Stem Elongation Stage Research Articles

Different responses of root exudates to biochar application under elevated CO2

Biochar application and rising carbon dioxide (CO2) concentrations are likely to influence both aboveground and belowground plant processes. However, little is known about the influence of biochar and CO2 enrichment on root exudation, as well as their interactive effects. The aim of this study was to reveal whether rice paddy root exudates responded to biochar and CO2 enrichment and whether this effect varied at different plant growth stages. Rice was grown in growth chambers with different biochar addition rates (1%, 2%, 3%, 4%, and 5% by weight) under both ambient (aCO2, 400 ppm) and elevated (eCO2, 700 ppm) CO2 levels. Root exudation variables were measured at the tillering and stem elongation stages. Electrical conductivity (EC), amino acid (AA), indole acetic acid (IAA), and abscisic acid (ABA) levels were significantly increased but cytokinin (CYT) concentrations decreased in response to biochar addition rates. In addition, eCO2 increased root and shoot biomass but decreased the root-to-shoot ratio. eCO2 significantly decreased EC, potassium (K+), ABA, and CYT concentrations, while the opposite pattern was found for AA and IAA. Significant interactive effects between biochar addition and eCO2 were only found on CYT and AA concentrations, while no significant interactive effects of plant growth stage, biochar addition, and eCO2 were found on root exudation. These results indicate that the additive effects of biochar and eCO2 should be integrated into assessments of carbon storage ability in the future. Understanding the different responses of these variables within the rhizosphere is crucial for predicting changes in the carbon balance in response to biochar application and climate change.

Soil microbial functional diversity and root growth responses to soil amendments contribute to CO2 emission in rainfed cropland

Carbon (C) losses induced by soil amendments have been shown to trigger soil conservation concerns. However, the mechanisms of fertilizer-induced CO2 emissions are still unclear. Here, we investigated the impact of soil nitrogen (N) amendments at an upland site on soil C stocks, CO2 emission, microbial functional diversity, and soil enzymatic activities during the stem elongation and harvest stages of rapeseed in 2016–2018. Five treatments were designed including non-N fertilizer (N0), conventional urea (U), monotypic CRU fertilization (CRU), co-application of U with CRU (CRC), and CRU plus organic fertilizer (CRO). The key finding is that the significant increases in CO2 emissions from CRO soils were ephemeral compared with the N0 treatment. Root biomass and root: shoot ratio partly explained the significant effect of N addition to CO2 production. Further, improved amylase activities and increasing consumptions of carboxylic acids, polymers and miscellaneous by soil microbes were mainly responsible for enhanced soil CO2 emissions in both growing seasons (P < 0.01). This suggests that fertilizer-induced CO2 emission could be regulated by soil C and N availability, which is attributed to the dynamic changes in soil carbon metabolism. During the stem elongation of 2016–2017, the consumption of carbohydrates, carboxylic acids, polymers, amines, and miscellaneous in CRO treatment during the first sampling phase was 21.65%, 41.36%, 17.98%, 27.61% and 49.52% higher than those in traditional urea fertilizer, respectively. Moreover, compared to the CRU, U, and N0 treatments, the CRO treatment significantly increased the McIntosh index during the stem elongation of both seasons. The results indicate that a sensitive and rapid indicator to finding a good soil N management is short-term alterations in the microbial functional diversity. Additionally, a broad spectrum of the utilization of substrates by soil bacteria was showed in CRO plots, irrespective of interannual variations of precipitation from 2016 to 2018. In contrast, non-N and conventional urea treatments produced a greater disparity in the utilization of carbon substrates from across all sampling times compared with CRU amended treatments, and both of them were less correlated with the most C-sources. Overall, single basal CRO fertilization, as a stable N source, can satisfy plant and soil microbial C and N demands, hence mitigating soil CO2 emission.

Optimizing irrigation strategies to synchronously improve the yield and water productivity of winter wheat under interannual precipitation variability in the North China Plain

The optimization of irrigation strategies with the goal of increasing water utilization efficiency and achieving higher yield is an important farming practice that helps balance groundwater use and food security during water shortage periods in the North China Plain (NCP). In the present study, the AquaCrop model was used to simulate winter wheat yield, evapotranspiration (ET), water productivity (WPET), and irrigation water productivity (IWP) under seven irrigation strategy scenarios and three precipitation categories. The results revealed that the annual precipitation fluctuated significantly over the past 35 years (1981–2015), leading to considerably varied irrigation water requirements with an average of 292 mm. The water consumption intensity of winter wheat tended to shift to the middle growing stage with an increase during the tillering-stem elongation stage and stem elongation-anthesis stage. Two irrigations at the stem elongation and anthesis stages significantly increased yield, WPET, and IWP with values of 7.79 t ha−1, 1.72 kg m-3, and 2.20 kg m-3, respectively, compared with those under lower irrigation frequency treatments. However, a significant decrease in IWP and nonsignificant difference in yield was found when further increasing the irrigation frequency. Combining the yield, WPET, and IWP results, the recommended optimal irrigation strategies for different precipitation categories are one irrigation at the anthesis stage for wet years with yield, WPET, and IWP values of 6.95 t ha−1, 1.49 kg m-3, and 1.73 kg m-3, respectively; two irrigations at the stem elongation and anthesis stages for normal years, which emphasizes meeting the water requirement during the tillering-stem elongation and heading-milk stages; and two irrigations for dry conditions/low precipitation, with emphasis on water requirements during the tillering-stem elongation stage. In conclusion, optimizing irrigation strategies according to precipitation categories can synchronously achieve the goals of increasing water utilization efficiency and achieving higher yield with respect to interannual precipitation variability, which promises to be a sustainable agricultural practice.

Estimation of winter wheat leaf area index at different growth stages using optimized red-edge hyperspectral vegetation indices

Leaf area index (LAI), as one of the most important indicators in vegetation growth monitoring, has been widely used in crop growth monitor and yield estimation. Previous studies focused on LAI retrieval for whole growth stages, this study inversed LAI at five main growth stages using widely-acknowledged vegetation indices and their optimized red-edge transformations. We used hyperspectral data to analyse relationships between LAI and vegetation indices. Partial least square discriminant analysis (PLS-DA) was used in this study to distinguish the best indices for distinct growth stages. The results show that LAI retrieval at various growth stages have distinct results. The best fitted indices for different growth stages are not fixed. The best indices for five stages are OSAVIre1, SRre1, SAVIre2, SAVIre2 and OSAVIre1 with R2 value of 0.20, 0.50, 0.49, 0.72 and 0.23, respectively. Most vegetation indices show better performance in milky stage than other four stages this may due to the high vegetation cover in this stage because leaves rise to maximum. Indices composed of red-edge exhibited better relationships with LAI with higher R2 and lower RMSE. Indices combined reflectance at 740 nm are capable of inversing LAI at stem elongation, anthesis and milk development stages. Indices with 705 nm showed better results in jointing and ripening stages. The results indicate that:1) specific vegetation indices for distinct growth stages lead to better estimation than inversing LAI for whole growth stages; 2) indices take advantage of red-edge showed better potentials in estimating high LAI than traditional visible wavelength.

Developing a Proximal Active Canopy Sensor-based Precision Nitrogen Management Strategy for High-Yielding Rice

RapidSCAN is a portable active canopy sensor with red, red-edge, and near infrared spectral bands. The objective of this study is to develop and evaluate a RapidSCAN sensor-based precision nitrogen (N) management (PNM) strategy for high-yielding rice in Northeast China. Six rice N rate experiments were conducted from 2014 to 2016 at Jiansanjiang Experiment Station of China Agricultural University in Northeast China. The results indicated that the sensor performed well for estimating rice yield potential (YP0) and yield response to additional N application (RIHarvest) at the stem elongation stage using normalized difference vegetation index (NDVI) (R2 = 0.60–0.77 and relative error (REr) = 6.2–8.0%) and at the heading stage using normalized difference red edge (NDRE) (R2 = 0.70–0.82 and REr = 7.3–8.7%). A new RapidSCAN sensor-based PNM strategy was developed that would make N recommendations at both stem elongation and heading growth stages, in contrast to previously developed strategy making N recommendation only at the stem elongation stage. This new PNM strategy could save 24% N fertilizers, and increase N use efficiencies by 29–35% as compared to Farmer N Management, without significantly affecting the rice grain yield and economic returns. Compared with regional optimum N management, the new PNM strategy increased 4% grain yield, 3–10% N use efficiencies and 148 $ ha−1 economic returns across years and varieties. It is concluded that the new RapidSCAN sensor-based PNM strategy with two in-season N recommendations using NDVI and NDRE is suitable for guiding in-season N management in high-yield rice management systems. Future studies are needed to evaluate this RapidSCAN sensor-based PNM strategy under diverse on-farm conditions, as well as to integrate it into high-yield rice management systems for food security and sustainable development.

Fine-mapping and transcriptome analysis of a candidate gene controlling plant height in Brassica napus L.

BackgroundBrassica napus provides approximately 13–16% of global vegetable oil for human consumption and biodiesel production. Plant height (PH) is a key trait that affects plant architecture, seed yield and harvest index. However, the genetic mechanism of PH in B. napus is poorly understood.ResultsA dwarf mutant df59 was isolated from a large-scale screening of an ethyl methanesulphonate-mutagenized rapeseed variety Ningyou 18. A genetic analysis showed that the dwarfism phenotype was controlled by one semi-dominant gene, which was mapped on C9 chromosome by quantitative trait loci sequencing analysis and designated as BnaDwf.C9. To fine-map BnaDwf.C9, two F2 populations were constructed from crosses between conventional rapeseed cultivars (Zhongshuang 11 and Holly) and df59. BnaDwf.C9 was fine-mapped to the region between single-nucleotide polymorphism (SNP) markers M14 and M4, corresponding to a 120.87-kb interval of the B. napus ‘Darmor-bzh’ genome. Within this interval, seven, eight and nine annotated or predicted genes were identified in “Darmor-bzh”, “Ningyou 7” and “Zhongshuang 11” reference genomes, respectively. In addition, a comparative transcriptome analysis was performed using stem tips from Ningyou 18 and df59 at the stem elongation stage. In total, 3995 differentially expressed genes (DEGs) were identified. Among them, 118 DEGs were clustered in plant hormone-related signal transduction pathways, including 81 DEGs were enriched in auxin signal transduction. Combining the results of fine-mapping and transcriptome analyses, BnaC09g20450D was considered a candidate gene for BnaDwf.C9, which contains a SNP that co-segregated in 4746 individuals. Finally, a PCR-based marker was developed based on the SNP in BnaC09g20450D.ConclusionsThe combination of quantitative trait loci sequencing, fine-mapping and genome-wide transcriptomic analysis revealed one candidate gene located within the confidence interval of 120.87-kb region. This study provides a new genetic resource for semi-dwarf breeding and new insights into understanding the genetic architecture of PH in B. napus.

Tiller development affected by nitrogen fertilization in a high‐yielding wheat production system

AbstractQuantitative understanding of how fertilizer N affects tiller development is essential for simultaneously achieving high yield and high N use efficiency in wheat (Triticum aestivum L.) production. A 3‐yr field experiment was conducted on the North China Plain during 2015–2017, with winter wheat grown at five fertilizer N rates (0–300 kg ha−1). The highest grain yield (∼9 Mg ha−1) was obtained at the optimized N rate (on average 160 kg ha−1, determined by subtracting the soil NO3− content from estimated N target values) and attributed to the high spike number, which was further contributed by the main stem (MS) and the fertile first tiller (T1). Greater N application than the optimized rate did not further increase grain yield but increased the biomass and N concentration of other tillers that were unproductive. The critical plant aboveground N concentrations (2.81% at stem elongation stage [Zadoks Growth Stage, GS 31] and 1.95% at anthesis (GS 64) and critical root‐zone soil mineral N content (Nmin) (74 kg ha−1 at GS 31 and 129 kg ha−1 at GS 64) for the attainable maximum stem number (1578 m−2 at GS 31 and 944 m−2 at GS 64) were quantified in this high‐yielding system. The critical plant aboveground N concentrations for achieving the maximal biomass of stem were also established to be 2.72% at GS 31 and 1.53% at GS 64, respectively. At these critical levels, the maximal biomass of MS and T1 were obtained without increasing the growth of the other tillers that were unproductive. Our results showed that high yield of winter wheat can be achieved by increasing the number of productive stems and the biomass per productive stem through optimizing the root‐zone Nmin and plant N concentrations.

Yeni ve Eski Buğday Çeşitlerinin Yüksek Yetişme Sıcaklığında Gelişimlerinin Karşılaştırılması

Buğdayda yaklaşık 10 bin yıldır doğal veya suni olarak yeni çeşitler ortaya çıkmaktadır. İnsanoğlu tarafından geliştirilen çeşitler de en önemli kriterler olarak verim, gübre ve makine kullanımı, değişen lezzet tercihleri ile iklim değişikliklerine uyum sayılabilir. Yapılan bu çalışmada; yeni geliştirilen çeşitlerden olan, vernalizasyon ve fotoperiyot hassasiyeti düşük USU-Apogee çeşidi ile daha önce geliştirilen çeşitlerden olan Einkorn ve Emmer ile yine ülkemizde geliştirilen alternatif gelişme tabiatlı Tosunbey çeşidi agronomik özellikler bakımından karşılaştırılmıştır. Araştırma oda sıcaklığında ve yazlık ekim olarak tarla koşullarında yürütülmüştür. Oda sıcaklığında yetiştirmede Apogee çeşidi 87 günde, Emmer çeşidi 140 günde, Tosunbey çeşidi 116 günde hasat olgunluğuna gelmiştir. Einkorn çeşidinin gelişimi vernalizasyon ihtiyacını karşılayamadığından dolayı sapa kalkma döneminde durmuştur. Tarla denemelerinde ise tüm çeşitler vernalizasyon ihtiyacını karşılayarak gelişimlerini tamamlamışlardır. Apogee çeşidi 93 günde, Einkorn çeşidi 118 günde, Emmer çeşidi 108 günde, Tosunbey çeşidi 115 günde hasat olgunluğuna gelmiştir. Apogee çeşidi arazi koşullarında daha geç olgunlaşırken, diğer çeşitler daha erken olgunlaşmışlardır. Oda sıcaklığında yetiştirmede bin tane ağırlıkları Apogee çeşidinde 24,2 g, Emmer çeşidinde 17,4 g, Tosunbey çeşidinde 26,5 g bulunurken, tarla denemelerinde Apogee çeşidinde 11,3 g, Einkorn çeşidinde 20,3 g, Emmer çeşidinde 24,7 g, Tosunbey çeşidinde 26,0 g olarak belirlenmiştir. Tarla denemelerinde Apogee çeşidinde bin tane ağırlığı belirgin olarak azalmıştır.

Impact of temperature and rainfall on rice production in Punjab, Pakistan

Rainfall pattern and temperature variation are changing due to global warming, affecting crop production. The purpose of this study is to investigate the impact of temperature and rainfall on rice production during the rice growth phases over the Punjab province, Pakistan, for the period of 1981–2017. The impact of climate on rice production is analyzed using the statistical techniques. Results show that maximum temperature negatively affects rice plant resulting in decrease in the number of plants at replantation stage. The positive impact of minimum temperature on rice production is also observed that may cause growth of plant, which affects the rice crop at replantation stage during vegetative phase. Results revealed that number of tillers and rice plant diet increase with the positive impact of rainfall at tillering stage. Maximum temperature has negative impact on rice crop at tillering and stem elongation stages. It is observed that rainfall has negative impact on rice plant at heading and flowering stages. Substantial reduction in rice production is observed due to damage of reproductive cells at heading and flowering stages during the reproductive phase. The negative effect of rainfall on rice production is also observed at milking stage during the ripening phase. The negative significant impact of rainfall is observed on gross domestic product per capita during the reproductive phase. This study also predicts that temperatures in the Punjab will rise in the near future; therefore, it is recommended that breeders should introduce rice varieties that consume less water and are more productive in high temperature.

Imaging Wheat Canopy Through Stereo Vision: Overcoming the Challenges of the Laboratory to Field Transition for Morphological Features Extraction.

Stereo vision is a 3D imaging method that allows quick measurement of plant architecture. Historically, the method has mainly been developed in controlled conditions. This study identified several challenges to adapt the method to natural field conditions and propose solutions. The plant traits studied were leaf area, mean leaf angle, leaf angle distribution, and canopy height. The experiment took place in a winter wheat, Triticum aestivum L., field dedicated to fertilization trials at Gembloux (Belgium). Images were acquired thanks to two nadir cameras. A machine learning algorithm using RGB and HSV color spaces is proposed to perform soil-plant segmentation robust to light conditions. The matching between images of the two cameras and the leaf area computation was improved if the number of pixels in the image of a scene was binned from 2560 × 2048 to 1280 × 1024 pixels, for a distance of 1 m between the cameras and the canopy. Height descriptors such as median or 95th percentile of plant heights were useful to precisely compare the development of different canopies. Mean spike top height was measured with an accuracy of 97.1 %. The measurement of leaf area was affected by overlaps between leaves so that a calibration curve was necessary. The leaf area estimation presented a root mean square error (RMSE) of 0.37. The impact of wind on the variability of leaf area measurement was inferior to 3% except at the stem elongation stage. Mean leaf angles ranging from 53° to 62° were computed for the whole growing season. For each acquisition date during the vegetative stages, the variability of mean angle measurement was inferior to 1.5% which underpins that the method is precise.

Remedial Application of Urea Eliminates Yield Losses in Wheat Waterlogged during Stem Elongation

Waterlogging remains a critical constraint to wheat production in areas with high rainfall. Exogenous application of nitrogen (N) can effectively diminish the adverse effects of waterlogging, but varies with specific events. To provide highly efficient remedial strategies, this pot study investigated the effects of urea application following 10 days of waterlogging initialing at the stem elongation stage (Zadoks growth stage, GS33). The remedial measures included foliar spray of urea solution at a single dose (0.108 g urea per pot) at the 0th day after finishing waterlogging (FU1) and twice at the 0th and 7th day (FU2), and soil surface spray of urea solution at single and double doses when soil water content was approximately 80% of field capacity (SU1 and SU2, respectively). Waterlogging significantly reduced grain yield, total N uptake, and N partial factor productivity (by 11%, 18%, and 11%, respectively), but subsequent remedial measures improved these to variable degrees. Reduction in grain yield owing to waterlogging could be effectively alleviated and even eliminated using these remediations. Grain yield and N partial factor productivity were higher under FU2 and SU2 than FU1 and SU1. Among all treatments, plants under SU2 exhibited the highest total N uptake and top-dressing N recovery. Diminished yield losses were attributed to (1) increased kernel number per spike resulting from increased spikelet fertility and kernel number per spikelet and (2) increased photosynthetic production by delaying senescence (improved chlorophyll content and maintained green leaf area) of the top leaves. This study suggests that urea application for a brief period of time following waterlogging during the stem elongation stage has remarkable remedial effects.

Identifying the Critical Stage Near Anthesis for Waterlogging on Wheat Yield and Its Components in the Yangtze River Basin, China

Frequent waterlogging near anthesis is a primary constraint for wheat production in the Yangtze River Basin, China. This study aimed to identify the critical stage for waterlogging on wheat yield and its components and identify the possible factors determining this stage. In the first experiment (E1), we evaluated three varieties and initiated a 10-day waterlogging starting at the stem elongation (S1), booting (S2), and anthesis (S3) stages. In the second experiment (E2), waterlogging was applied at the stem elongation (S1) and anthesis (S3) stages and for three durations (five, 10, and 15 days). In E1, waterlogging at S1 and S2 resulted in a lower grain yield than at S3. In the second year of E1, grain yield under waterlogging at S1 and S3 was similar but significantly lower than under waterlogging conditions at S2. Waterlogging at S1 and S2 greatly decreased the kernel number per spike and 1000-kernel weight, but waterlogging at S3 only decreased the 1000-kernel weight. Moreover, different varieties did not change the stages mostly reducing grain yield and yield components. In E2, grain yield decreased with prolonged exposure to waterlogging and was significantly lower under 15-day conditions than the five-day conditions. There was no significant interaction between the stage and duration of waterlogging. Finally, our results indicate that in yield formation, a greater reliance on kernel weight instead of the kernel number per spike can contribute to a reduction in yield loss for waterlogging at S1 and S2. This study, therefore, indicates that the stem elongation stage is the most affected by waterlogging.

Improving Unmanned Aerial Vehicle Remote Sensing-Based Rice Nitrogen Nutrition Index Prediction with Machine Learning

Optimizing nitrogen (N) management in rice is crucial for China’s food security and sustainable agricultural development. Nondestructive crop growth monitoring based on remote sensing technologies can accurately assess crop N status, which may be used to guide the in-season site-specific N recommendations. The fixed-wing unmanned aerial vehicle (UAV)-based remote sensing is a low-cost, easy-to-operate technology for collecting spectral reflectance imagery, an important data source for precision N management. The relationships between many vegetation indices (VIs) derived from spectral reflectance data and crop parameters are known to be nonlinear. As a result, nonlinear machine learning methods have the potential to improve the estimation accuracy. The objective of this study was to evaluate five different approaches for estimating rice (Oryza sativa L.) aboveground biomass (AGB), plant N uptake (PNU), and N nutrition index (NNI) at stem elongation (SE) and heading (HD) stages in Northeast China: (1) single VI (SVI); (2) stepwise multiple linear regression (SMLR); (3) random forest (RF); (4) support vector machine (SVM); and (5) artificial neural networks (ANN) regression. The results indicated that machine learning methods improved the NNI estimation compared to VI-SLR and SMLR methods. The RF algorithm performed the best for estimating NNI (R2 = 0.94 (SE) and 0.96 (HD) for calibration and 0.61 (SE) and 0.79 (HD) for validation). The root mean square errors (RMSEs) were 0.09, and the relative errors were &lt;10% in all the models. It is concluded that the RF machine learning regression can significantly improve the estimation of rice N status using UAV remote sensing. The application machine learning methods offers a new opportunity to better use remote sensing data for monitoring crop growth conditions and guiding precision crop management. More studies are needed to further improve these machine learning-based models by combining both remote sensing data and other related soil, weather, and management information for applications in precision N and crop management.

THE EFFECT OF FOLIAR APPLICATION OF AMINO ACIDS ON THEIR CONTENT AND COMPOSITION IN WINTER WHEAT GRAIN

Field experiments were carried out at the Experimental Station of Vytautas Magnus University (54º52′ N, 23º49′ E) in Lithuania. Winter wheat was grown on the background of N150P90K90 mineral fertilization and was additionally foliar-fertilized with different concentrations of amino acid solutions (0.5-3.0%) at stem elongation and heading stages. The study was aimed to establish protein content as well as quantitative and qualitative distribution of amino acids in winter wheat grain as influenced by fertilization with different concentrations of amino acids. Experimental evidence showed that solutions with different concentrations of amino acids applied at winter wheat stem elongation and heading stages increased grain protein content and total amino acids contents. Plants, fertilized with amino acids solutions at stem elongation stage accumulated higher protein content by on average 4.8%, at heading stage by 4.5% compared with the grain protein content of plants that had not received amino acids fertilization. The total amino acids content in winter wheat grain in response to amino acids applied at stem elongation stage increased by on average 2.0 g kg-1, at heading stage by 5.3 g kg-1. Nonessential and essential amino acids content in winter wheat grain was significantly increased by 2.5 and 3.0% amino acids solutions, applied at stem elongation stage by 0.5, 1.0, 1.5% amino acids solutions applied at heading stage. Winter wheat fertilization with amino acids solutions at stem elongation stage mostly increased the content of glutamic acid, at heading stage mostly increased the contents of glutamic, aspartic, valine, isoleucine, leucine, phenylalanine, methionine, threonine and lysine acids.

Effect of different rates of urea fertilization on yield and some biochemical and physiological properties of four wheat cultivars under two irrigation regimes

Drought stress is one of the most serious limitations for the growth and yield of wheat worldwide. Under changing climatic conditions, understanding the urea fertilizer requirement for wheat could be helpful for improving the quality and quantity of yield. The effects of different urea fertilizer levels were evaluated for some biochemical and physiological properties of four wheat cultivars under two irrigation regimes. This experiment was conducted in a split-split plot, randomized complete block design, with three replications. The main plots were irrigation (normal irrigation and irrigation terminated at the stem elongation stage). The experimental plots employed four wheat cultivars (‘Shirudi’, ‘Chamran’, ‘Chamran 2’, and ‘Sirvan’) and four levels of urea fertilizer treatment (0, 120, 240, and 360 kg ha&lt;sup&gt;−1&lt;/sup&gt;), at two locations, Khodayan (52°20' E, 29°8' N) and Nasrabad (52°64' E and 29°58' N), Fars Province, Iran. Results from the full analysis of variance across the two locations indicated considerable differences in yield parameters between irrigation, rates of urea application, and cultivars (&lt;em&gt;p&lt;/em&gt; &amp;lt; 0.01). Interaction effects of location, irrigation, cultivars, and urea levels were also significant for Chl &lt;em&gt;b&lt;/em&gt;, 1,000-seed weight, and seed yield (&lt;em&gt;p&lt;/em&gt; &amp;lt; 0.01). The data indicated that termination of irrigation led to a reduction in RWC (20%), total chlorophyll content (30%), carotenoids (19%), 1,000-seed weight (18%), grain yield (29%), and a promotion in ionic leakage (17%) and proline accumulation (4%), in comparison to the controls. According to these results, ‘Chamran’ and ‘Shirudi’ showed the greatest tolerance to reduced irrigation and that using 240 kg ha&lt;sup&gt;−1&lt;/sup&gt; urea may effectively moderate the adverse effects of this in these and other wheat cultivars.

Evaluating of soil sulphur forms changes in long-term field experiments of Látókép

The aim of this work was to evaluate the changes of different sulphur forms (soluble, adsorbed) in chernozem soil in a long-term field experiment supplied with increasing doses of NPK fertilizers for a long time. In addition, other objective of this study included the examination of the applicability of recommended extractants of the different sulphate fraction in Hungarian soils. A long-term field experiment was established at the Research Station of Látókép of the University of Debrecen in 1984. In addition to control, two levels of NPK fertilizer doses have been used with irrigated and non-irrigated variants. Winter wheat and corn were cropped in a crop rotation on plots. Soil samples were collected in three different development stages of winter wheat, at the stage of stem elongation (April), flowering (May) and ripening (June of 2018) from the topsoil (0–20 cm) of experiment plots. Water-soluble inorganic sulphate was extracted with 0.01M CaCl2 solutions. The soluble plus adsorbed sulphate was extracted with 0.016M KH2PO4 solution. Sulphate was measured by turbidimetric method. 0.01M CaCl2-SO42— ranged between 0.293–1.896 mg kg-1 and the 0.016 M KH2PO4-SO42- varied between 5.087–10.261 mg kg-1. The values of KH2PO4 SO42- was higher than that of CaCl2-SO42-, because KH2PO4 extracted the adsorbed and soluble fractions of sulphate, while CaCl2 extracted the soluble sulphate fraction. The amount of absorbed sulphate was calculated by the differences of KH2PO4- SO4 and CaCl2-SO4. The KH2PO4 characterizes mainly the adsorbed sulphate fraction much more than the water-soluble fraction. KCl is the most widely used extractant for the determination of plant available sulphate content of soil in Hungary; therefore, KCl-SO42- fraction also was determined. The KCl-SO42- ranged between 0.328–2.152 mg kg-1. The CaCl2-SO42- and KCl-SO42- fractions were compared and based on Pearson's linear correlation, moderate correlation was established (r=0.511) between them. In all three extractant (0.01M CaCl2, 1M KCl, 0.016 M KH2PO4) higher sulphate fractions were measured in the fertilized plots where superphosphate had been supplied for ages until 2010. The arylsulphatase activity of soil also was determined and ranged between 9.284 and 26.860 µg p-nitrophenol g-1 h-1. The lowest value was observed in the treatment with highest NPK2 dose, both in irrigated and non-irrigated areas.

Development of the limit values of micronutrient deficiency in soil determined using Mehlich 3 extractant for Polish soil conditions. Part I. Wheat

Abstract To implement the Mehlich 3 method in Polish agro-chemical laboratories, limit values for deficiency of B, Cu, Fe, Mn and Zn in soil for wheat were developed. The values were developed on the basis of 1921 fields with wheat, evenly distributed throughout Poland. Soil samples were collected from these fields in 2016, together with the plants growing on them, at the stage of stem elongation (BBCH 30/31). The concentration of micronutrients was determined in all soil and plant samples. In addition, pH, texture, and the content of organic carbon and available phosphorus were determined in soil samples. Moreover, grain yield after wheat harvest was estimated for all fields. Limit values were developed by two independent methods: 1) the regression equation method and 2) the so-called high yield method. In the first case, the limit microelement concentration in soil was calculated from the equation describing the relationship between the bioaccumulation factor (R/G) and a specific soil feature (n=1921). The bioaccumulation factor is the quotient of the concentration of a micronutrient in a plant (R) and its concentration in the soil (G) determined by the Mehlich 3 method. The equations were constructed using the Stagraphics program. For each micronutrient, 8 models were tested in search for the equation with the highest determination coefficient r2. Limit values were calculated after substituting the critical value of microelements in the plant (R) to the selected model and transforming the equation accordingly. The basis of the second method was to separate the “high yield group” ≥7.0 t ha−1 (n=578) from the entire data set. In this group, lower quintiles for the Mehlich 3-concentration of individual microelements in soil were calculated. The lower quintiles (QU1) were taken as limit values. It was assumed that QU1 is a good indicator of the lowest micronutrient concentration in the soil at which a yield of 7.0 t ha−1 or higher can be obtained. The comparison of the values calculated with the regression equations method and the high yield method showed their similarity, which confirmed the reliability of these values. The proposed values define the limit for low microelements concentration in soil determined with the Mehlich 3 method, below which wheat fertilization with these nutrients is recommended.

Effect of Dried Pig Manure Fertilization on Barley Macronutrients and Sodium in a Nitrate Vulnerable Zone

Dried pig manure (DPM) may be valorized as a fertilizer suitable for barley crop in nitrate vulnerable zones (NVZs). The aim of this study was determine the macronutrients and sodium contents in barley (Hordeum vulgare L.) resulting from its application in a NVZ in Fompedraza (Valladolid, Spain). DPM was applied at three rates (85, 133, and 170 kg N ha−1 year−1); the mineral fertilizer with a nitrification inhibitor was applied at two rates (90 and 108 kg N ha−1 year−1), and these were compared with the control treatment (without fertilization) in a randomized complete block design. Nutrients were monitored in four different plant growth stages and in grain over a 3-year period. DMP-based fertilization increased P and Na contents in plant and decreased those of Ca and Mg. These changes were only translated into a P increase in grain. The Na content in plant should not affect the final crop yield, making this waste management strategy viable even in NVZs. However, N content in plant in tillering and stem elongation stages was lower for DPM-based fertilization than for mineral fertilization, and so was the C content, both in plant and in grain. Since N content is a limiting factor for crop development, supplementary mineral fertilization would be advised to compensate for N immobilization if this organic waste material is to be valorized as a fertilizer.

Effects of drought at different periods of wheat development on the leaf photosynthetic apparatus and productivity

The problem of drought impact on crop productivity is especially relevant for the leading cereal – wheat, since significant cultivation areas of this crop are located in risky farming zones. The aim of our studies was to compare the peculiarities of drought impact during the period of vegetative growth and reproductive development on the chlorophyll content, activity of chloroplast antioxidant enzymes, the rate of carbon dioxide gas exchange and transpiration as well as productivity of the wheat plants. The studies were carried out on bread winter wheat plants (Triticum aestivum L.) of the Astarta and Natalka varieties grown in a pot experiment. The plants were watered daily to maintain the soil moisture level in the pots in the range 70–60% of field capacity. Drought treatment involving decrease in soil moisture to 30% of the field capacity was applied to some of the plants at late stem elongation stage (BBCH 37-45) and to other plants at heading-anthesis (BBCH 59-65) while control plants were watered as usual. After 7 days of drought, the watering of treated plants was resumed to maintain the soil moisture at the level of control plants until the harvest. The penultimate leaf at the late stem elongation stage and flag leaf at the heading–anthesis period were used for measurements of photosynthetic apparatus response to drought. Plants of both varieties treated at stem elongation stage showed lower decline in the photosynthetic activity, chlorophyll content and grain productivity than those treated at heading-anthesis. The results obtained indicated that photosynthetic apparatus of wheat has a higher drought tolerance at the stem elongation stage than during the heading-anthesis stage. Furthermore, plants stressed at the stem elongation stage revealed better compensatory growth of lateral productive shoots due to superior supply of plants with assimilates after drought termination. Astarta variety had a more drought-tolerant photosynthetic apparatus and higher grain productivity in both well-watered and drought conditions as compared to Natalka variety. The differences between varieties were more contrasting when drought was applied at heading-anthesis.

Influence of precipitations and sunshine hours on yield of paddy field grown wheat (Triticum aestivum L.) in Northern Kyushu, Japan

ABSTRACTRelationships between wheat (Triticum æstivum L.) yield components and growing season weather conditions (e.g. temperature, precipitation, and sunshine duration) were investigated for a rice-wheat rotation paddy system situated in Northern Kyushu, Japan over a 17-year period (2000–2016). A 1.0 mm increase in precipitation from 21 to 32 days after sowing decreased wheat yield by about 27 kg ha−1 at early seedling stage with one to two leaves (Zadoks (Z) growth stage Z1.1–1.2). Number of tillers and spikes showed significant negative correlations to the amount of precipitation during the period. An hour increase in mean daily sunshine hours from 94 to 111 days after sowing resulted in an 328 kg ha−1 rise in grain yield at stem elongation stage with the first and second node detection (Z3.1–3.2). The grain number per square meter also showed strong positive correlations to sunshine hours during the same period. However, this positive effect of sunshine was negated when precipitation exceeded about 30 mm during the early seedling stage. Consequently, precipitations at early seedling stage and sunshine hours at stem elongation stage mostly determined wheat yield in Northern Kyushu paddy field. Increasing precipitations during the early seedling stage highlights the pressing need for effective paddy field drainage management from wheat sowing through harvest.Abbreviations: CP: Chikushi Plains; FARC: Fukuoka prefectural Agriculture and Forestry Research Center; SARC: Saga prefectural Agricultural Research Center; DAS: days after sowing