Enhancement Of Grain Yield Research Articles

Nanotechnology in Agriculture: Manganese Ferrite Nanoparticles as a Micronutrient Fertilizer for Wheat.

Limited research has focused on nanoparticle (NP) applications' impact on edible wheat parts in a field environment. Here, we studied the nutritional quality of edible parts of wheat (Triticum aestivum L.) with a field experiment by spraying MnFe2O4 nanoparticles. Wheat was foliar sprayed with 0, 25, 50, and 100 mg/L composite manganese ferrite (MnFe2O4) NPs during 220 d of a growth period. Ionic controls were prepared using the conventional counterparts (MnSO4·H2O and FeSO4·7H2O) to compare with the 100 mg/L MnFe2O4 NPs. After three consecutive foliar applications, nanoparticles demonstrated a substantial elevation in grain yield and harvest index, exhibiting a noteworthy increase to 5.0 ± 0.12 t/ha and 0.46 ± 0.001 in the 100 mg/L NP dose, respectively, concomitant with a 14% enhancement in the grain number per spike. Fe, Mn, and Ca content in grain increased to 77 ± 2.7 mg/kg, 119 ± 2.8 mg/kg, and 0.32 ± 7.9 g/kg in the 100 mg/L NPs, respectively. Compared to the ion treatment, the 100 mg/L NP treatments notably boosts wheat grain crude protein content (from 13 ± 0.79% to 15 ± 0.58%) and effectively lowers PA/Fe levels (from 11 ± 0.7 to 9.3 ± 0.5), thereby improving Fe bioavailability. The VSM results exhibited a slight superparamagnetic behavior, whereas the grains and stems exhibited diamagnetic behavior. The results indicate that the nanomaterial did not accumulate in the grains, suggesting its suitability as an Fe and Mn-rich fertilizer in agriculture. Above all, the foliar application of nanocomposites increased the concentrations of Fe, Mn, and Ca in wheat grains, accompanied by a significant enhancement in grain yield. Therefore, the research results indicate that the foliar application of MnFe2O4 NPs can positively regulate wheat grains' nutritional quality and yield.

Impact of Duckweed (Lemna minor L.) Growing in Paddy Fields on Rice Yield and Its Underlying Causes

Duckweed growing in paddy fields (DGP) has substantially increased because of the effects of climate warming and/or eutrophication in irrigated water. Previous studies have primarily focused on investigating the effects of DGP as a nonchemical agent for enhancing rice productivity on nitrogen utilization in rice paddy fields. However, how DGP impacts rice yield remains poorly understood. Therefore, a field experiment with three representative rice cultivars was conducted to determine the effects of DGP on rice yield, considering ecological factors, photosynthetic capacity, spectral changes, and plant growth. The results showed that DGP significantly reduced the pH value by 0.6 and the daily water temperature by 0.6 °C, accelerated rice heading by 1.6 days and increased the soil and plant analyzer development (SPAD) and photosynthetic rate of leaves by 10.8% and 14.4% on average, respectively. DGP also markedly enhanced the values of various vegetation indices such as RARSc, MTCI, GCI, NDVI705, CI, CIrededge, mND705, SR705, and GM, and the first derivative curve of the rice canopy reflectance spectrum exhibited a ‘red shift’ phenomenon upon DGP treatment. Changes in the aforementioned factors may lead to average increases of 4.7% in plant height, 15.0% in dry matter weight, 10.6% in panicles m−2, 2.3% in 1000-grain weight, and ultimately a 10.2% increase in grain yield. The correlation observed suggested that the DGP-induced enhancement in grain yield can be achieved by reducing the pH and temperature of the paddy water, thus enhancing the SPAD value and photosynthesis of leaves and stimulating rice plant growth. These results could offer valuable theoretical support for the future sustainable development of agriculture and the environment through the biological synergy between rice and duckweed.

Enhancement of grain yield in rice under combined drought and high-temperature stress conditions by maintaining photosynthesis through antioxidant enzyme activities by melatonin

Enhancement of grain yield in rice under combined drought and high-temperature stress conditions by maintaining photosynthesis through antioxidant enzyme activities by melatonin

Modulation of soil aeration and antioxidant defenses with hydrogen peroxide improves the growth of winter wheat (Triticum aestivum L.) plants

Soils with subsurface drip irrigation are often characterized by hypoxia, which could impair the aerobic respiration of roots and the productive potential of crops. Irrigation with hydrogen peroxide oxygenated water (HPOW) is one way to improve soil aeration in the rhizosphere. However, few studies have focused on exploring the interaction of HPOW with soil aeration and productivity of crops. The current work aimed to investigate the effects of four levels of HPOW [0 ppm H2O2 solution (tap water) as a control (H0), 600 ppm, 800 ppm and 1000 ppm H2O2 solution (H600, H800 and H1000)] on irrigation water properties, soil aeration, antioxidant defenses, growth biomarkers and yield components in winter wheat (Triticum aestivum L.) plants. Results confirmed that dissolved oxygen (DO) concentrations in H600, H800 and H1000 were significantly increased by 52.10%–126.59% and surface tension coefficients were significantly decreased by 17.72%–31.60% as compared to H0. DO concentrations in soil solutions irrigated with H600, H800 and H1000 were significantly elevated by 9.78%–15.68% as compared to H0, and the maximum value equal to 7.44 mg L−1 was found at a soil depth of 20 cm. Further, H600 and H800 reduced concentrations of malondialdehyde and H2O2 in leaves, increased accumulation of proline and activities of antioxidant enzymes, and resulted in an enhancement in grain yield of 15.28% and 25.23%, respectively. Application of H1000 resulted in lower growth biomarkers and yield components due to oxidative stress induced by decreased activities of antioxidant enzymes and accumulation of proline as well as elevated levels of lipid peroxidation as compared to H600 and H800. The optimal regulation was achieved with the H800 treatment. Overall, HPOW improved the plants growth by modulating soil aeration and antioxidant defenses which enhanced tolerance to hypoxic stress.

The varying promotion effects of fulvic acid with different molecular weights on the enhancement of grain yield and quality of winter wheat

This study aims to verify the application effect of Fluvic acid (FA) with different molecular weights (MW) on the growth and quality of winter wheat. FA extracted from lignite was divided into 3 MWs (W1≤3000 D, 3000 D<W2≤10000 D, and W3>10000 D) by dialysis, and its structure was analyzed. Three application rates were set for each MW FA in the pot experiment, which were 10, 25 and 50 mg/kg in soil, respectively, and water was the control. There were significant interactive effects of MW and application rates of FAs. Compared with the control, all the FA treatments significantly increased grain yields, nitrogen uptake efficiencies, grain iron concentration, and soil available nitrogen concentration. Heatmap analysis revealed that the W1C2 (10 mg/kg W1) treatment had the most significant impacts for all analyzed indexes, whereas W3C3 (50 mg/kg W3) showed the weakest impacts. The results showed that at a low application rate (10 mg/kg in soil), the promotion effects of the three MW FAs were similar. W1 showed the most significant promotion effects, which was attributed to the combined effects of its lower MW and functional group characteristics.

Identification and Management of Ascochyta Blight of Chickpea (Cicer arietinum L.) Prevalent in Bundelkhand Region of Uttar Pradesh, India

Field investigations were carried out during rabi (October–March), 2020–21 and 2021–22 in major chickpea-growing areas of Banda, Mahoba, Hamirpur and Chitrakoot districts of Bundelkhand region of Uttar Pradesh, India to find out a suitable management strategy for ascochyta blight disease in standing crop conditions. A survey study was carried out during January–February, 2022 to find out the occurrence of ascochyta blight. The overall severity of ascochyta blight observed in four surveyed districts ranged between 15.82–17.50%. The pathogen exhibited floccose and white to pale olive colored colony with irregular white periphery on potato dextrose agar media after 14 days of incubation. Maximum growth (46.2 mm) of mycelia was recorded on oatmeal agar media followed by the growth of 43.2 and 40.4 mm obtained in malt extract agar media and potato dextrose agar media, respectively. In standing crop conditions, two sprays of combination of Tebuconazole 50%+Trifloxystrobin 25% WG @ 0.1% gave the maximum reduction in disease incidence (47.05%) and disease severity (63.86%) along with the highest enhancement in grain yield (54.81%), number of pods plant-1 (55.56%) and 100 grain weight (62.28%). Results revealed that ascochyta blight of chickpea was prevalent in Bundelkhand region of Uttar Pradesh. Oatmeal agar medium can be used for cultivation of Ascochyta rabiei. In field, ascochyta blight can be managed by two sprays of combination of Tebuconazole 50% + Trifloxystrobin 25% WG @ 500 g ha-1 at symptoms initiation and after 15 days of first spray.

Microbial consortia enhance the yield of maize under sub-humid rainfed production system of India

Plant beneficial microorganisms are being used to improve soil health and crop yield in different cropping systems. Maize is an important crop grown around the world for food, feed and raw material for various industries. The aim of the present study was to evaluate two microbial consortia viz., microbial consortia 1 (Pseudomonas putida P7 + Paenibacillus favisporus B30) and microbial consortia 2 (Pseudomonas putida P45 + Bacillus amyloliquefaciens B17) under field conditions for their suitability in improving maize yield under rainfed situations at Ballowal Saunkhri (Punjab) having sub-humid (Hot Dry) climatic conditions. Pooled analysis of three years field experiments data showed that, seed + soil application of microbial consortia 1 and 2 led to enhancement in grain yield of kharif maize by 27.78 and 23.21% respectively over uninoculated control. Likewise, significant increase in Benefit:Cost ratio as well as straw yield was also observed. The present investigation suggests that, microbial consortia would help in significantly improving the yield and economics of maize grown on inceptisols under rainfed conditions.

Identification of Drought Tolerant Rice Genotypes Based on Morpho-Physiological and Yield Traits Under Normal and Drought Stress Conditions

Water shortage is a serious climatic factor that drastically limits rice productivity. Thereupon, the development of better adapting rice genotypes under water deficit stress is imperious to maintain rice yield to ensure food security worldwide. The current study focused on genetic variability of morpho-physiological traits of rice to discover relationships between morpho-physiological and yield contributing traits under drought stress conditions in 24 rice genotypes during 2019 and 2020 seasons. Results showed highly significant mean squares of combined analysis for treatments and environment of all studied traits under normal and drought stress conditions. Results reported that the earliest rice cultivars were Giza177 and Giza179; however, the highest yield and its components traits were detected for Giza179, followed by Giza178, Sakha101 and Sakha108 under normal and water deficit conditions; moreover, generally, PCV was higher than GCV for all studied traits. High heritability coupled with high genetic advance was noted for plant height and relative water content under normal and drought conditions, suggesting a preponderance of additive gene action in expressing these traits that could be improved by selection in early segregating generations. While, high heritability coupled with moderate genetic advance was noticed for duration, grain yield/plant and harvest index under both conditions. Giza179 and Giza178 showed the best values for drought tolerance and were produced from same genetic background. Moreover, grain yield/plant showed a highly significantly positive correlated with panicle length, number of panicles/plant, panicle weight and 100-grain weight under normal and water deficit conditions; moreover, these traits were the main components of grain yield, so any selection based on these traits may lead to enhancement in grain yield. As a result, Giza178 and Giza179 varieties can be introduced as donors in breeding programs to tolerate water shortages to improve morphological and yield characteristics.

Heterosis for Nitrogen Use Efficiency of Maize Hybrids Enhanced over Decades in China

The nitrogen use efficiency (NUE) of modern maize hybrids has been greatly improved, but for decades, little was known on whether the NUE heterosis of maize hybrids had increased. A two-year field study was conducted on eight maize hybrids and their parental inbred lines from the 1970s to 2000s under two N levels (0, 150 kg N ha−1). These were the most popular hybrids in China’s main maize-growing areas at the time. The results showed that the yield of the maize hybrids increased significantly at an average rate of 37.5% every 10 years. The evolution of NUE heterosis was mainly related to the increased kernel number per ear. The absolute NUE heterosis (AHNUE) and the mid-parent NUE heterosis (MPHNUE) of maize hybrids increased by 151.4% and 76.4% in the past four decades, or an average rate of 2.11 kg kg−1 and 19.1% every 10 years. Based on the coefficient of determination, the contribution of the mid-parent nitrogen internal efficiency heterosis (MPHNIE) to MPHNUE (43–57%) was significantly higher than that of the mid-parent nitrogen recovery efficiency heterosis (MPHNRE) (19–32%), indicating that the evolution of maize NUE heterosis was mainly derived from its NIE heterosis evolution. The increase of NIE heterosis in the past 40 years was closely related to the increased heterosis of kernel number per ear, the pre-silking N accumulation and the post-silking N remobilization. Therefore, the enhancement of maize NUE heterosis can be attributed to (i) heterosis improvement in post-silking N remobilization, which results mainly from greater heterosis in pre-silking N accumulation; (ii) heterosis improvement in carbon and nitrogen sink capacity, which exhibit as heterosis enhancement in grain yield and grain nitrogen concentration. To further improve yield and NUE, the pre-silking N and carbon accumulation and post-silking N remobilization should both continue to increase in maize breeding. Our results will provide new insights into NUE and help breeders select genotypes with both higher yields and higher NUE for the future.

An early-morning flowering trait in rice can enhance grain yield under heat stress field conditions at flowering stage

An early-morning flowering (EMF) trait is supposed to be effective in enhancing grain yield due to mitigation of heat-induced spikelet sterility at flowering in rice. This study evaluated (i) phenotypic differences between a near-isogenic line carrying a QTL for EMF trait (designated as IR64 +qEMF3) and a recurrent parent, IR64, under wide variation in climates and (ii) whether the EMF trait can enhance grain yield under heat stress at flowering. IR64 +qEMF3 had significant earlier flower opening time (FOT) in diverse environmental conditions including temperate, subtropical, and tropical regions. FOT differentially responded to maximum and minimum air temperatures between genotypes. Under non-heat stress temperatures at flowering, IR64 +qEMF3 had similar grain yield to IR64 with minimal changes in yield components. Seven field trials in heat-vulnerable regions of Myanmar for multiple years showed that higher percentage of grain set contributed to the significantly higher grain yield in IR64 +qEMF3 when plants were exposed to daily maximum air temperatures around 36.1 °C or higher. Lower spikelet sterility in IR64 +qEMF3 was attributed to the earlier FOT during cooler early morning hours. This is the first field study that clearly demonstrates the enhancement of grain yield due to EMF trait under diverse heat stress field conditions at flowering.

Allele mining for the grain number gene An-1 in rice (Oryza sativa L.)

Rice yield has attained a plateau and hence the enhancement of grain yield is indispensable to feed the growing population, which could be achieved by the identification of superior alleles in the existing germplasm. Any variation in the pleiotropic gene, An-1 (yield gene) leads to enhanced grain number and grain size in rice. Hence, the gene was chosen for analyzing the allelic diversity/haplotype variation with 150 lines of 3K RG panel which revealed that, the gene An-1 has 20 Single Nucleotide Polymorphisms and 10 INDELs encompassing both intronic and exonic regions. The genotypes were divided into four haplotypes in the combination of seven SNPs with the maximum number of genotypes in the first haplotype and the least number of genotypes in fourth haplotype. From the study, H1 was identified as a superior haplotype. The haplo-pheno analysis identified the superior donors viz., SIGARDIS, GENIT and DAMNOEUB KAUN KHMOM harbouring superior haplotype combinations, which may be further utilized in haplotype-based breeding for the development of high yielding rice varieties. Key words: rice, An-1, grain number, haplotype, SNPs, allelic diversity.

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.

Genetic divergence and interrelationships for yield and yield attributing traits in horsegram

The present experiment was carried out to estimate the genetic diversity by cluster and Principal Component analyses for seven yield and yield attributing traits in 50 horse gram germplasm accessions and two checks during the late kharif, 2019. In correlation analysis, the grain yield was positively and significantly associated with test weight and number of pods which suggested the possibilities of improving grain yield by simultaneous improvement of these traits. Using cluster analysis, the accessions were grouped into five clusters. Based on the average cluster mean, the first cluster had high mean values for grain yield, the number of pods, test weight and plant height. The results of PCA revealed that, PC1, PC2, PC3 having eigenvalue greater than 1 contributed to the total variability of 82.69 per cent. Horse gram genetic improvement is receiving less attention from researchers across the globe. Using the results of this study, there is a tremendous space for genetic enhancement in grain yield of horsegram. Key wordsGenetic divergence, PCA, Correlation, Eigenvalue, Horsegram

Effect of substitution of chemical fertilizer by bioinoculants on plant performance and rhizospheric bacterial community: case study with Cajanus cajan.

Improper nutrient management is one of the major limitations linked with cultivation of Cajanus cajan. This calls for an urgent need for a promising alternative, employing both bioinoculants and chemical fertilizer. Present study attempted to understand the impact of bioinoculants {Azotobacter chroococcum, Bacillus megaterium, and Pseudomonas fluorescens (ABP)} as their mono-inoculations, triple-inoculation, and their combination with different doses of fertilizer on (a) plant parameters, (b) soil nitrogen (N) economy, (c) resident bacterial community, (d) genes and transcripts involved in N cycle, and to evaluate the extent to which fertilizer could be replaced by ABP without compromising on grain yield. Bradyrhizobium sp. was used in all the treatments (as it was recommended for C. cajan). Combined application of bioinoculants and 75% of recommended dose of fertilizer (RDF) led to 1.28-fold enhancement in grain yield as compared to RDF alone. Apart fromexerting a positive impact on grain yield, the combined application of ABP and fertilizer led to an improvement in soil fertility, and modified the culturablerhizospheric bacterial community involved in N cycle. Integrated use of bioinoculants and fertilizer led to better N substrate utilization and hence, metabolic diversity when compared with application of fertilizer alone. An increase in the transcripts of nifH gene at the harvest stagein the soil treated with ABP alone and its combination with fertilizer, over individual treatment withfertilizer was observed. The combined use of ABP and fertilizer shaped the resident bacterial community towards a more beneficial community, which helped in increasing soil nitrogen turnover and hence, soil fertility as a whole.

Gap analysis and economics of front line demonstrations in moth bean [Vigna aconitifolia (Jacq.) Marechal] under rainfed conditions of Rajasthan

Performance analysis in terms of gap analysis, yield enhancement and economic viability of improved production technologies of moth bean vis-à-vis farmers’ practice was evaluated through front line demonstrations at farmers’ field during kharif seasons of 2015, 2016 and 2018. The front line demonstrations were conducted by Krishi Vigyan Kendra, Bikaner-II, Rajasthan. Recommended technologies for the agro-climatic zone (Hyper Arid Partial Irrigated Plain Zone, numerated as IC) developed by the university were adopted in letter and spirit for cultivating moth bean. Improved varieties of moth bean recommended for the region viz., RMO 257, CAZRI Moth 2 and RMO 257 were grown under demonstrations. Selection of farmers’ were done following due technique of Participatory Rural Appraisal (PRA). The experimental results reveal that grain yield under demonstrations ranged from 520 to 610 kg/ha with a mean of 567 kg/ha. In per cent terms, scaling in productivity following improved technology ranged from 18.96 to 30.00% with an average value of 23.26% (over the Farmers’ practice). Moreover, average yield gaps for extension, technology and technology index were 50, 107 kg/ha and 8.11 per cent, respectively. Demonstration of improved technologies also fetched average gross (₹35,838/ha), net return (₹24,622/ha) and additional return (₹5,605/ha) in comparison to Farmers’ practice. Demonstration of improved technology also resulted in realizing higher incremental cost benefit ratio (4.8) and benefit: cost ratio (2.20) compared to the Farmers’ practice (1.89) during three years study period. This enhancement in grain yield and economics of moth bean under demonstrations clearly showed the impact of adoption of improved technology over farmers’ practice in Hyper Arid Partial Irrigated Plain Zone of Rajasthan.

Management of Root Rot (Rhizoctonia solani) of Mothbean through Bio-Agents

Root rot caused by Rhizoctonia solani is an important disease of mothbean, under severe infestation it causes 58-68 % losses in grain yield. Three-year field experiments were conducted in hot arid conditions at Bikaner, Rajasthan during kharif seasons with the objective to find out suitable eco-friendly management strategies for root rot. The experiment was conducted on cv. RMO-225 with six different combination of Trichoderma harzianum + Pseudomonas fluorescens bio- agents viz, seed treatment, soil treatment and their combinations against the root rot disease and compared with an untreated control. Results of experiment showed that all the treatments brought significant decline in disease incidence and consequently enhancement of grain yield compared to control. The treatment having combination of Trichoderma harzianum + Pseudomonas fluorescens seed treatment (4+4 g/kg seed) + soil application of T. harzianum + P. fluorescens (1.25 +1.25 kg in 50 kg FYM for each/ha) had minimum (21.78 %) root rot incidence, highest grain yield (10.56 q /ha) and net return (Rs. 14,338/ha). The T. harzianum seed treatment 8 g/kg seed + soil application of T. harzianum 2.5kg in 100 kg FYM/ha was the next best treatment with 25.56 per cent disease incidence and 9.42 q/ha of grain yield. These treatments can provide an effective, economical and eco- friendly management of root rot of mothbean for cultivators.

Induced Mutagenesis Enhances Lodging Resistance and Photosynthetic Efficiency of Kodomillet (Paspalum Scrobiculatum)

The present research was focused in the development of photosynthetically efficient (PhE) and non-lodging mutants by utilizing ethyl methane sulphonate (EMS) and gamma radiation in the kodomillet variety CO 3, prone to lodging. Striking variations in a number of anatomical characteristics of leaf anatomy for PhE and culm thickness for lodging resistance was recorded in M2 (second mutant) generation. The identified mutants were subjected to transcriptomic studies to understand their molecular basis. Expression profiling was undertaken for pyruvate phosphate dikinase (PPDK), Nicotinamide Adenine Dinucleotide Phosphate Hydrogen—(NADPH) and NADP-dependent malate dehydrogenase (NADP-MDH) in the mutants CO 3-100-7-12 (photosynthetically efficient) and in CO 3-200-13-4 (less efficient). For lodging trait, two mutants CO 3-100-18-22 (lodged) and CO 3-300-7-4 (non-lodged) were selected for expression profiling using genes GA2ox6 and Rht-B. The studies confirmed the expression of PPDK increased 30-fold, NADP-ME2 ~1-fold and NADP-MDH10 was also highly expressed in the mutant CO 3-100-7-12. These expression profiles suggest that kodomillet uses an NADP-malic enzyme subtype C4 photosynthetic system. The expression of Rht-B was significantly up regulated in CO 3-300-7-4. The study highlights the differential expression patterns of the same gene in different lines at different time points of stress as well as non-stress conditions. This infers that the mutation has some effect on their expression; otherwise the expression levels will be unaltered. Enhancement in grain yield could be best achieved by developing a phenotype with high PhE and culm with thick sclerenchyma cells.

The fate of 15N labeled urea in a soybean-wheat cropping sequence under elevated CO2 and/or temperature

Changing climate has direct linkage with growth and metabolism in plants and is likely to alter nitrogen (N) uptake from fertilizers. Hence, a field study was conducted using 15N labeled urea in micro-plots to study the effects of elevated CO2 and/or temperature on fertilizer-N use in a soybean-wheat cropping sequence. Crops were grown in open top field chambers (OTCs) under two CO2 (386 and 558–561 ppmv), two temperature (ambient, 1.4-1.5 °C above) and three N levels during 2017-18. The N treatments were 50, 100 and 150% of the recommended dose (N50, N100 and N150). Labeled (15N) urea (10% atom excess) was applied to soybean. Elevated CO2 and/or temperature showed significant effects on seed yield, total N uptake, fertilizer-N uptake, per cent N derived from fertilizer (Ndff) and per cent fertilizer-N use in the soybean-wheat crop sequence. Total N uptake in soybean significantly increased under elevated CO2 and/or temperature treatments, mainly due to higher N uptake in seeds. Effect of climate on fertilizer-N uptake and utilization in the soybean-wheat cropping sequence varied with level of N application. The 15N labeled fertilizer-N uptake and per cent fertilizer-N use was significantly higher under co-elevation of both CO2 and temperature at N100 and N150, but, was mostly similar among the climate treatments at N50. In the soybean-wheat crop sequence, 13–40% of the applied fertilizer was used, with significantly higher use with co-elevation of both CO2 and temperature. Out of the applied fertilizer, 20–51% got retained in the surface soil and 43–73% was traced in the soil-plant system. Significantly higher fertilizer-N use in the soybean-wheat crop sequence under co-elevation of CO2 and temperature indicates increasing role of fertilizer-N to harvest the CO2 mediated enhancement in grain yield under the future climate conditions.

The Stimulatory Effects of Nanochitin Whisker on Carbon and Nitrogen Metabolism and on the Enhancement of Grain Yield and Crude Protein of Winter Wheat.

Nanochitin whisker (NC) with a cationic nature could enhance plant photosynthesis, grain yield, and quality of wheat, but have not been systematically studied. This study was designed to investigate the stimulatory effects of NC on dry matter (DM) and nitrogen (N) accumulation and translocation, and on the metabolism of carbon (C) and N in later growth stages of winter wheat to reveal the enhancement mechanism of grain yield and crude protein concentration. Different parts of NC-treated plants from pot grown experiments were collected at the pre- and post-anthesis stages. The accumulation, translocation, and contributions of DM and N from pre-anthesis vegetation organs to grains, as well as key metabolic enzyme activities, including sucrose phosphate synthase (SPS) and phosphoenolpyruvate carboxylase (PEPC), were examined. The results showed that, at an application rate of 6 mg·kg−1 of NC in the soil, the accumulation of DM and N were significantly enhanced by 16.2% and 38.8% in pre-anthesis, and by 15.4% and 30.0% in post-anthesis, respectively. Translocation of N and DM in the post-anthesis periods were enhanced by 38.4% and 50.9%, respectively. NC could also stimulate enzyme activities, and increased 39.8% and 57.1% in flag leaves, and by 36.0% and 58.8% in spikes, respectively, at anthesis. SPS and PEPC increased by 28.2% and 45.1% in flag leaves, and by 42.2% and 56.5% in spikes, respectively, at 15 days after anthesis. The results indicated that the NC promoted N metabolism more than C metabolism, and resulted in the enhancement of grain yield by 27.56% and of crude protein concentration in grain by 13.26%, respectively.

Identification of Quantitative Trait Loci Associated with Nutrient Use Efficiency Traits, Using SNP Markers in an Early Backcross Population of Rice (Oryza sativa L.).

The development of rice cultivars with nutrient use efficiency (NuUE) is highly crucial for sustaining global rice production in Asia and Africa. However, this requires a better understanding of the genetics of NuUE-related traits and their relationship to grain yield. In this study, simultaneous efforts were made to develop nutrient use efficient rice cultivars and to map quantitative trait loci (QTLs) governing NuUE-related traits in rice. A total of 230 BC1F5 introgression lines (ILs) were developed from a single early backcross population involving Weed Tolerant Rice 1, as the recipient parent, and Hao-an-nong, as the donor parent. The ILs were cultivated in field conditions with a different combination of fertilizer schedule under six nutrient conditions: minus nitrogen (–N), minus phosphorus (–P), (–NP), minus nitrogen phosphorus and potassium (–NPK), 75% of recommended nitrogen (75N), and NPK. Analysis of variance revealed that significant differences (p < 0.01) were noted among ILs and treatments for all traits. A high-density linkage map was constructed by using 704 high-quality single nucleotide polymorphism (SNP) markers. A total of 49 main-effect QTLs were identified on all chromosomes, except on chromosome 7, 11 and 12, which are showing 20.25% to 34.68% of phenotypic variation. With further analysis of these QTLs, we refined them to four top hotspot QTLs (QTL harbor-I to IV) located on chromosomes 3, 5, 9, and 11. However, we identified four novel putative QTLs for agronomic efficiency (AE) and 22 QTLs for partial factor productivity (PFP) under –P and 75N conditions. These interval regions of QTLs, several transporters and genes are located that were involved in nutrient uptake from soil to plant organs and tolerance to biotic and abiotic stresses. Further, the validation of these potential QTLs, genes may provide remarkable value for marker-aided selection and pyramiding of multiple QTLs, which would provide supporting evidence for the enhancement of grain yield and cloning of NuUE tolerance-responsive genes in rice.