil nitrogen (LN). One hundred and ten inbred lines were assessed under LN (30 kg ha -1) and assayed for tryptophan content. The lines were genotyped using 2500 single nucleotide polymorphism (SNP) markers. Majority (85.4%) of the inbred lines exhibited wide pairwise genetic distances between 0.4801 and 0.600. Genetic distances were wider between yellow and orange endosperm lines and predicted high heterosis in crosses between parents of different endosperm colors. The unweighted pair group method with arithmetic mean (UPGMA) and the admixture model-based population structure method both grouped the lines into five clusters. The clustering was based on endosperm color, pedigree, and selection history but not on LN tolerance or tryptophan content. Genotype by trait biplot analysis revealed association of grain yield with plant height and ear height. TZEEQI 394 and TZEEIORQ 73A had high expressivity for these traits. Indirect selection for high grain yield among the inbred lines could be achieved using plant and ear heights as selection criteria. The wide genetic variability observed in this study suggested that the inbred lines could be important sources of beneficial alleles for LN breeding programs in SSA.

Sources of tolerance to low soil nitrogen in some Striga resistant and quality protein maize (Zea mays L.) varieties

Sources of tolerance to low soil nitrogen in some Striga resistant and quality protein maize (Zea mays L.) varieties

Soil greenhouse gas emissions from a sisal chronosequence in Kenya

Sisal (Agave sisalana) is a climate-resilient crop grown on large-scale farms in semi-arid areas. However, no studies have investigated soil greenhouse gas (GHGs: CO2, N2O and CH4) fluxes from these plantations and how they relate to other land cover types. We examined GHG fluxes (Fs) in a sisal chronosequence at Teita Sisal Estate in southern Kenya. The effects of stand age on Fs were examined using static GHG chambers and gas chromatography for a period of one year in seven stands: young stands aged 1–3 years, mature stands aged 7–8 years, and old stands aged 13–14 years. Adjacent bushland served as a control site representing the surrounding land use type. Mean CO₂ fluxes were highest in the oldest stand (56 ± 3 mg C m-2 h-1) and lowest in the 8-year old stand (38 ± 3 mg C m-2 h-1), which we attribute to difference in root respiration between the stand. All stands had 13–28% higher CO₂ fluxes than bushland (32 ± 3 mg C m-2 h-1). CO2 fluxes in the wet season were about 70% higher than dry season across all sites. They were influenced by soil water content (WS) and vegetation phenology. Mean N2O fluxes were very low (<5 µg N m-2 h-1) in all sites due to low soil nitrogen (N) content. About 89% of CH4 fluxes were below the detection limit (LOD ± 0.02 mg C m-2 h-1). Our results imply that sisal plantations have higher soil CO2 emissions than the surrounding land use type, and the seasonal emissions were largely driven by WS and the vegetation status. Methane and nitrous oxide are of minor importance. Thus, soil GHG fluxes from sisal plantations are a minor contributor to agricultural GHG emissions in Kenya.

High Seeding Rates and Low Soil Nitrogen Environments Optimize Weed Suppression and Profitability in Organic No-Till Planted Soybean

No-till planting crops into rolled-crimped cover crops can improve soil health while reducing labor and fuel requirements compared with traditional tillage-based production. However, little information is available to help farmers optimize the management of organic no-till planted crops. Weed suppression, crop yield, and profitability were assessed across soybean [Glycine max (L.) Merr.] seeding rates and soil nitrogen environments in an experiment conducted at two sites in central New York. Soybeans were no-till planted into rolled-crimped cereal rye (Secale cereale L.) at 0, 185,000, 371,000, 556,000, and 741,000 seeds ha−1. Three rates (0, 63, or 125 kg ha−1) of sodium nitrate (15-0-2) were applied across seeding rates to create different soil nitrogen environments. When pooled over sites, the lowest weed biomass occurred at the highest soybean density in the lowest soil nitrogen environment. An interaction was observed between soybean seeding rate and nitrogen treatments on weed communities. Soybean yield increased asymptotically with crop density and was not affected by nitrogen or site treatments. When pooled over nitrogen treatments and sites, partial returns to the soybean seeding rates were maximized at $2,238 ha−1 with 527,800 seeds ha−1. Results suggest that crop density is an important lever for optimizing weed suppression and crop yield in organic no-till soybean, and that managing for low soil nitrogen conditions may further enhance weed suppression while maintaining high yields.

Biostimulant Activity of Azotobacter chroococcum and Trichoderma harzianum in Durum Wheat under Water and Nitrogen Deficiency

Biostimulants hold great potential for developing integrated sustainable agriculture systems. The rhizobacteria Azotobacter chroococcum strain 76A and the fungus Trichoderma harzianum strain T22, with demonstrated biostimulant activity in previous systems, were evaluated in Triticum durum cv Creso for their ability to enhance growth and tolerance to drought stress. Growth and drought tolerance were evaluated in conditions of low and high soil nitrogen, with two levels of water stress. T. harzianum increased plant growth (+16%) under control conditions and tolerance to moderate drought stress (+52%) under optimal fertilization, while A. chroococcum conferred a growth penalty (−28%) in well-watered conditions under suboptimal fertilization and increased tolerance only under extreme drought stress (+15%). This growth penalty was ameliorated by nitrogen fertilization. T. harzianum abundance was found to be positively correlated to extreme soil drying, whereas A. chroococcum-induced tolerance was dependent on soil nitrogen availability. These results indicate that while biostimulants may enhance growth and stress tolerance, nutrient availability soil and environmental conditions heavily influence these responses. These interactions should be considered when designing biostimulant products targeted to specific cultural conditions.

Coal Fly Ash and Polyacrylamide Influence Transport and Redistribution of Soil Nitrogen in a Sandy Sloping Land

Sandy soils are prone to nutrient losses, and consequently do not have as much as agricultural productivity as other soils. In this study, coal fly ash (CFA) and anionic polyacrylamide (PAM) granules were used as a sandy soil amendment. The two additives were incorporated to the sandy soil layer (depth of 0.2 m, slope gradient of 10°) at three CFA dosages and two PAM dosages. Urea was applied uniformly onto the low-nitrogen (N) soil surface prior to the simulated rainfall experiment (rainfall intensity of 1.5 mm/min). The results showed that compared with no addition of CFA and PAM, the addition of CFA and/or PAM caused some increases in the cumulative NO3−-N and NH4+-N losses with surface runoff; when the rainfall event ended, 15% CFA alone treatment and 0.01–0.02% PAM alone treatment resulted in small but significant increases in the cumulative runoff-associated NO3−-N concentration (p &lt; 0.05), meanwhile 10% CFA + 0.01% PAM treatment and 15% CFA alone treatment resulted in nonsignificant small increases in the cumulative runoff-associated NH4+-N concentration (p &gt; 0.05). After the rainfall event, both CFA and PAM alone treatments increased the concentrations of NO3−-N and NH4+-N retained in the sandy soil layer compared with the unamended soil. As the CFA and PAM co-application rates increased, the additive effect of CFA and PAM on improving the nutrient retention of sandy soil increased.

Review on Genetic and Breeding for Low -N tolerance in Maize

Low soil nitrogen (Low N) is one of the major abiotic stresses causing maize yield reduction in tropics of Africa. However, genetic variation observed under low N and crossing among adaptive/NUE elite lines should be targeted for different secondary traits, economic disease and inheritance studies breeding for Low N in maize. In addition, breeding for Low N and drought have common traits indicating that common adaptive mechanism and thus, appear to develop maize genotypes that tolerance to stress and such maize genotypes exhibited high yield performance under low and high N condition across environments, is likely good for subsistence farmers in Africa for maize production. Multiple QTLs detected under Low N and high-nitrogen conditions for grain yield per plant, secondary and physiological traits. However, a direct use of these detected QTLs has been less achieved breeding for Low N tolerance in maize program, because of eQTLs. Thus, stable QTLs should be validated and fine mapping or GWAS method should detect the candidate genes for controlling NUE for low soil nitrogen in maize. Keyword : Low N, secondary traits, genotypes, NUE, QTLs DOI: 10.7176/JNSR/12-1-04 Publication date: January 31 st 2021

Heterotic grouping of tropical maize inbred lines and their hybrid performance under stem borer infestation and low soil nitrogen condition in West and Central Africa

Low soil nitrogen (low-N) and stem borer attack are two of the major stresses limiting maize production in West and Central Africa (WCA). Thus, there is need to intensify efforts aimed at identifying inbred lines with resistance and tolerance to these stresses for hybrid development. The objectives of the study were to determine the combining ability of maize inbred lines, classify them into heterotic groups using both conventional and marker-based approaches, compare the efficiency of the different grouping methods and evaluate the performance of the hybrids generated from the inbred lines under contrasting environments. Ten white maize inbred lines with varying levels of resistance to stem borers were selected and crossed in a diallel in 2015. The resulting 45 hybrids were evaluated together with five checks in 10 environments under low-N, artificial stem borer infestation and non-stress conditions in Nigeria. General combining ability (GCA) and specific combining ability (SCA) were highly significant (p ≤ 0.01) for most of the traits studied but GCA was predominant over SCA under each and across research conditions. Inbred line 2 combined significant positive GCA for grain yield with significant negative GCA for traits of resistance to stem borers and tolerance to low-N. Each of the grouping methods classified the inbred lines into 3 heterotic groups but SCA and heterotic groups’ specific and general combining ability had the joint highest breeding efficiency. Hybrids 1 × 4, 2 × 3, 1 × 6 and 2 × 5 were identified to be high yielding and stable across environments and can serve as candidates for further on-farm evaluations and eventual release in WCA.

N immobilization treatment revisited: A retarded and temporary effect unfolded in old‐field restoration

AbstractAimThere is increasing recognition that plant–soil feedbacks drive species co‐existence; therefore the below‐ground compartment should be better considered in ecological restoration. Addition of carbon is a restoration measure that relies on indirect plant–soil relationships by immobilizing soil nitrogen in microbial biomass to manipulate competitive hierarchies between plant species. The aim of the present work was to evaluate the impact of six years of carbon amendment in old‐field restoration in the long term, 20 years after the first application.LocationOld‐fields and reference sand steppe on dry calcareous sandy soil in Fülöpháza, Kiskun LTER site (46°53′ N, 19°24′ E), Hungary, Pannonian biogeographic region, Europe.MethodsWe applied carbon amendment in the form of sucrose and sawdust on three abandoned agricultural fields between 1998 and 2003. Vegetation was surveyed in 1998–2006 and re‐sampled in 2008, 2010 and 2018 on permanent 2 m × 2 m coenological relevés for carbon‐amended, control and reference plots (n = 144). We used principal response curves (PRC) to describe vegetation development trajectories and linear mixed‐effects models to test changes in cover of vascular plants and cryptogams, nitrogen requirement groups and restoration species groups with time and treatment.ResultsCarbon amendment resulted in lower soil nitrogen availability, and lower cover of vascular plants and cryptogams compared to control, but these differences became visible only four to five years after the first application and disappeared three years after the cessation of treatment. Minor treatment effects on the cover of oligotrophic, mesotrophic and target species were found.ConclusionsCarbon amendment did not speed up the recovery of sand grasslands; however, the reduction of cover (vegetation and cryptogam) can be a window of opportunity for other species to colonize that can be used as a complement to other treatments. Long‐term monitoring is especially important in evaluating restoration interventions that focus on indirect above‐ground–below‐ground linkages.

Nonlinear responses of foliar phenylpropanoids to increasing O3 exposure: Ecological implications in a Populus model system

Plant phenolic compounds (phenylpropanoids) act as defense chemicals against herbivores and can mediate ecosystem processes. Tropospheric ozone (O3) pollution alters concentrations of plant phenolics; however, little is known about how these phytochemicals respond to different levels of O3 exposure. Here, we investigated the effects of five different O3 exposure levels on foliar concentrations of phenylpropanoids (53 compounds in total) and antioxidative capacity in hybrid Populus (Populus euramericana cv. ‘74/76’) saplings grown in the presence of high or low soil nitrogen (N) load. Increasing O3 exposure initially increased and then decreased total concentrations of phenolic compounds, revealing a biphasic exposure-response profile (hormetic zone: 1.1–36.3 ppm h AOT40). This biphasic response pattern was driven by changes in a subset of phenylpropanoids with high antioxidative capacity (e.g. condensed tannins) but not in phenolics with low antioxidative capacity (e.g. salicinoids). The O3 exposure-response relationships of some phenylpropanoids (e.g. flavonoids and chlorogenic acids) varied in response to soil N, with hormesis occurring in high N soil but not in low N soil. Collectively, our findings indicated that plant phenolic compounds exhibit nonlinear responses to increasing O3 exposure, and that the responses vary in relation to phenolic compound class, antioxidative capacity, and soil nitrogen conditions. Our findings further suggest that the impact of O3 on ecological processes mediated by phenolics will be concentration-dependent, highlighting the complexity of the ecological effects of ground-level O3 pollution.

Genetics of extra-early-maturing yellow and orange quality protein maize inbreds and derived hybrids under low soil nitrogen and Striga infestation.

The development and commercialization of extra‐early quality protein maize (QPM)–provitamin A (PVA) hybrids that are tolerant of low soil N (LN) and Striga resistant are essential for addressing the food insecurity and undernourishment challenges currently faced by sub‐Saharan Africa (SSA). This study was designed (a) to determine the genetic effects regulating grain yield (GY) and important secondary traits of extra‐early yellow and orange QPM–PVA inbred lines under LN, Striga‐infested, and high‐N (HN) conditions, (b) to investigate whether maternal genes influenced the inheritance of GY and other secondary traits, (c) to assess the GY and stability of the hybrids across the three management conditions, and (d) to examine the relationship between single nucleotide polymorphism (SNP) marker‐based genetic distances and GY. Twenty‐four inbred lines were used to produce ninety‐six single cross hybrids using the North Carolina Design II. The performance of the hybrids plus four checks was assessed across LN, Striga‐infested, and HN management conditions in Ghana and Nigeria in 2018. Additive genetic variances were preponderant over nonadditive genetic variances for GY and most secondary traits in each and across environments. TZEEQI 358 exhibited significant and positive male and female GCA effects for GY under LN, Striga infestation, HN, and across management conditions indicating that favorable alleles for GY could be donated by TZEEQI 358. Maternal effects regulated the inheritance of plant height under the Striga‐infested conditions. Genetic distances were associated with GY under LN, Striga infestation, and HN conditions. TZEEIORQ 58 × TZEEQI 397 demonstrated high GY and stability of performance; therefore, it should be further tested under multiple environments for commercialization.

A Research on Herbal and Quality Properties of Lice Local Tobacco as Genetic Source

Tobaccos produced in Turkey are grouped under different names according to the different environmental properties and various characteristics of the regions where they were grown. Lice tobacco is an important local tobacco variety cultivated under Lice-Hazro and Kulp districts conditions. In recent years, a large number of tobacco origin and village populations disappeared from production and faced the danger of extinction. Especially the Lice local tobacco variety has gained a very good adaptation ability against the stress factors of the region. Different environmental factors such as high altitude, stony areas and high temperature, low rainfall and low nitrogen soils have determined the important quality characteristics that distinguish Lice tobacco from other tobacco types. The short plant height and reverse conical plant shape in Lice Tobacco produced in Lice District and around of Diyarbakır draws attention firstly. In Lice tobacco, the number of leaves per plant is 15-17 pieces / plant, the ratio of the length of the leaves to the width (38 cm / 23 cm), the elliptical leaf blade, dark green leaves and plant color, early flowering, the petal color is pinkish red. It is a local variety with high cigarette yield, low nicotine ratio (1-2%), protein nitrogen ratio 1%, total reducing substance ratio 15%, and the highest alkaloid ratio. In this study, the plant and quality characteristics of the local Lice tobacco variety, which has a high degree of genetic diversity, were investigated in farmer conditions and the differences with other Eastern and Southeastern Anatolian tobacco varieties were tried to be revealed.

The Impact of Domestication on Aboveground and Belowground Trait Responses to Nitrogen Fertilization in Wild and Cultivated Genotypes of Chickpea (Cicer sp.).

Despite the importance of crop responses to low fertility conditions, few studies have examined the extent to which domestication may have limited crop responses to low-fertility environments in aboveground and belowground traits. Moreover, studies that have addressed this topic have used a limited number of wild accessions, therefore overlooking the genotypic and phenotypic diversity of wild relatives. To examine how domestication has affected the response of aboveground and belowground agronomic traits, we measured root and leaf functional traits in an extensive set of wild and domesticated chickpea accessions grown in low and high nitrogen soil environments. Unlike previous studies, the wild accessions used in this study broadly capture the genetic and phenotypic diversity of domesticated chickpea’s (Cicer arietinum) closest compatible wild relative (C. reticulatum). Our results suggest that the domestication of chickpea led to greater capacities for plasticity in morphological and biomass related traits but may have lowered the capacity to modify physiological traits related to gas exchange. Wild chickpea displayed greater phenotypic plasticity for physiological traits including stomatal conductance, canopy level photosynthesis, leaf level photosynthesis, and leaf C/N ratio. In contrast to domesticated chickpea, wild chickpea displayed phenotypes consistent with water loss prevention, by exhibiting lower specific leaf area, stomatal conductance and maintaining efficient water-use. In addition to these general patterns, our results indicate that the domestication dampened the variation in response type to higher nitrogen environments for belowground and aboveground traits, which suggests reduced genetic diversity in current crop germplasm collections.

Nutrients cause grassland biomass to outpace herbivory

Human activities are transforming grassland biomass via changing climate, elemental nutrients, and herbivory. Theory predicts that food-limited herbivores will consume any additional biomass stimulated by nutrient inputs (‘consumer-controlled’). Alternatively, nutrient supply is predicted to increase biomass where herbivores alter community composition or are limited by factors other than food (‘resource-controlled’). Using an experiment replicated in 58 grasslands spanning six continents, we show that nutrient addition and vertebrate herbivore exclusion each caused sustained increases in aboveground live biomass over a decade, but consumer control was weak. However, at sites with high vertebrate grazing intensity or domestic livestock, herbivores consumed the additional fertilization-induced biomass, supporting the consumer-controlled prediction. Herbivores most effectively reduced the additional live biomass at sites with low precipitation or high ambient soil nitrogen. Overall, these experimental results suggest that grassland biomass will outstrip wild herbivore control as human activities increase elemental nutrient supply, with widespread consequences for grazing and fire risk.