Modulation of 2-Acetyl-1-pyrroline (2-AP) Accumulation,Yield Formation and Antioxidant Attributes in Fragrant Rice by Exogenous Methylglyoxal (MG) Application

Pot experiments were conducted to investigate the physiological and biochemical effect of exogenous MG application on two fragrant rice cultivars, Meixiangzhan and Yuxiangyouzhan. The MG application included four treatments: 1 mmol·L^–1 (MG1), 5 mmol·L^–1 (MG5), and 10 mmol·L^–1 (MG10), and deionized water as control (MG0). Results indicated that MG1 significantly increased the yield by 11.54–14.06% through promoting the seed-setting rate. Increases on grain 2-acetyl-1-pyrroline (2-AP) content at maturity were found in MG1. The contents of proline, Δ1-pyrrolin-5-carboxylic acid (P5C), pyrroline, and MG, and the activities of proline dehydrogenase (PDH), ornithine aminotransferase (OAT), and Δ1-pyrrolin-5-carboxylate synthase (P5CS) in plant tissues at all sampling stage were also increased in MG1 than MG0. In addition, although the malondialdehyde (MDA) content at all sampling stage was increased by MG application, MG1 increased the antioxidant enzyme activities and soluble protein content in all plant tissues and the pigment content in leaves. However, high-level MG (10 mmol·L^–1) application significantly decreased the yield and grain 2-AP content. Overall, this study suggested that exogenous MG application regulated the 2-AP accumulation, yield formation, and antioxidant attributes in fragrant rice, and that MG application at the concentration of 1 mmol·L^–1 increased the 2-AP content.

     

Grain Yield,Quality and 2-Acetyl-1-Pyrroline of Fragrant Rice in Response to Different Planting Seasons in South China

Climate conditions is an important factor affected the fragrant rice growth and development. In order to study the effects of different planting seasons on fragrant rice performance in South China, present study was conducted with three planting seasons (early season (April to July), middle season (June to September) and late season (August to November)) and three fragrant rice cultivars, ‘Basmati-385’, ‘Meixiangzhan-2’ and ‘Xiangyaxiangzhan’. The results showed that the highest grain yield and grain 2-acetyl-1-pyrroline (2-AP, key component of fragrant rice aroma) content were both recorded in late season treatment while the fragrant rice in middle season treatment produced the lowest grain yield, grain filling percentage, 1000-grain weight and gain 2-AP content. The highest contents of precursors (proline, pyrroline-5-carboxylic acid and 1-pyrroline) which related to 2-AP biosynthesis were recorded in late season treatment compared with early season treatment and middle season treatment. The highest activities of enzymes (proline dehydrogenase, pyrroline-5-carboxylic acid synthetase and ornithine transaminase) which involved in 2-AP biosynthesis were also observed in late season treatment. Moreover, the fragrant rice cultivars in late season possessed the lowest chalk rice rate, chalkiness as well as the highest brown rice rate, head rice and protein content. Thus, the optimal season for fragrant rice production in South China is the late season.     

Foliar Application of Brassinolide Induced Regulation of Grain Yield and Quality,Antioxidant Responses and Aroma in Fragrant Rice

Brassinolide (BR) is a new green plant growth regulator. The present field study was conducted on two fragrant rice cultivars (i.e., Meixiangzhan-2 and Xiangyaxiangzhan) to study the effects of foliar application of BR on fragrant rice performance. At the heading stage, BR solutions at 0.05, 0.15, 0.25 and 0.50 mg L-1 were sprayed on fragrant rice at 600 liters per hectare; these treatments were named as BR1, BR2, BR3 and BR4, respectively. The treatment sprayed with distilled water was taken as a control (CK). Compared with CK, the BR2 treatment significantly enhanced the chlorophyll concentration and net photosynthetic rate for Meixiangzhan-2, and Xiangyaxiangzhan. The BR3 and BR4 treatments increased the concentrations of chlorophyll a, chlorophyll b and carotenoid, and also enhanced net photosynthetic rate by 31.91% and 40.43%, respectively. Higher grain yields were recorded in the BR2 treatment than on CK on Meixiangzhan-2, while on Xiangyaxiangzhan, the BR3 and BR4 treatments increased grain yield compared with CK. In relation to CK, higher head rice rates were recorded in the BR2 treatment for Meixiangzhan-2, and in the BR3 and BR4 treatments for Xiangyaxiangzhan. BR treatments (BR2 for Meixiangzhan-2, BR3 and BR4 for Xiangyaxiangzhan) also significantly enhanced the activities of GPX, SOD and CAT by 10.22% to 23.00%, and reduced the malonaldehyde concentration. In addition, we observed that some BR treatments (BR2 for Meixiangzhan-2, BR3 and BR4 for Xiangyaxiangzhan) decreased the grain 2-acetyl-1-pyrroline concentration of fragrant rice.     

Enhancement of Ultrasonic Seed Treatment on Yield,Grain Quality Characters,and 2-Acetyl-1-Pyrroline Biosynthesis in Different Fragrant Rice Genotypes

Fragrant rice is popular for the good grain quality and special aroma. The present study conducted a field experiment to investigate the effects of ultrasonic seed treatment on grain yield, quality characters, physiological properties and aroma biosynthesis of different fragrant rice genotypes. The seeds of three fragrant rice genotypes were exposed to 1 min of ultrasonic vibration and then cultivated in paddy field. The results of present study showed that ultrasonic seed treatment increased grain yield of all fragrant rice genotypes but the responses of yield formation to ultrasonic were varied with different genotypes. Compared with control, ultrasonic seed treatment increased grain 2-acetyl-1-pyrroline (2-AP, the key component of fragrant rice aroma) content by 13.40%–44.88%. Ultrasonic seed treatment also reduced the crude protein contents in grains. The head rice rate, rice length, chalky rice rate, and chalkiness degree were influenced by ultrasonic for one or two fragrant rice genotypes. The activities of peroxidase and superoxide dismutase were also enhanced due to ultrasonic seed treatment. In conclusion, ultrasonic seed treatment increased grain, regulated grain aroma and quality, and improved stress resistance of fragrant rice varieties.     

Sulphur application improves the growth, seed yield and oil quality of canola

Sulphur (S) nutrition is very important for harvesting potential seed and oil yield of rapeseed. This study evaluated response of foliage applied thiourea on the performance of two canola cultivars Shiralee and Dunkeld. Sulphur was applied to soil (40 kg ha^?1) or foliage (500 and 1,000 mg L^?1) at rosette, bud initiation and flowering stages using elemental S or thiourea as source, respectively; no S application was taken as control. Among all the treatments, soil application of S improved the crop growth, yield and oil quality in both cultivars and was followed by foliar application of thiourea at 1,000 mg L^?1 compared with no application. Soil applied S and foliar thiourea (1,000 mg L^?1) delayed the flowering and maturity. Soil and foliar applied S significantly improved leaf area index, crop growth rate, net assimilation rate and chlorophyll contents. Plant height, number of branches, siliqua per plant, seed number per siliqua, 1,000-seed weight, biological and seed yield were also increased by soil applied S and foliage applied thiourea (1,000 mg L^?1). Nonetheless, improvement in harvest index, seed oil, protein and glucosinolate contents was only observed from foliage applied thiourea (1,000 mg L^?1). Response of cv. Shiralee to sulphur application was better than cv. Dunkeld. In conclusion, foliar applied thiourea (1,000 mg L^?1) can have potential to improve growth, yield and oil quality in canola and can be economically viable and attractive alternative source.     

Zinc-biochemical co-fertilization improves rice performance and reduces nutrient surplus under semi-arid environmental conditions

Biofertilizers are a promising approach to substantially improve nutrient recovery and crop production. Moreover, zinc (Zn) deficiency is one of the key abiotic factors limiting global rice production. However, the effect of Zn-biochemical co-fertilization on rice production and nutrients recovery and surplus under semi-arid environmental conditions is not fully obvious. Two years field experiment was conducted to evaluate the effect of Zn-biochemical (nitrogen “N”, phosphorus “P”, and potassium “K”) co-fertilization on yield and yield components, physico-chemical characteristics, and nutrient recovery and surplus as well as farm profitability of four rice (Oryza sativa L.) cultivars treated with two Zn levels (no Zn application, and 600 mg chelated Zn L^?1 as a foliar application) and six fertilization regimes (no fertilizers application, biofertilizers, 25% NPK plus biofertilizers, 50% NPK plus biofertilizers, 75% NPK plus biofertilizers, and 100% NPK). Biofertilizers mixture (cerealin, phosphorine, and potassiomage) were used. The results revealed that chemical constituents, growth attributes, yield, yield components, nutrients uptake (N, P, K, and Zn), and nutrients recovery (N, P, and K) significantly increased due to Zn foliar application. Biofertilizers replacement for 25% of inorganic NPK combined with Zn provides the highest nutrients uptake through increasing N, P, and K recovery by 57–94%, 61–128%, and 45–69%, respectively in the four rice cultivars compared with 100% NPK treatment. This improvement in nutrients uptake and recovery was attributed to decrease nutrients surplus by 64–78%, 46–53%, and 50–59%, respectively. Additionally, Zn-biochemical co-fertilization improves growth attributes, yield, and yield components of rice cultivars through producing more contents of chlorophyll a and b, carotenoids, total carbohydrates, and total amino acids than using 100% NPK alone. All previous characteristics significantly affected by the cultivated rice variety. The net return under the treatment of 75% NPK plus biofertilizers plus Zn foliar application was 21.5–27.5% higher than the treatment of 100% NPK. Therefore, our findings suggest that biofertilizers replacement for 25% of inorganic NPK combined with Zn foliar application supplies a financially attractive choice to substantially enhance nutrient recovery and production of rice, while effectively reducing nutrients loss.     

Plant maintenance and environmental stress. Summarising the effects of contrasting elevation,soil, and latitude on Quercus ilex respiration rates

Aims

Rice (Oryza sativa L.), wheat (Triticum aestivum L.) and common bean (Phaseolus vulgaris L.) are major staple food crops consumed worldwide. Zinc (Zn) deficiency represents a common micronutrient deficiency in human populations, especially in regions of the world where staple food crops are the main source of daily calorie intake. Foliar application of Zn fertilizer has been shown to be effective for enriching food crop grains with Zn to desirable amounts for human nutrition. For promoting adoption of this practice by growers, it is important to know whether foliar Zn fertilizers can be applied along with pesticides to wheat, rice and also common bean grown across different soil and environmental conditions.

Methods

The feasibility of foliar application of zinc sulphate (ZnSO₄.7H₂O) to wheat, rice and common bean in combination with commonly used five fungicides and nine insecticides was investigated under field conditions at the 31 sites-years of seven countries, i.e., China, India, Pakistan, Thailand, Turkey, Brazil and Zambia.

Results

Significant increases in grain yields were observed with foliar Zn/foliar Zn?+?pesticide (5.2–7.7 % of wheat and 1.6–4.2 % of rice) over yields with no Zn treatment. In wheat, as average of all experiments, higher grain Zn concentrations were recorded with foliar Zn alone (41.2 mg kg^?1) and foliar Zn?+?pesticide (38.4 mg kg^?1) as compared to no Zn treatment (28.0 mg kg^?1). Though the magnitude of grain Zn enrichment was lesser in rice than wheat, grain Zn concentrations in brown rice were significantly higher with foliar Zn (24.1 mg kg^?1) and foliar Zn?+?pesticide (23.6 mg kg^?1) than with no Zn (19.1 mg kg^?1). In case of common bean, grain Zn concentration increased from 68 to 78 mg kg^?1 with foliar Zn alone and to 77 mg kg^?1 with foliar Zn applied in combination with pesticides. Thus, grain Zn enrichment with foliar Zn, without or with pesticides, was almost similar in all the tested crops.

Conclusions

The results obtained at the 31 experimental site-years of seven countries revealed that foliar Zn fertilization can be realized in combination with commonly-applied pesticides to contribute Zn biofortification of grains in wheat, rice and common bean. This agronomic approach represents a useful practice for the farmers to alleviate Zn deficiency problem in human populations.

     

Basal and Foliar Treatment using an Organic Fertilizer Amendment Lowers Cadmium Availability in Soil and Cadmium Uptake by Rice on Field Micro-Plot Experiment Planted in Contaminated Acidic Paddy Soil

In the present study, field micro-plot experiments were conducted to investigate the basal and foliar application of a tested organic fertilizer amendment (OFA) for decreasing the risk of Cd accumulating in rice. The results showed that applications of OFA significantly increased rice yields in Cd-polluted soil and reduced the level of Cd in rice plants, especially in rice grain. In addition, three application methods of OFA were investigated (single basal application (B1, B2, and B3), combined basal application (+LM, +D, and +Z), and foliar application (F1, F2)). Treat B, F, +LM, +D were all higher than control on rice yield with 25.03, 28.05, 30.61, 22.50 g pot^?1 on average, respectively. Among which, rice cadmium depress to 0.33 mg kg^?1 in foliar application is considered to be a more efficient and economical method of heavy metal remediation. The mechanism of foliar application to alleviate the accumulation of Cd in brown rice may be related to the probable Cd sequestration in the leaves and straws. And the doses of the foliar application were 2.25–3.75 kg hm^?2, approximately 1.0–2.5% of the basal application amount yet with more effect (0.10 mg kg^?1 more than single basal; 0.23 mg kg^?1 more than combined basal) on Cd reduction.     

Response of two tomato cultivars to field-applied proline under irrigation with saline water: Growth,chlorophyll fluorescence and nutritional aspects

The response of tomato (Solanum lycopersicum L.) to abiotic stress has been widely investigated. Recent physiological studies focus on the use of osmoprotectants to ameliorate stress damage, but experiments at a field level are scarce. Two tomato cultivars were used for an experiment with saline water (6.57 dS m^?1) and subsurface drip irrigation (SDI) in a silty clay soil. Rio Grande is a salinity-tolerant cultivar, while Heinz-2274 is the salt-sensitive cultivar. Exogenous application of proline was done by foliar spray at two concentrations (10 and 20 mg L^?1) during the flowering stage. Control plants were treated with saline water without proline. Proline at the lower concentration (10 mg L^?1) increased dry mass of different plant organs (leaves, stems, and roots) and it improved various chlorophyll a fluorescence parameters compared with controls. Regarding mineral nutrition, K⁺ and P were higher in different organs, while low accumulation of Na⁺ occurred. However, Mg²⁺ was very high in all tissues of Rio Grande at the higher concentration of proline applied. Thus, the foliar spray of proline at 10 mg L^?1 increased the tolerance of both cultivars. The growth of aboveground biomass of Heinz-2274 was enhanced by 63.5%, while Rio Grande improved only by 38.9%.     

Chemical role of α-tocopherol in salt stress mitigation by improvement in morpho-physiological attributes of sunflower (Helianthus annuus L.)

Elevated concentrations of salts in soil and water represent abiotic stresses. It considerably restricts plant productivity. However, the use of alpha-tocopherol (α-toc) as foliar can overcome this problem. It can improve crop productivity grown under salinity stress. Limited literature is documented regarding its optimum foliar application on sunflower. That’s why the need for the time is to optimize α-toc foliar application rates for sunflower cultivated in salt-affected soil. A pot experiment was performed to select a better α-toc foliar application for mitigation of salt stress in different sunflower cultivars FH (572 and 621). There were 2 levels of salts, i.e., control (no salt stress) and sodium chloride (120 mM) and four α-toc foliar application (0, 100, 200, and 300 mg L^?1). Results showed that foliar application of 100 mg/L- α-toc triggered the remarkable increase in fresh shoot weight, fresh root weight, shoot, and root lengths under salinity stress in FH-572 and FH-621 over 0 mg/L- α-toc. Foliar application of 200 mg/L- α-toc was most effective for improvement in chlorophyll a, chlorophyll b, total chlorophyll and carotenoids compared to 0 mg/L- α-toc. Furthermore, an increase in A was noted in FH-572 (17%) and FH-621 (22%) with α-toc (300 mg L^?1) application under saline condition. In conclusion, the 100 and 200 mg/L- α-toc are the best application rates for the improvement in sunflower FH-572 and FH-621 growth, chlorophyll contents and gas exchange attributes. Further investigations are needed to select a better foliar application rate between 100 and 200 mg/L- α-toc at the field level under the different agro-climatic zone and soil types.     

Foliar application of selenium increases fertility and grain yield in bread wheat under contrasting water availability regimes

The study was conducted to assess whether selenium (Se) application modulates fertility to alter grain yield in bread wheat grown under different moisture regimes. Seeds of wheat cultivar Millat-2011 were sown in the plots using a randomized complete block design with three replicates per treatment. After germination, the plants were exposed to six moisture regimes, viz. no irrigation after germination, irrigation at boot stage, irrigations at boot and grain-filling stages, irrigations at crown root, boot and grain-filling stages, irrigations at crown root, boot, heading and grain-filling stages and irrigations at crown root, stem elongation, boot, heading and grain-filling stages. At the heading stage, foliar spray of sodium selenate (0, 2 and 4 mg Se L^?1) was done. Withholding water at early growth stages significantly increased oxidative stress and decreased growth and grain yield. Irrespective of moisture regimes, foliar application of Se (2 mg L^?1) decreased oxidative stress, modulated photosynthetic pigments and fertility and increased grain yield in wheat. The Se-mediated increase in grain yield was attributed to the increase in chlorophyll and ascorbic acid contents and fertility coupled with decrease of oxidative stress under different moisture regimes. The results could be helpful to manage wheat production in the semi-arid environments.     

Improved Tolerance of Teak (Tectona grandis L.f.) Seedlings to Low-Temperature Stress by the Combined Effect of Arbuscular Mycorrhiza and Paclobutrazol

Low-temperature damage is a common problem for tropical and subtropical plants during their early-growth stage. In this study, an experiment with a L₁₈ (2¹?×?3⁷) mixed orthogonal array in a greenhouse was conducted to determine whether arbuscular mycorrhizal fungi (AMF) inoculation and paclobutrazol (PBZ) application through foliar spray would enhance the chilling tolerance of teak seedlings. One-month-old seedlings of clones 8301, 7544, and 7552 from a Myanmar provenance propagated by tissue culture techniques were inoculated with Glomus versiforme and cultivated for 6?months. The foliar surface of both mycorrhizal and nonmycorrhizal treated plants was sprayed with PBZ at concentrations of 0, 50, and 100?mg?l^?1 once a week for 3?weeks prior to exposure to low temperatures of 6, 3, and 0°C for 12?h in an artificial climate chamber, followed by 12?h of recovery at 20°C room temperature. AMF colonization significantly promoted height and RCD growth and dry biomass accumulation of shoot and root. Under low-temperature stress, AM symbiosis increased leaf chlorophyll content by 22.8%, soluble protein content by 19.6%, superoxide dismutase (SOD) activity by 10.6%, and peroxidase (POX) activity by 9.5%, whereas malondialdehyde content was decreased by 14.1%. Both AMF colonization and the foliar spray PBZ at 50 and 100?mg?l^?1 were capable of alleviating the damage caused by low-temperature stress on teak seedlings by increasing the photosynthetic pigments, accumulation of osmotic adjustment compounds, and antioxidant enzyme (SOD and POX) activity, and by decreasing membrane lipid peroxidation. AMF colonization and foliar spraying of PBZ at 50?mg?l^?1 produced a positive interaction and appears to be a good way to enhance chilling tolerance of teak seedlings experiencing stress at 6, 3 and 0°C for 12?h.     

Production of aromatic three-line hybrid rice using novel alleles of BADH2

Aroma is a key grain quality trait that directly influences the market price of rice globally. Loss of function of betaine aldehyde dehydrogenase 2 (OsBADH2) affects the biosynthesis of 2-acetyl-1-pyrroline (2-AP), which is responsible for aroma in fragrant rice. The current study was aimed at creating new alleles of BADH2 using CRISPR/Cas9 gene editing technology under the genetic background of the japonica Ningjing 1 (NJ1) and indica Huang Huazhan (HHZ) varieties. Sensory evaluation and analysis using headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS) showed that the grains of the four homozygous T₁ lines with new alleles of BADH2 (nj1-cr ^BADH2-1, nj1-cr ^BADH2-2, hhz-cr ^BADH2-1 and hhz-cr ^BADH2-2) produced moderate fragrance and had significantly increased 2-AP content compared with wild-types. Moreover, there were no significant differences in the amylose content and gelatinization temperature among the four lines with new alleles of BADH2 to the wild-types. Thereafter, we crossed the HHZ background new alleles of BADH2 with CMS line Taonong 1A (TN1A) to produce a three-line hybrid variety B-Tao-You-Xiangzhan (BTYXZ) with increased grain aroma. The 2-AP content in grains of the improved BTYXZ-1 and BTYXZ-2 reached at 26.16 and 18.74 μg/kg, and the gel consistency of BTYXZ-1 and BTYXZ-2 increased significantly by 9.1% and 6.5%, respectively, compared with the wild-type Tao-You-Xiangzhan (TYXZ). However, the γ-aminobutyric acid (GABA) content in the improved three-line hybrid rice BTYXZ-1 (5.6 mg/100 g) and BTYXZ-2 (10.7 mg/100 g) was significantly lower than that of the TYXZ. These results demonstrated that CRISPR/Cas9 gene editing technology could be successfully utilized in improving aroma in non-fragrant japonica and indica varieties. In addition, the newly developed BADH2 alleles provided important genetic resources for grain aroma improvement in three-line hybrid rice.     

Physiological and agronomical responses of common bean subjected to tryptophol

With the increasing global demand for food, fuel and fibre, the use of plant growth regulators in agriculture has become an agricultural practice aimed to improve physiological and productive responses. Our work aimed to evaluate the effect of tryptophol (Tol), a precursor of auxin, on common bean (Phaseolus vulgaris L.). The experiment was conducted in pots under greenhouse conditions, where we evaluated the Tol effect on bean crop under two different application forms: T_Soil – soil application of Tol (4.10^?4 mg L^?1) and T_Leaf – leaf tryptophol application (4.10^?4 mg L^?1), plus a reference treatment (0 mg L^?1 of Tol). We analysed the variables: shoot fresh and dry matter; root dry matter, area and volume; leaf macro and micronutrients; CO₂ net assimilation rate (A); stomatal conductance (g_S); internal CO₂ concentration (C_I); foliar transpiration (E); photosynthetic pigment content and some crop production attributes. The application of Tol through the foliar pathway proved to be more advantageous because it improved the shoot fresh and dry matter, increased the root volume and area, favoured less foliar transpiration and improved the length of pods, while the application of Tol in soil induced higher nitrogen accumulation in leaves. Our observations allow the characterization of Tol as a bioactive metabolite, suggesting an important potential for use in agricultural systems.     

Growth and Flowering Responses of Sea Marigold to Daminozide,Paclobutrazol, or Uniconazole Applied as Drenches or Sprays

Borrichia frutescens (L.) DC., sea marigold, is a woody perennial shrub native to the Gulf and Atlantic coasts of North America and has potential as a landscape shrub or groundcover. This study assesses application rates of three commercially available plant growth regulators (PGRs) on B. frutescens during container production. In one experiment, plants were drenched with 0, 0.5, 1, 2, or 4 mg active ingredient (a.i.) pot^?1 of uniconazole or 0, 5, 10, 20, or 40 mg a.i. pot^?1 of paclobutrazol, and in a second experiment, plants were sprayed with solutions of either 0, 25, 50, 100, or 200 mg a.i. L^?1 of uniconazole, 0, 50, 100, 200, or 400 mg a.i. L^?1 of paclobutrazol, or 0, 2500, 5000, 10000, or 20000 mg a.i. L^?1 of daminozide. Drench-applied paclobutrazol (40 mg a.i. pot^?1) reduced shoot mass and root mass (52.9 and 48.5 %, respectively). Both paclobutrazol (40 mg a.i. pot^?1) and uniconazole (2 mg a.i. pot^?1) reduced leaf number by as much as 56.7 and 23.8 %, respectively. Height was reduced 54.9 % by paclobutrazol at 40 mg a.i. pot^?1 and 34.9 % by uniconazole at 2 mg a.i. pot^?1. Drench application of paclobutrazol and uniconazole reduced internode extension by 50.1 and 41.4 %, respectively. At the levels tested, daminozide, paclobutrazol, and uniconazole were generally ineffective at controlling growth when applied as a spray. Drench application of paclobutrazol or uniconazole can be used to control height during container production of B. frutescens, whereas spray application rates need to be tested at higher concentrations or multiple applications to achieve desired control.     

The Effects of Selenium on Physiological Traits, Grain Selenium Content and Yield of Winter Wheat at Different Development Stages

The paper evaluated the effects of Se application time and rate on physiological traits, grain Se content, and yield of winter wheat by field experiment. Se application significantly increased grain Se content and yield, and the increased amount treated with 20 and 30 mg Se?L^?1 was the highest. At blooming–filling stage, Se application significantly increased grain Se content, but did not affect yield. Chlorophyll content was increased by Se application, and the increased amount at heading–blooming stage was higher than that in wheat leaves at the other stages. At four development stages, Se treatments (except for 10 mg Se?L^?1 at jointing–heading stage) significantly decreased the rate of superoxide (O₂ ^?) radical production. At heading–blooming (except for 50 mg Se?L^?1) and blooming–filling stages, hydrogen peroxide (H₂O₂) content was significantly decreased by Se treatments. The rate of O₂ ^? production and H₂O₂ content at 20 and 30 mg Se?L^?1 was the lowest. Se treatments (except for 10 mg Se?L^?1 at regreening–jointing and blooming–filling stages) also induced an evident decrease in malondialdehyde content. Proline content induced by Se treatments at jointing–heading and heading–blooming stages was higher than that in wheat leaves at regreening–jointing and blooming–filling stages. At four development stages, Se treatments all significantly increased glutathione peroxidase activity, and the treatments with 20 and 30 mg Se?L^?1 also evidently increased reduced glutathione content. These results suggested that Se application at different development stages increased antioxidant capacity of wheat, reduced oxidant stress to some extent, and the effects of Se treatments was the best if Se concentration ranged between 20 and 30 mg Se?L^?1. In addition, Se application time was more beneficial for Se accumulation and yield in wheat grain at heading–blooming stage.     

外源海藻糖对高温胁迫下穗分化期水稻叶片生理特性及产量的影响

该研究以耐热型水稻品种Nagina22和热敏型水稻品种YR343为供试材料,采用盆栽试验,设置喷施清水+常温处理(NT0)、喷施清水+穗分化期高温胁迫(HT0),以及分别喷施5、10、15、20 mmol·L^-1外源海藻糖+高温胁迫(分别记为HT1、HT2、HT3、HT4)共6个处理,分析外源海藻糖对高温胁迫下穗分化期水稻叶片叶绿素含量、光合气体交换参数、抗氧化酶活性、渗透调节物质含量、活性氧含量等生理特性,以及籽粒产量及其构成因素的影响,为水稻抗热栽培和耐热品种的选育提供理论依据。结果表明:(1)在高温胁迫下水稻穗分化期,2个水稻品种叶片的叶绿素含量、光合气体交换参数及渗透调节物质含量均降低,叶片MDA和H₂O₂含量以及■的产生速率均上升,叶片抗氧化酶活性呈先增后降的趋势,最终显示水稻籽粒产量及其构成因素显著下降。(2)喷施外源海藻糖能显著增加高温胁迫下穗分化期水稻的每穗粒数、千粒重和结实率,从而提高籽粒产量,其中弱势粒千粒重和结实率的增幅高于强势粒,外源海藻糖最适喷施浓度为15 mmol·L^-1...     

Influence of Pak choi plant cultivation on Se distribution,speciation and bioavailability in soil

Background and aims

The combination of plant breeding and agronomic biofortification is the most reasonable approach to minimize zinc (Zn) deficiency-related problems in humans, but also in crop production. However, its efficiency and suitability under Mediterranean conditions and its effects on the grain yield and quality parameters are not well known.

Methods

Field experiments were conducted over two years in south-eastern Portugal, where soils are deficient in Zn. Ten advanced breeding lines and three commercial varieties of bread-making wheat were fertilized with four Zn treatments as following: i) control, ii) soil Zn application, iii) foliar Zn application and iv) both soil and foliar Zn application.

Results

Low rainfall produced 46 % more of grain Zn concentration but about 67 % less of grain yield. Grain Zn concentration varied greatly across treatments and cultivars with INIAV-1, INIAV-6, INIAV-9 and the commercial varieties being the most efficient. There were no significant increases in Zn concentrations due to soil Zn application, but gains higher than 20 mg kg^?1 were obtained both with foliar and soil+foliar Zn applications. Grain yield was not significantly higher in foliar application, but increased to about 10 % in soil, and about 7 % in soil+foliar applications, respectively.

Conclusions

In soils with low Zn availability, the best strategy to improve grain Zn concentrations has been to select the most efficient cultivars for Zn accumulation with the added application of Zn in soil+foliar form.