Improving fertilizer recommendations for Nepalese farmers with the help of soil-testing mobile van

Smallholder farmers dominate agriculture in Nepal. These farmers have poor knowledge about agriculture and lack of support for soil management and integrated plant-nutrient systems. Focusing on the importance and need for soil-fertility management, a soil-testing mobile van program has recently been introduced in Nepal by Soil Management Directorate, Hariharbhawan. With the introduction of the mobile lab, famers can get their soil tested for nutrient deficiencies and fertilizer requirements at their doorsteps. Using mobile lab, spatial distributions of chemical properties, including pH, organic matter (OM), total nitrogen (N), available phosphorus (as P2O5), and available potassium (as K2O) were examined in soil samples taken from the 0 to 15 cm depth from selected agricultural fields in eight different districts in the mid-hills and Terai regions of Nepal. Tests conducted on 1,479 soil samples in the soil-testing mobile van revealed the following: the mean soil OM ranged from 0.01 to 1.77%; total N content ranged from 0.01 to 0.08%; mean available P2O5 ranged from 16.47 to 197.82 kg ha−1; and mean available K2O ranged from 84.3 to 422.57 kg ha−1. For each crop to be grown, farmers were provided with individual soil health reports and fertilizer recommendations (rate, amount, and type). This program not only allows scientists and farmers to work closely and share information but also serves as a model for the nation to successfully transfer technology for improving soil health and sustainability

Improving fertilizer recommendations for Nepalese farmers with the help of soil-testing mobile van

Smallholder farmers dominate agriculture in Nepal. These farmers have poor knowledge about agriculture and lack of support for soil management and integrated plant-nutrient systems. Focusing on the importance and need for soil-fertility management, a soil-testing mobile van program has recently been introduced in Nepal by Soil Management Directorate, Hariharbhawan. With the introduction of the mobile lab, famers can get their soil tested for nutrient deficiencies and fertilizer requirements at their doorsteps. Using mobile lab, spatial distributions of chemical properties, including pH, organic matter (OM), total nitrogen (N), available phosphorus (as P2O5), and available potassium (as K2O) were examined in soil samples taken from the 0 to 15 cm depth from selected agricultural fields in eight different districts in the mid-hills and Terai regions of Nepal. Tests conducted on 1,479 soil samples in the soil-testing mobile van revealed the following: the mean soil OM ranged from 0.01 to 1.77%; total N content ranged from 0.01 to 0.08%; mean available P2O5 ranged from 16.47 to 197.82 kg ha−1; and mean available K2O ranged from 84.3 to 422.57 kg ha−1. For each crop to be grown, farmers were provided with individual soil health reports and fertilizer recommendations (rate, amount, and type). This program not only allows scientists and farmers to work closely and share information but also serves as a model for the nation to successfully transfer technology for improving soil health and sustainability

Alteration in Intra-plant Distribution of δ15N in Response to Shading in Legumes

The intra-plant distribution of 15N in common bean, cowpea and soybean having different levels of responses to shading and N2-fi xing ability were analyzed under shaded and non-shaded conditions. Maize was used as a reference (non N2-fixing) plant. Seedlings were grown in pot soils for 3 weeks then transferred to shaded (55% of control) and non-shaded (control) conditions in a greenhouse, and sampled at 13 days and 24 days after shading. The proportion of plant N derived from N2-fixation (%Ndfa) estimated by the natural 15N abundance method was higher in cowpea and soybean (74.91%) than in common bean (37.38%). Shade treatment reduced %Ndfa signifi cantly in cowpea and soybean. The difference in δ15N between shoot and root (Δδ 15Ns-r) was the highest in maize followed by common bean, cowpea and soybean. Shading increased Δδ 15Ns-r in each legume species, particularly in cowpea and soybean. A signifi cant negative correlation was found between Δδ 15Ns-r and %Ndfa in all legumes at both sampling dates (R2 = 0.67.0.96, P<0.1). The slope and Y-intercept of the regression line was similar at the sampling dates, but varied with the species. The slope was –0.05 in cowpea, –0.06 in common bean, and –0.11 in soybean. The Δδ 15Ns-r value estimated by extrapolation of the regression line was 2.9, 2.5 and 8.6%. at 0 %Ndfa, and –3.2, –2.8 and –2.6%. at 100 %Ndfa, in common bean, cowpea and soybean, respectively. The consistent relationships between Δδ 15Ns-r and %Ndfa found among legume species suggest that Δδ 15Ns-r could be used as a parameter for estimating %Ndfa without using a reference plant, although the component of regression line was characteristically different among legume species

Difference in δ15N Signatures among Plant Parts of PerennialSpecies Subjected to Drought Stress with Special Referenceto the Contribution of Symbiotic N2-fixation to Plant N

The 15N natural abundance method has been widely used for evaluation of symbiotic N2-fixation. The method inevitably requires a reference plant that reflects soil derived δ15N similar to that in a N2-fixing target plant, for estimating the contribution of fixed N2. However, it is often difficult to select a suitable reference plant. Recently, an alternative method was proposed using the difference in δ15N values between shoots and nodulated roots, which did not require a reference plant per se. Whether this method is applicable to a wide range of N2-fixing plants having different growth habits and symbiosis types remains to be verified. To test the applicability of this method for perennial plants, we examined the difference in δ15N values between shoot and nodulated root (∆δ15Ns-nr), and that between shoot and root (∆δ15Ns-r) in 6-month-old plants grown in pots with different soil moisture regimes. The relationships between ∆δ15Ns-nr and the percentage of N derived from atmospheric N2 (%Ndfa) calculated from the conventional 15N natural abundance method, and between ∆δ15Ns-r and %Ndfa were analyzed in N2-fixing legume Lespedeza cuneata and N2-fixing non-legume Elaeagnus pungens and Myrica rubra. A close correlation was found between ∆δ15Ns-nr and %Ndfa as well as between ∆δ15Ns-r and %Ndfa in Lespedeza cuneata, while no correlation was found in N2-fixing non-legume species. The results indicated that ∆δ15N signatures could be useful for estimating %Ndfa for N2-fixing perennial legume (Lespedeza cuneata) in the first growth season but might not be applicable for N2-fixing actinorhizal plants

Plant Histone HTB (H2B) Variants in Regulating Chromatin Structure and Function

Besides chemical modification of histone proteins, chromatin dynamics can be modulated by histone variants. Most organisms possess multiple genes encoding for core histone proteins, which are highly similar in amino acid sequence. The Arabidopsis thaliana genome contains 11 genes encoding for histone H2B (HTBs), 13 for H2A (HTAs), 15 for H3 (HTRs), and 8 genes encoding for histone H4 (HFOs). The finding that histone variants may be expressed in specific tissues and/or during specific developmental stages, often displaying specific nuclear localization and involvement in specific nuclear processes suggests that histone variants have evolved to carry out specific functions in regulating chromatin structure and function and might be important for better understanding of growth and development and particularly the response to stress. In this review, we will elaborate on a group of core histone proteins in Arabidopsis, namely histone H2B, summarize existing data, and illuminate the potential function of H2B variants in regulating chromatin structure and function in Arabidopsis thaliana

Seasonal Growth of Zygophyllum dumosum Boiss.: Summer Dormancy Is Associated with Loss of the Permissive Epigenetic Marker Dimethyl H3K4 and Extensive Reduction in Proteins Involved in Basic Cell Functions

Plants thriving in desert environments are suitable for studying mechanisms for plant survival under extreme seasonal climate variation. We studied epigenetic mechanisms underlying seasonal growth cycles in the desert plant Zygophyllum dumosum Boiss., which was previously shown to be deficient in repressive markers of di-methyl and tri-methyl H3K9 and their association with factors regulating basic cell functions. We showed a contingent association between rainfall and seasonal growth and the epigenetic marker of dimethyl H3K4, which disappears upon entry into the dry season and the acquisition of a dormant state. DNA methylation is not affected by a lack of H3K9 di-methyl and tri-methyl. Changes in methylation can occur between the wet and dry season. Proteome analysis of acid soluble fractions revealed an extensive reduction in ribosomal proteins and in proteins involved in chloroplasts and mitochondrial activities during the dry seasons concomitantly with up-regulation of molecular chaperone HSPs. Our results highlight mechanisms underlying Z. dumosum adaptation to seasonal climate variation. Particularly, summer dormancy is associated with a loss of the permissive epigenetic marker dimethyl H3K4, which might facilitate genome compaction concomitantly with a significant reduction in proteins involved in basic cell functions. HSP chaperones might safeguard the integrity of cell components

MOESM1 of Arabidopsis mutants may represent recombinant introgression lines

Additional file 1. List of primers used in this study

Endophytic Bacteria Colonizing the Petiole of the Desert Plant <i>Zygophyllum dumosum</i> Boiss: Possible Role in Mitigating Stress

Zygophyllum dumosum is a dominant shrub in the Negev Desert whose survival is accomplished by multiple mechanisms including abscission of leaflets to reduce whole plant transpiration while leaving the fleshy, wax-covered petioles alive but dormant during the dry season. Petioles that can survive for two full growing seasons maintain cell component integrity and resume metabolic activity at the beginning of the winter. This remarkable survival prompted us to investigate endophytic bacteria colonizing the internal tissues of the petiole and assess their role in stress tolerance. Twenty-one distinct endophytes were isolated by culturing from surface-sterile petioles and identified by sequencing of the 16S rDNA. Sequence alignments and the phylogenetic tree clustered the isolated endophytes into two phyla, Firmicutes and Actinobacteria. Most isolated endophytes displayed a relatively slow growth on nutrient agar, which was accelerated by adding petiole extracts. Metabolic analysis of selected endophytes showed several common metabolites whose level is affected by petiole extract in a species-dependent manner including phosphoric acid, pyroglutamic acid, and glutamic acid. Other metabolites appear to be endophyte-specific metabolites, such as proline and trehalose, which were implicated in stress tolerance. These results demonstrate the existence of multiple endophytic bacteria colonizing Z. dumosum petioles with the potential role in maintaining cell integrity and functionality via synthesis of multiple beneficial metabolites that mitigate stress and contribute to stress tolerance

CMT3 and SUVH4/KYP silence the exonic Evelknievel retroelement to allow for reconstitution of CMT1 mRNA

Abstract Background The Chromomethylase 1 (CMT1) has long been considered a nonessential gene because, in certain Arabidopsis ecotypes, the CMT1 gene is disrupted by the Evelknievel (EK) retroelement, inserted within exon 13, or contains frameshift mutations, resulting in a truncated, non-functional protein. In contrast to other transposable elements, no transcriptional activation of EK was observed under stress conditions (e.g., protoplasting). Results We wanted to explore the regulatory pathway responsible for EK silencing in the Ler ecotype and its effect on CMT1 transcription. Methylome databases confirmed that EK retroelement is heavily methylated and methylation is extended toward CMT1 downstream region. Strong transcriptional activation of EK accompanied by significant reduction in non-CG methylation was found in cmt3 and kyp2, but not in ddm1 or RdDM mutants. EK activation in cmt3 and kyp2 did not interfere with upstream CMT1 expression but abolish transcription through the EK. We identified, in wild-type Ler, three spliced variants in which the entire EK is spliced out; one variant (25% of splicing incidents) facilitates proper reconstitution of an intact CMT1 mRNA. We could recover very low amount of the full-length CMT1 mRNA from WT Ler and Col, but not from cmt3 mutant. Conclusions Our findings highlight CMT3-SUVH4/KYP as the major pathway silencing the intragenic EK via inducing non-CG methylation. Furthermore, retroelement insertion within exons (e.g., CMT1) may not lead to a complete abolishment of the gene product when the element is kept silent. Rather the element can be spliced out to bring about reconstruction of an intact, functional mRNA and possibly retrieval of an active protein