Booting Stage Research Articles

Insights of Improved Aroma under Additional Nitrogen Application at Booting Stage in Fragrant Rice.

Plant mineral nutrition substantially affects the growth, yield and quality of rice, whereas nitrogen (N) application contributes significantly in this regard. Undoubtedly, N application improves rice aroma biosynthesis; however, the molecular mechanism underlying the regulation of grain 2-acetyl-1-pyrroline (2-AP) biosynthesis in the presence of nitrogen application at the booting stage has remained largely unexplored. The present study examined the effects of three N levels, i.e., 0 g per pot (N0), 0.43 g per pot (N1) and 0.86 g per pot (N2) on intermediates, enzymes and genes involved in 2-AP biosynthesis, as well as on the yield of two fragrant rice cultivars viz, Meixiangzhan2 and Xiangyaxiangzhan. N was additionally applied at the booting stage. The results depicted that the levels of precursor, such as proline, and the activity of enzymes involved in 2-AP biosynthesis, such as Δ1-pyrroline-5-carboxylate synthetase (P5CS) and diamine oxidase (DAO), and P5CS1 gene expression were comparatively higher under N1 than N0 in both fragrant rice cultivars. Moreover, the N2 treatment increased the grain panicle-1, filled grain percentage and grain yield of both rice cultivars, while the grain yield of Meixiangzhan2 and Xiangyaxiangzhan was increased by 15.87% and 12.09%, respectively, under N2 compared to N1 treatment. Hence, 0.43 g per pot of N showed positive performances in yield and aroma accumulation in fragrant rice and should be further employed in the practice and production for better cultivation in the rice market.

Effects of chilling at different growth stages on rice photosynthesis, plant growth, and yield

Chilling is the main limiting factor for rice production in high-altitude and high-latitude regions. Many studies have reported the impacts of chilling on leaf photosynthesis and biomass accumulation, but few of them explored the response of photosynthesis to chilling at different growth stages of rice and whether the decrease of photosynthesis at each stage is caused by stomatal or non-stomatal limiting factor. In order to achieve high grain yield for rice, it is critical to understand how chilling affects leaf photosynthesis and plant growth. In this study, we conducted a two-year field experiment (in 2018 and 2019) to investigate the effects of chilling at booting, flowering, and grain filling stages on leaf photosynthesis, plant growth, and grain yield for a japonica rice cultivar (Songjing6). At each target growth stage, the treatment included four chilling temperatures (12, 15, 18, and 21 ℃, respectively) and four chilling durations (2, 4, 6, and 8 days, respectively). The results showed that rice photosynthesis gradually decreased as the chilling temperature was decreasing and the chilling duration was increasing. The net photosynthetic rate decreased the most at the booting stage, followed by the flowering stage, and the grain filling stage. Compared with the chilling treatment at 2 days, the chilling treatment at 12, 15, and 18 ℃ for 4, 6, and 8 days reduced net photosynthetic rate by 15.1–36.1 %, 18.7–27.2 %, and 15.2–17.2 % at the booting, flowering, and grain filling stages, respectively. The chilling-induced decrease in net photosynthetic rate was mainly attributed to stomatal limiting factor at the booting and flowering stages but non-stomatal limiting factor at the grain filling stage. During the chilling treatment, the available light for rice plants was reduced and the rice plants were impaired in their ability to use weak light. The decrease in photosynthesis lead to reduced leaf source capacity and crop growth rate, hence the reduced aboveground biomass and increased source and sink increment ratio, and ultimately decreased the grain yield for rice. Our results indicate that maintaining efficient photosynthetic functioning at the booting and flowering stages is the key to combat chilling stress for rice. • Chilling decreased the net photosynthetic rate of rice most at the booting stage, followed by the flowering stage and the grain filling stage. • Chilling-induced decrease in the net photosynthetic rate was mainly attributed to stomatal limiting factor at the booting and flowering stages, but non-stomatal limiting factor at the grain filling stage. • The simulation of light response curve showed chilling at the booting and flowering stages decreased photosynthetic capacity and photosynthetic effective time，while chilling mainly affects the ability of using strong light at the grain filling stage.

Rice demands higher nitrogen fertilizer during grain filling stage under elevated atmospheric CO2 condition

An experiment was conducted in open top chamber (OTC) to determine the response of rice to elevated carbon dioxide (eCO2) under varying time of nitrogen (N) application. Rice was grown in OTC with 500 ppm CO2 (eCO2), 450 ppm CO2 (intermediate CO2, iCO2), ambient CO2 (aCO2) and open field (OF, 380 ppm CO2). The timings of N application were N1 = 1/3rd N at early tillering (ET) + 1/3rd at active tillering (AT) + 1/3rd before panicle initiation (PI) stage, N2 = 1/3rd N at ET + 1/3rd before PI + 1/3rd at booting stage (BS), and N3 = 1/3rd N at ET + 1/3rd before PI + 1/3rd at flowering stage (FS). The results revealed that photosynthesis (Pn), shoot and root dry matter (SDM and RDM) production, yield and yield components were favored at eCO2 when N application scheduled from ET to FS of rice. Interestingly, the N application up to FS of rice showed significant improved grain fertility and reduced sterility under rising CO2. However, rice plant accumulated and translocated more nutrients from shoot to grain under elevated CO2 (eCO2) condition. Moreover, higher grain amylose and lower protein was obvious at eCO2. Collectively, rice yield increased by 18 to 20 % under eCO2 with the application of N at FS of rice. These results indicate that to maximize rice yield under eCO2, it is crucial to supply N at FS of rice in order to increase grain fertility and reduce spikelet sterility

Estimating leaf nitrogen content by coupling a nitrogen allocation model with canopy reflectance

The area-based leaf nitrogen content (LNCA) has gained increasing attention recently in ecology and plant physiology, and the mass-based nitrogen content (LNCM) has been extensively used by agronomists for making fertilization recommendations. Remote sensing has been emerging as an important tool to quantify LNCA and LNCM across multiple observation scales, such as leaf and canopy. Most models for estimating LNCA and LNCM are based on their empirical relationships with chlorophyll-related vegetation indices (VIs), which cannot capture the dynamic allocation of nitrogen into different components throughout the growing season. This study proposed a simplified nitrogen allocation model by dividing the total nitrogen into photosynthetic nitrogen (PN) and non-photosynthetic nitrogen with the purpose of estimating LNCA and LNCM in rice and winter wheat. The nitrogen allocation model was calibrated with an independent leaf-scale dataset (R2 = 0.82) and then applied to the canopy scale without the need to adjust the model coefficients. The estimated fractions of PN were 71% and 78% for rice and wheat leaves, respectively, which were close to the reported value (∼75%) for common C3 plants. Overall, the nitrogen allocation-based models were applicable for estimating both LNCA and LNCM with relative root mean square error (RRMSE) values <15% for the jointing and booting stages. In addition, our novel estimation model was generic for rice and wheat, yielding the best estimations for LNCM (R2 = 0.63) across the entire growing season compared with traditional empirical models based on VIs. This study represents a first attempt to couple nitrogen allocation theory with remote sensing data to improve the spectroscopic estimation of LNCA and LNCM.

5 Effect of Species and Maturity on Winter Hardy Small Grain Silage Yield and Quality

Abstract Winter-hardy small grains offer an opportunity to improve soil health as a cover crop, and they can also be used as a forage source for cattle. Winter-hardy small grains differ in the time needed to reach various maturity stages. Species selection may also impact yield and nutritive value. A two-year study was conducted in eastern Nebraska to determine the effect of species and maturity on yield and nutritive value of winter-hardy small grains used for silage. Three species were evaluated; cereal rye, winter wheat, and winter triticale at four stages of maturity: boot, anthesis, milk, and soft dough. The experimental design was a randomized complete block design with four blocks per year. Small grain species were considered whole plots with maturity at harvest considered sub-plot. Each year, the small grain species were randomly assigned within each block. Within each plot, maturity was randomly assigned to one quarter of each plot. Dry matter (DM) forage yield, crude protein (CP), digestible organic matter (DOM), and nutrient yield per hectare were measured and analyzed using the mixed procedure of SAS. Forage yield increased for all species (P &amp;lt; 0.01) with maturity, except for wheat, where there was a decrease at soft dough. Forage yield of cereal rye and triticale did not differ (P&amp;gt;0.05), except at soft dough where triticale was greater (P &amp;lt; 0.01) than cereal rye. Forage yield of triticale and cereal rye yield was greater (P£0.05) than wheat at anthesis and soft dough. Crude protein (% DM) decreased (P &amp;lt; 0.01) with maturity across all species. Among species, CP for cereal rye was greater (P£0.01) than triticale at boot, anthesis, and soft dough, but not different (P³0.10) from wheat at boot, milk, and soft dough. At boot, anthesis, and milk stages, CP of triticale was not different (P³0.07) than wheat, but triticale was lower than wheat (P &amp;lt; 0.01) at soft dough. The DOM (% DM) decreased (P &amp;lt; 0.01) with maturity, except at soft dough. The DOM of cereal rye and wheat did not differ (P &amp;gt; 0.05), but both were greater (P &amp;lt; 0.01) than triticale. Cereal rye and triticale had greater (P £ 0.05) nutrient yields than wheat in terms of energy (DOM) and CP. There was no difference for CP yield across stages (P = 0.10), but there was an effect of maturity on DOM yield. The DOM yield increased from boot to anthesis, (P = 0.05), anthesis and milk did not differ (P = 0.08) and increased (P &amp;lt; 0.01) again at soft dough. This suggests that planting either cereal rye or triticale resulted in the greatest nutrient yield per acre. Harvest at anthesis had increased yield compared to boot with minimal loss in nutritive value; for maximizing energy yield per acre, harvesting at soft dough was the best option.

The Influence of Flag Leaf Removal and Its Characteristics on Main Yield Components and Yield Quality Indices on Wheat

The flag leaf can be an important vehicle for high grain yield due to its position and photosynthetic characteristics. To identify the most adaptive and stable yielding genotype, three winter wheat genotypes were studied during two experimental years under field conditions to quantify the influence of flag leaf removal in different phenological stages on the grain yield and grain quality. To quantify the influence of the flag leaf on the main yield components, the flag leaf was removed every 7 days, starting from the booting stage to ripening. Chlorophyll a, chlorophyll b, and carotenoids were determined from the removed leaves. As a complex trait, the number of grains/spikes and the weight of the grains/spikes were highly influenced by the flag leaf removal during the early generative stages, causing a yield loss from 9% to more than 40%, depending on the variety. It was established that the photosynthetic pigments were highly influenced by the plant phenology stages and the environmental conditions, especially carotenoids, which act as photoprotective and antioxidant agents under stress conditions. Regarding grain quality, flag leaf removal had a significant influence on the accumulation of grain protein and the wet gluten content, the variability of these quantitative traits being also influenced by the climatic conditions.

Water production function and optimal irrigation schedule for rice (Oryzasativa L.) cultivation with drip irrigation under plastic film-mulched

This study determined the Water Production Function (WPF) and Optimal Irrigation Schedule (OIS) for rice (Oryzasativa L.) cultivated with drip irrigation under plastic film. Six different field capacity levels were established, 100% (W1), 90% (W2), 80% (W3), 70% (W4) and 60% (W5). The results showed that, the rice growth and yields and quality were significantly affected by the different irrigation treatments. The rice height and yield decreased from W1to W4, the W2 is the highest yield. The lower the amount of irrigation water applied was, the higher the Irrigation Water Use Efficiency values were. A WPF model was established for this cropping system, and the water sensitivity indices calculated by the mathematical model showed that the crop water sensitivity decreased in the order booting stage > flowering stage > tillering stage > filling stage. Based on this result, the OIS determined by the dynamic solution of several models was as follows: the optimal irrigation levels were 750 m3 ha−1 in the tillering stage, 2125 m3 ha−1 in the jointing-booting stage, 1050 m3 ha−1 in the heading-flowering stage and 325 m3 ha−1 in the milk stage. The WPF and OIS developed in this study provide a theoretical basis for the implementation of rice cultivation with drip irrigation under plastic film in arid regions of China.

Selenium Agronomic Biofortification of Durum Wheat Fertilized with Organic Products: Se Content and Speciation in Grain

The biofortification of cereals is a potential solution for increasing Se levels in the human diet. Here we evaluated whether applying selenate and organic N and S sources via foliar alters Se content and species in durum wheat grain. Field trials were conducted in a Mediterranean environment in 2017–2018 and 2018–2019 on old (Cappelli and old Saragolla) and modern (Marco Aurelio and Nadif) durum wheat varieties. Four organic fertilization strategies were evaluated: the control (dry blood meal at sowing), the application of foliar S (Bio-sulphur at flag leaf) and N (liquid blood meal at the beginning of heading), and their combined use in interaction with a foliar application of selenate at the booting stage. The Se content in grain was determined using ICP-MS and its speciation throughout HPLC-ICP-MS and HPLC-ESI-MS/MS. In 2018, the lower rainfall in the ten days before the Se foliar application caused a higher Se accumulation in the grain (1.63 vs. 1.44 mg kg−1 in 2017–2018 and 2018–2019, respectively). A negative effect of organic foliar S on Se content in grain was observed (−24% with respect to the control). The modern Nadif showed the highest Se content (1.87 mg kg−1), followed by the old variety Cappelli (1.57 mg kg−1). Finally, the Se speciation analysis showed the presence of SeMet and SeMetSeCys. The organic fertilization affected only SeMet, with lower values under organic S fertilization and higher values under organic N fertilization.

Booting stage is the key timing for split nitrogen application in improving grain yield and quality of wheat – A global meta-analysis

Wheat is one of the most important staple crops and is mainly consumed as baked goods. Late nitrogen (N) application following a previous basic fertilization is commonly conducted to increase grain protein concentration and to improve the bread-making quality of wheat. However, the effect of late N application on the yield and quality of wheat highly varied among studies and, therefore, was questioned recently. This global meta-analysis, based on reported field experiments, aimed to clarify whether, and if so under what conditions, a late N (split from the overall N fertilization rate) application that follows an earlier N application is effective in high-protein bread-wheat production. The results showed that split N application enhanced the grain protein concentration by 5.8 %, wet gluten content by 7.9 %, and dough stability time by 10.8 %, while it decreased the grain yield of wheat by 3.5 % compared to that without split N application. However, the results varied, depending on the N application methods and environmental factors. At the fertilization level of 151–200 kg N/ha which is generally recognized as the rational N recommendation rate, split N application could increase the grain protein concentration by 6.9 %, stability time by 14.0 % and wet gluten content by 7.7 % without reducing the grain yield of wheat. More importantly, both the grain yield and quality of wheat were enhanced by split N application only when late N was applied at the booting stage. Moreover, the widely observed negative correlation between grain yield and grain protein concentration was weakened by split N application at the booting stage.

Transcriptome analysis and mining of genes related to shade tolerance in foxtail millet (Setaria italica (L.) P. Beauv.).

A stereo interplanting system with foxtail millet beneath chestnut trees is an effective planting method to raise the utilization of land in chestnut orchards, increase yields and improve quality of chestnut nuts. Consequently, exploration of genes involved in shade tolerance response in foxtail millet and breeding shade-tolerant varieties have become urgent issues. In this study, RNA-seq of leaf samples from two shade-tolerant varieties and three shade-intolerant varieties of foxtail millet at the booting stage was performed. Comparisons between the varieties revealed that 70 genes were commonly differentially expressed. Moreover, the ratio of net photosynthetic rate under shaded environment to that under light environment could be used as an indicator of shade tolerance. Subsequently, weighted gene co-expression network analysis was employed to construct a co-expression network and modules were correlated with this ratio. A total of 375 genes were identified as potentially relevant to shade tolerance, among which nine genes were also present in the 70 differentially expressed genes, which implied that they were good candidates for genes involved in shade tolerance. Our results provide valuable resources for elucidation of the molecular mechanisms underlying shade tolerance and will contribute to breeding of shade-tolerant foxtail millet that are adapted to the shaded environment under chestnut trees.

Simulating the effects of low-temperature stress on wheat biomass growth and yield

Low-temperature stress in late spring poses a serious threat to winter wheat production. In three-year environment-controlled phytotron experiments at both elongation and booting stages, we observed that short-term low-temperature stress decreased leaf area and stem, limited leaf photosynthetic system, and severely reduced grain yield, especially in the low-temperature sensitive cultivar. To better quantify the effects of low-temperature stress on leaf photosynthesis rate (Pn), leaf area index (LAI), biomass partitioning, and grain yield, the lethal temperature at 50% mortality (LT50), low-temperature damage index (LDI), and process-based algorithms were proposed and incorporated into the WheatGrow model. The algorithms take into account the effects of low-temperature with different durations and reflected a low-temperature sensitivity of cultivars at different growth periods by using LT50. The improved WheatGrow model could reproduce well the observed dynamics of the decrease of Pn during the treatment period, recovery of Pn after cold treatments, and the damage to LAI and biomass accumulation under the low-temperature stress treatments. Compared to the original model, RMSE of Pn, LAI, total aboveground biomass, and grain yield in the improved WheatGrow model were reduced by 63 to 77% under low-temperature stress. Although the newly developed algorithms expand crop modeling capacity into quantifying the impacts of low-temperature stress on wheat productivity, further assessments with observed data under field conditions are still required, especially for obtaining suitable parameters at the regional scale.

Reducing and Delaying Nitrogen Recommended by Leaf Critical SPAD Value Was More Suitable for Nitrogen Utilization of Spring Wheat under a New Type of Drip-Irrigated System

Timely and accurate judgment of the nitrogen nutritional status of crops is the key to develop an optimal nitrogen application strategy. However, the evaluation criteria of nitrogen nutrition and nitrogen application strategies at each growth stage of wheat are not clear for the new type of drip-irrigated spring wheat system, TR6S (where one drip tube serves six rows of wheat, with a row spacing (RS) of 10 cm, inter-block space (IBS) of 25 cm and the lateral spacing (LS) of 80 cm, which achieved a lower drip-tube input and higher profit compared with the traditional planting system in Xinjiang). Therefore, we studied the recommendation mechanism of nitrogen fertilizer in different growth stages of wheat based on the critical SPAD values of leaves under TR6S. We set four nitrogen treatments (N1 (300 kg ha−1), N2 (270 kg ha−1), N3 (240 kg ha−1) and N4 (0 kg ha−1)) during two spring wheat growth seasons. The results revealed that the correlation coefficient (r2) between SPAD (soil plant analysis development) value and plant nitrogen content in the middle of first top leaf (L1-M) of wheat was higher than that in other leaf types and leaf positions under TR6S. A quadratic function relationship existed between a SPAD value of L1-M and grain yield. The critical SPAD values at the jointing, booting, anthesis, early milk, and late milk stages were 37.34, 39.40, 42.25, 45.57, and 35.91, respectively. In addition, through the establishment of the nitrogen application recommendation model for various wheat growth stages based on the critical SPAD value, the recommended optimal nitrogen application rates at jointing, booting, anthesis, early milk, and late milk stages were observed to be 69.4, 80.0, 90.8, 44.0, and 6.0 kg ha−1, respectively. This recommended nitrogen application strategy exhibited a better parallel relationship with the nitrogen nutrition index (NNI) of each growth period than the conventional nitrogen application strategy. Therefore, it was more in line with the actual absorption and utilization of nitrogen in wheat of TR6S. In conclusion, the SPAD values of L1-M could be relatively more accurate to evaluate the nitrogen nutrition status of wheat. Compared to traditional nitrogen application strategy, reducing and delaying nitrogen application, recommended based on the leaf SPAD model, was more suitable for nitrogen utilization under TR6S. The results can be applied in other arid and semiarid regions.

Early or late? The role of genotype phenology in determining wheat response to drought under future high atmospheric CO2 levels.

The combination of a future rise in atmospheric carbon dioxide concentration ([CO2 ]) and drought will significantly impact wheat production and quality. Genotype phenology is likely to play an essential role in such an effect. Yet, its response to elevated [CO2 ] and drought has not been studied before. Here we conducted a temperature-controlled glasshouse [CO2 ] enrichment experiment in which two wheat cultivars with differing maturity timings and life cycle lengths were grown under ambient (aCO2 approximately 400 μmol mol-1 ) and elevated (eCO2 approximately 550 μmol mol-1 ) [CO2 ]. The two cultivars, bred under dry and warm Mediterranean conditions, were well-watered or exposed to drought at 40% pot holding capacity. We aimed to explore water × [CO2 ] × genotype interaction in terms of phenology, physiology, and agronomic trait response. Our results show that eCO2 had a significant effect on plants grown under drought. eCO2 boosted the booting stage of the late-maturing genotype (cv. Ruta), thereby prolonging its booting-to-anthesis period byapproximately 3 days (p < 0.05) while unaffecting the phenological timing of the early-maturing genotype (cv. Zahir). The prolonged period resulted in a much higher carbon assimilation rate, particularly during pre-anthesis (+87% for Ruta vs. +22% for Zahir under eCO2 ). Surprisingly, there was no eCO2 effect on transpiration rate and grain protein content in both cultivars and under both water conditions. The higher photosynthesis (and transpiration efficiency) of Ruta was not translated into higher aboveground biomass or grain yield, whereas both cultivars showed a similar increase of approximately 20% in these two traits at eCO2 under drought. Overall, Zahir, the cultivar that responded the least to eCO2, had a more efficient source-to-sink balance with a lower sink limitation than Ruta. The complex water × [CO2 ] × genotype interaction found in this study implies that future projections should account for multifactor interactive effects in modeling wheat response to future climate.

Wheat Curl Mite: A New Source of the Eriophyoid Mite in Wheat Fields Identified

Wheat curl mites (WCMs; Aceria tosichella) are an important global pest of cultivated wheat. Their feeding activities on epidermal cells of wheat leaves result in characteristic leaf curl symptoms that prevent the unfurling of affected leaves and impair the proper emergence of heads from the boot stage. The most significant economic impact of WCM infestation, however, is their ability to vector and transmit four important viruses of wheat, specifically, wheat streak mosaic virus, Triticum mosaic virus, High Plains wheat mosaic emaravirus, and brome streak mosaic virus. Being wingless, WCMs are almost completely dependent on air currents for their dispersal. In addition, because of their obligate lifestyle, wheat field infestations are thought to originate from sources such as volunteer wheat. Corn and other cultivated and noncultivated Poaceae hosts are also known to act as green bridges between successive wheat crops. Consequently, management practices mostly target these off-season host plants but also the use of resistant varieties and other cultural control methods. Here we report the discovery of seed-borne WCM eggs, a previously unknown method of their dispersal, as a possible source of new infestations in wheat fields. This discovery expands our understanding of the biology of WCMs, with potential implications for the development of more holistic and effective management strategies for this economic pest and virus vector. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

WINTER TRITICALE OF BELARUSIAN AND RUSSIAN SELECTION FOR GREEN FODDER DURING THE BOOTING STAGE

The main reserve for increasing the production of fodder and its quality is the expansion of the assortment of fodder crops, the introduction of new promising species and varieties. One way to solve these problems could be the widespread introduction&#x0D; into production of winter triticale as a potential source of fodder. Therefore, the purpose of the scientific work was to study the yield, biometric features of plant development and nutritive value of green mass of winter triticale of Belarusian and Russian&#x0D; selection during the booting stage. As a result of research, winter triticale varieties of the Belarusian selection Slavko, Zveno, Kovcheg and variety sample 1/17 of the Russian selection with high foliage and yield of green mass were revealed. It has been&#x0D; established that winter triticale for green fodder has a longer and wider lamina, higher foliage of plants compared to diploid and tetraploid rye, as well as surpasses in the content of crude and digestible protein and crude fat in terms of the chemical composition of green mass in 1 kg of feed. All the studied varieties and variety samples of winter triticale of Belarusian and Russian selection can be used in the selection process and for green fodder from the beginning of the booting stage.

Changes in Soil Properties, Bacterial Communities and Wheat Roots Responding to Subsoiling in South Loess Plateau of China

This study was carried out to investigate effects of subsoiling on the diversity and composition of the bacterial community in a wheat–maize rotation field in the Guanzhong area of Shaanxi Province, China. After the wheat harvest, surface soil samples were collected under two tillage methods (single rotary tillage (RT) and subsoiling + rotary tillage (ST)) to perform high-throughput sequencing and bioinformatics analysis. Soil properties and root length density (RLD) of winter wheat at booting and flowering stages were also studied. Results showed that ST treatment significantly raised the water storage, organic carbon and total nitrogen contents of deep soil (&gt;40 cm), and notably increased the total soil pH, ammonium nitrogen content and RLD in the tillage layer from 0–70 cm at booting stage and 0~100 cm at flowering stage, but the residual nitrate nitrogen significantly decreased by 17.74%. Compared with RT, soil bacterial richness and diversity in the 10~20 cm layer of ST treatment showed a significantly decreased trend. The relative abundances of GAL15, Actinobacteria, Nitrospirae, Rhizobiales, Burkholderiales, Pseudomonas and Serratia in the 10–20 cm layer were remarkably increased in ST. Principal Component Analysis (PCA) and Redundancy Analysis (RDA) results showed that surface soil pH, ammonium nitrogen and nitrate nitrogen contents have the strongest effect on the bacterial structure. In addition, there were positive correlations between the RLD and the relative abundances of Rhizobiales, Burkholderiales, Pseudomonas and the ammonium nitrogen content. In conclusion, although subsoiling was not conducive to improving soil bacterial community richness and diversity, it significantly increased soil beneficial bacteria (biological nitrogen-fixing bacteria, ammonifying bacteria, nitrobacteria) abundances, reduced the nitrogen loss caused by denitrifying bacteria, promoted earlier root development and improved the plant utilization ratio of soil nutrients.

Response of Rice with Overlapping Growth Stages to Water Stress by Assimilates Accumulation and Transport and Starch Synthesis of Superior and Inferior Grains.

Drought stress at jointing–booting directly affects plant growth and productivity in rice. Limited by natural factors, the jointing and booting stages of short-growth-period rice varieties are highly overlapped in high-latitude areas, which are more sensitive to water deficit. However, little is known about the dry matter translocation in rice and the strategies of starch synthesis and filling of superior and inferior grains under different drought stress was unclear. In this study, the rice plants were subjected to three degrees of drought stress (−10 kPa, −25 kPa, −40 kPa) for 15 days during the jointing–booting stage; we investigated dry matter accumulation and translocation, grain filling and enzyme activities to starch synthesis of superior and inferior grains in rice with overlapping growth stages from 2016 to 2017. The results showed that drought stress significantly reduced dry matter accumulation in the stems and leaves. Mild and moderate drought increased dry matter translocation efficiency. However, severe drought stress largely limited the dry matter accumulation and translocation. A large amount of dry matter remains in vegetative organs under severe drought stress. The high content in NSC in stem and sheath plays a key role in resisting drought stress. The drought stress at jointing–booting directly caused a change in the grain filling strategy. Under moderate and severe drought, the grain-filling active period of the superior grains was shortened to complete the necessary reproductive growth. The grain-filling active period of the inferior grains was significantly prolonged to avoid a decrease in grain yield. The significant decrease in the grain-filling rate of the superior and inferior grains caused a reduction in the thousand-grain weight. In particular, the influence of the grain-filling rate of inferior grains on the thousand-grain weight was more significant. Drought stress changed the starch synthesis strategies of the superior and inferior grains. Soluble starch synthase and starch branching enzyme activities of inferior grains increased significantly under drought stress. GBSS activity was not sensitive to drought stress. Therefore, amylose content was decreased and amylopectin synthesis was enhanced under drought stress, especially in inferior grains.

189 Effects of hay Maturity on the Enteric Methane Emission, Intake, and Energy Metabolism by Beef Heifers

Abstract Heifers (n=12; initial BW=296 ± 30 kg) were used to determine the effect of wheat (Triticum aestinum L.) hay maturity (HM) on energetics and gas emissions. Hay was harvested at 3 maturities and was fed for three 7-d periods. Heifers were randomly assigned to 1 of 3 HM levels including immature (cut at stem elongation, Zadok score [Tottman, 1987] = 3.1, 37% NDF), intermediate (cut at boot stage, Zadok = 3.9-4.1, 55% NDF), and mature (hay cut at milk stage Zadok = 7.9, 63% NDF). Hay was fed for ad libitum intake plus a daily supplement of 0.90 kg of pellets (12% CP) were offered via an automated head-chamber system that measured heifer CO2, CH4, and O2 fluxes. The experiment was designed as a split-plot with HM as the main plot, period the subplot, and beginning body weight as a covariate; main effects were compared using linear and quadratic contrasts. DMI was different for each level of HM with the most DMI for immature and the least for mature, but across all HM levels, DMI did not differ among periods (P ≥ 0.13). Neither HM nor period had an effect (P ≥ 0.16) on total enteric CH4 emissions. However, CO2 emission and O2 consumption had a positive quadratic response to both HM (P ≤ 0.02) and period (P ≤ 0.03). Heat production (HP) had a positive linear effect (P &amp;lt; 0.01) to HM and negative quadratic response to period (P &amp;lt; 0.01). Hay maturity and period had a significant negative linear effect (HM, P &amp;lt; 0.01) and quadratic (period, P &amp;lt; 0.01) effect on metabolizable energy (ME) intake (ME = HP + retained energy). These results indicate that as HM decreased it has a negative effect on DMI, CO2 emissions, O2 consumption, HP, and MEI, but did not have an effect (P ≥ 0.16) on total enteric CH4 emission.

Improving yield and quality of rice under acid rain stress by regulating nitrogen assimilation with exogenous Ca2.

Acid rain threatens crop yield and nutritional quality, and Ca2+ can regulate plant responses to abiotic stresses. To improve the yield and nutritional quality of crops under acid rain stress, we applied exogenous Ca2+ to regulate nitrogen assimilation in rice seedlings under simulated acid rain stress (pH 4.5 or 3.0), taking yield and nutritional quality of rice as evaluation criteria. We found that Ca2+ (5mM) maintained the total nitrogen content of rice at the seedling and booting stages to alleviate the inhibitory effect of simulated acid rain on rice yield. Meanwhile, Ca2+ improved the activity of glutamate synthase to eliminate the disruption of glutamine synthetase/glutamate synthase balance under simulated acid rain. It decreased the efficiency of nitrogen assimilation, thereby reducing the inhibition of essential amino acid content in rice. The mitigation effect on simulated acid rain at pH 4.5 was better than that of simulated acid rain at pH 3.0. Overall, Ca2+ may reduce the negative effect of acid rain on the yield and nutritional quality of crops.

Remotely Sensed Prediction of Rice Yield at Different Growth Durations Using UAV Multispectral Imagery

A precise forecast of rice yields at the plot scale is essential for both food security and precision agriculture. In this work, we developed a novel technique to integrate UAV-based vegetation indices (VIs) with brightness, greenness, and moisture information obtained via tasseled cap transformation (TCT) to improve the precision of rice-yield estimates and eliminate saturation. Eight nitrogen gradients of rice were cultivated to acquire measurements on the ground, as well as six-band UAV images during the booting and heading periods. Several plot-level VIs were then computed based on the canopy reflectance derived from the UAV images. Meanwhile, the TCT-based retrieval of the plot brightness (B), greenness (G), and a third component (T) indicating the state of the rice growing and environmental information, was performed. The findings indicate that ground measurements are solely applicable to estimating rice yields at the booting stage. Furthermore, the VIs in conjunction with the TCT parameters exhibited a greater ability to predict the rice yields than the VIs alone. The final simulation models showed the highest accuracy at the booting stage, but with varying degrees of saturation. The yield-prediction models at the heading stage satisfied the requirement of high precision, without any obvious saturation phenomenon. The product of the VIs and the difference between the T and G (T − G) and the quotient of the T and B (T/B) was the optimum parameter for predicting the rice yield at the heading stage, with an estimation error below 7%. This study offers a guide and reference for rice-yield estimation and precision agriculture.