Enhancement of Yield,Grain Quality Characters, 2-Acetyl-1-Pyrroline Content,and Photosynthesis of Fragrant Rice Cultivars by Foliar Application of Paclobutrazol

Paclobutrazol is a well-known plant growth regulator. However, the application of paclobutrazol in fragrant rice production has not been reported. The present study conducted a field experiment with two cropping seasons and three fragrant rice cultivars to investigate the effects of paclobutrazol application on yield formation, grain quality, 2-acetyl-1-pyrroline (2-AP, key component of fragrant rice aroma) biosynthesis, and photosynthesis of fragrant rice. At the initial heading stage, paclobutrazol solutions at 0 (control), 30, 60, 100, and 120 mg L^?1 were foliar applied to fragrant rice plants, respectively. Compared with control, paclobutrazol treatments significantly (P?<?0.05) increased grain yield and seed-setting rate of fragrant rice cultivars by 6.77–22.82% and 5.09–25.66%, respectively. Increased contents of photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoid) and the improved net photosynthetic rate at the grain-filling stage were observed due to paclobutrazol treatments. The paclobutrazol application increased head rice rate and grain 2-AP content by 3.94–8.94% and 6.47–18.80%, respectively. Lower chalky rice rate and chalkiness were recorded in paclobutrazol treatment than in control. Moreover, foliar application of paclobutrazol increased proline and Δ1-pyrroline contents in fragrant rice by 7.90–32.12% and 13.21–34.90%. Overall, foliar application of paclobutrazol could enhance productivity, improve grain quality, and increase the 2-AP content of fragrant rice, and 100–120 mg L^?1 was considered the suggested concentration of paclobutrazol application in fragrant rice production.

     

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.     

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.     

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.

     

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.     

中药渣蚓粪对玉米生长及土壤肥力特性的影响

采用盆栽试验,研究了中药渣蚓粪对玉米生长及土壤肥力的影响.结果表明: 随着蚓粪施用量的增加,玉米的株高、茎粗、叶面积、叶绿素含量均显著增加;生长60 d收获时,多数蚓粪处理的土壤容重显著降低;蚓粪处理的土壤pH显著高于对照和相应的化肥处理.蚓粪处理的土壤全氮、有机质含量也明显高于化肥处理,且随蚓粪施用量的增加,效果越趋显著.中药渣蚓粪可作为一种高效有机肥,其合理施用有助于改善土壤物理结构,缓解土壤的酸化进程,提高土壤有机质和氮素含量,有效促进作物生长.     

The Allelopathic Effects of Sunflower and Wheat Root Exudates on <i>Sinapis arvensis and Sinapis alba</i>

In this study, we aimed to investigate the allelopathic effects of sunflower and wheat root exudates on the common weeds such as wild mustard and white mustard in our region. The root exudates which were obtained by soaking 8 weeks old sunflower and wheat seedlings (20 or 40 seedlings) in 100 mL of distilled water for 3 days were applied to the leaves of wild mustard and white mustard. In order to compare the allelopathic effect, the recommended dose (1 g.da^-1 ) and twice the recommended dose (2 g.da^-1 ) of Gromstor (Tribenuron-methyl), a herbicide preferred by farmers for the chemical control of these weeds was also applied. The allelopathy was performed for wild mustard and white mustard seedlings by the measurement of different physiological and biochemical parameters, such as chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, proline, total protein amounts and superoxide dismutase enzyme activity. The amounts of total chl and carotenoid in wild mustard leaves decreased in all treatment groups compared to control. The highest decrease in total chl (50.93%) and carotenoid (46.69%) was oberved in the treatment of 40 wheat seedlings. 100 mL^-1 distilled water. In the white mustard leaves, the amount of total chl in all treatment groups except the treatment group of Gromstor 2 g.da^-1 and carotenoid in all treatment groups increased compared to the control. The highest increases again were observed in 40 wheat seedlings. 100 mL^-1 distilled water treatment. The proline amounts in wild mustard and white mustard increased in all treatment groups. The highest increase was observed for the treatment of 20 wheat seedlings. 100 mL^-1 distilled water in wild mustard (459.69%) and 40 sunflower seedlings. 100 mL^-1 distilled water in white mustard plant (104.70%). In superoxide dismutase enzyme activities, treatments decreased activity except treatment of 40 sunflower seedling root exudate in wild mustard, while increased activity outside commercial herbicide treatment in white mustard. The results showed that sunflower and wheat root exudates have allelopathic effects on wild mustard and white mustard weeds. It is thought that the study will be a reference for new studies that will enable the use of plant root exudates as bioherbicides or foliar fertilizers and will contribute to the fight against weeds in organic agriculture.     

Role of Organic Amendments to Mitigate Cd Toxicity and Its Assimilation in <i>Triticum aestivum</i> L.

In soil biota, higher and enduring concentration of heavy metals like cadmium (Cd) is hazardous and associated with great loss in growth, yield, and quality parameters of most of the crop plants. Recently, in-situ applications of eco-friendly stabilizing agents in the form of organic modifications have been utilized to mitigate the adverse effects of Cd-toxicity. This controlled experiment was laid down to appraise the imprints of various applied organic amendments namely poultry manure (PM), farmyard manure (FYM), and sugarcane press mud (PS) to immobilize Cd in polluted soil. Moreover, phytoavailability of Cd in wheat was also accessed under an alkaline environment. Results revealed that the addition of FYM (5–10 ton ha^-1 ) in Cd-contaminated soil significantly increased germination rate, leaf chlorophyll content, plant height, spike length, biological and grain yield amongst all applied organic amendments. Moreover, the addition of FYM (5–10 ton ha^-1 ) also reduced the phytoavailability of Cd by 73–85% in the roots, 57–83% in the shoots, and 81–90% in grains of wheat crop. Thus, it is affirmed that incorporation of FYM (5–10 ton ha^-1 ) performed better to enhance wheat growth and yield by remediating Cd. Thus, the application of FYM (5–10 ton ha^-1 ) reduced the toxicity induced by Cd to plants by declining its uptake and translocation as compared to all other applied organic amendments to immobilize Cd under sandy alkaline polluted soil.     

Effects of Different Potassium (K) Fertilizer Rates on Yield Formation and Lodging of Rice

As one of the most important nutrients for plants, potassium (K) has substantial effects on growth and development of crops. Present study was conducted in three different sites in South China in late season in 2019 with the objective to study the effects of different applied amounts of K fertilizer on yield formation and lodging of rice. Four K fertilizer treatments, K₀: 0 kg potassium oxide (K₂O) ha⁻¹ (control); K₁: 64.20 kg K₂O ha⁻¹ ; K₂: 128.55 kg K₂O ha⁻¹ and K₃ 153.90 kg K₂O ha⁻¹ were applied in the field experiment. The results showed that K₂ and K₃ treatments significantly increased panicle number per unit area, grain number per panicle, seed-setting rate and the grain yield of rice compared with K₀ treatment. Higher net photosynthetic rates were recorded in K₂ and K₃ treatments than K₀ treatment at tillering stage, heading stage and maturity stage. K fertilizer treatments also increased the chlorophyll content and dry matter accumulation by 6.16–23.52% and 21.32–64.59% compared with K₀ treatment, respectively. Moreover, the total N and K accumulation in the aboveground tissues of rice significantly increased under K₂ and K₃ treatments compared with K₀ treatment. Furthermore, compared with K₀ treatment, K fertilizer treatments significantly enhanced the breaking-resistant strength by 40.94–144.24% and reduced the lodging index of rice by 13.14–36.72%.     

NO3-胁迫及恢复对黄瓜幼苗叶片叶绿素荧光参数及ATPase活性的影响

通过水培试验,探讨了不同NO₃^-浓度胁迫及恢复对黄瓜幼苗叶片叶绿素含量、叶绿素荧光参数及ATPase活性的影响.结果表明,胁迫7 d后,高浓度NO₃^-(168 mmol·L^-1)可极显著提高叶绿素a、叶绿素b、总叶绿素和类胡萝卜素含量,极显著提高初始荧光(F_o)、Mg ATPase和Ca-ATPase活性,而PSⅡ原初光能转化效率(F_v/F_m)、PSⅡ潜在活性(F_v/F_o)和PSⅡ光合电子传递量子效率(ΦPSⅡ),却随NO₃^-浓度的增加而降低.恢复7 d后,所有处理叶绿素和类胡萝卜素含量均低于对照;初始荧光基本都恢复至对照水平;PSⅡ原初光能转化效率和PSⅡ光合电子传递量子效率在NO₃^-浓度低于126 mmol·L^-1时,基本恢复至对照水平,而高于这一水平时,仍显著低于对照;PSⅡ潜在活性在NO₃^-浓度为42和126 mmol·L^-1的处理基本达对照水平,其它处理仍极显著低于对照;Mg-ATPase和Ca-ATPase活性均出现先降低后升高的变化趋势.     

棘孢木霉组合应用对杨树生长和光合特性影响

为研制复方棘孢木霉菌肥制剂,在大田条件下将等浓度（5×10³cfu·cm^-3土）不同组合的棘孢木霉（Trichoderma asperellum）分生孢子T1（Ta536+Ta4）、T2（Ta536+Ta4+Ta492）和T3（Ta536+Ta4+Ta492+Ta650）根施山新杨（Populus davidiana×P.alba var. Pyramidalis）组培移栽苗,研究棘孢木霉组合施用对山新杨生长及光合特性的影响。方差分析结果表明,诱导时间和不同处理对苗高、地径、叶绿素含量、叶绿素a/b值、P_n、Cond、C_i和T_r均有显著影响（P<0.05）：处理组的山新杨苗高、地径及干物质量均在不同程度上高于对照组（CK）,作用效果为T3 >T2 >T1 >CK;60d时,T3、T2和T1组杨树苗生物量分别比CK增加17.99%、14.28%和10.54%;15d时叶绿素含量比CK分别提高7.79%,6.91%和4.17%;叶绿素a/b值分别比CK提高7.79%、5.84%和4.73%。此外,处理组净光合速率（P_n）、胞间CO₂浓度（C_i）、气孔导度（Cond）、蒸腾速率（T_r）均高于CK,并且处理组的最大净光合速率、表观量子效率以及光饱和点均高于CK。同时,诱导时间和不同处理的交互作用对检测的多数指标（除P_n和C_i外）均具有显著影响（P<0.05）。说明4个棘孢木霉菌株组合施用具有协同作用,能提高菌株对环境条件的适应性,增强促生长和改善光合的作用效果。并且T3组对山新杨苗的影响最大、作用速度最快。     

Organic Amendments Improve Plant Morpho-Physiology and Antioxidant Metabolism in Mitigating Drought Stress in Bread Wheat (<i>Triticum aestivum</i> L.)

Due to the unpredictable climate change, drought stress is being considered as one of the major threats to crop production. Wheat (Triticum aestivum L. cv. BARI Gom-26) being a dry season crop frequently faces scarcity of water and results in a lower yield. Therefore, this experiment aims to explore the role of different organic amendments (OAs) in mitigating drought stress-induced damage. The pot experiment consisted of different organic amendments viz. compost, vermicompost and poultry manure @0.09 kg m⁻² soil, biochar @2.5% w/w soil and chitosan @1% w/w soil which was imposed on the plants grown under both well-watered and drought conditions. Results showed that drought stress reduced plant height (15%), SPAD value (16%), relative water content (13%), number of spikelet spike⁻¹ (17%), number of grains spike⁻¹ (12%), and 100-grain weight (18%). Organic amendments act as a protectant and reduce drought stress-induced damages by enhancing the morpho-physiological and yield attributes. Vermicompost enhanced SPAD value by 18%, number of spikelets spike⁻¹ by 20%, number of grains spike⁻¹ by 17%, whereas poultry manure increased plant height by 16% under drought condition compared to control plant. Unlike other OAs applied, vermicompost was proved to be capable of reducing the higher lipid peroxidation and proline content raised by drought condition. Drought stress-induced increment of catalase, ascorbate peroxidase and glutathione reductase activities were also efficiently modulated by the organic amendment application. The present study concluded that OAs play significant roles in alleviating drought stressinduced damages by improving the morpho-physiological attributes and among the different types of OAs used vermicompost performed better which in addition ceased the production of reactive oxygen species.     

Efficient Evergreen Plant Regeneration of <i>Cinnamomum japonicum</i> Sieb. through <i>in vitro</i> Organogenesis

Cinnamomum japonicum Sieb. is an excellent roadside tree and medicinal tree species with considerable ornamental and economic value. In this study, we successfully developed a large-scale micropropagation protocol for C. japonicum for the first time. Sterilized shoots were excised and used as explants for shoot induction on several basal media, supplemented with different concentrations of plant growth regulators (PGRs), such as Thidiazuron (TDZ), N⁶ -Benzyladenine (6-benzylaminopurine) (BA), α-naphthaleneacetic acid (NAA) and Gibberellic acid (GA₃). After comparison, the most efficient medium for shoot regeneration was 1/2 Murashige and Skoog (MS) medium containing 0.5 mg L^–1 BA, 0.05 mg L^–1 NAA and 0.2 mg L^–1 GA₃, which resulted in an average number of induced shoots per explant and shoot length of 5.2 and 1.62 cm at 28 d, respectively. Then, elongated adventitious shoots were transferred to induce roots. 86.7% of shoots was able to root on 1/2 MS medium supplemented with 0.5 mg L^–1 NAA and 0.1 mg L^–1 BA. The earliest rooting time observed was after 21 d and the average root length was up to 3.3 cm after 28 d. Our study shows that C. japonicum can be successfully regenerated through de novo organogenesis, which lays a foundation for future transformation research on this tree.     

甘蓝型油菜苗期生长阶段对NaCl胁迫的生理响应

以甘蓝型油菜自交系2205(强耐盐型)、487(中耐盐型)和1423(敏盐型)为材料,采用土培+水培方法于五叶期研究了0(无盐胁迫,CK)、60 mmol·L-1(低盐)、120 mmol·L-1(中低盐)、180 mmol·L-1(中盐)、240mmol·L-1(高盐)NaCl胁迫后的叶片MDA、可溶性糖、甜菜碱和叶绿素含量的变化特征,为油菜耐盐性评价提供理论依据。结果显示:(1)叶片MDA含量在低盐和中低盐胁迫下降低且显著低于CK,在中盐和高盐胁迫下显著升高,并以品系2205含量最低且升幅最小,品系1423最高且升幅最大。(2)叶片可溶性糖含量在低盐和中低盐胁迫下减少(但2205在中低盐胁迫下显著高于CK),在中盐和高盐胁迫下升高且显著高于CK,并以品系2205含量最高增幅最大且显著高于品系487和1423,品系1423含量最低且增幅最小。(3)叶片甜菜碱含量随NaCl浓度升高增加,品系2205和487在中低以上盐浓度胁迫下显著升高,品系1423仅在高盐胁迫下显著升高,并以品系2205含量最高且增幅最大,1423含量最低且增幅最小。(4)叶片叶绿素含量在低盐和中低盐胁迫下显著增加,且以2205叶片叶绿素含量最高且增幅最大,但在中盐和高盐胁迫下显著减少,并以品系1423含量最低且降幅最高。研究表明,120mmol·L-1以下NaCl胁迫对油菜苗期生长可能有促进作用,180mmol·L-1以上NaCl胁迫则有明显抑制作用,且NaCl浓度越高油菜受伤害越重;油菜苗期生长阶段,NaCl胁迫浓度在120~180mmol·L-1时各生理指标发生显著变化,可能是鉴定耐盐性强弱的适宜浓度;综合分析认为,品系2205具有强的耐盐性,品系1423耐盐性最差,这与之前萌芽期和幼苗期鉴定结果一致。     

Effects of different levels of nitrogen fertilization on soil respiration during growing season in winter wheat (Triticum aestivum)

 在目前全球氮沉降不断增加的背景下, 研究农田土壤呼吸对氮沉降的响应有助于理解未来生态系统碳循环对全球变暖的潜在影响。为探讨不同施氮浓度对华东地区冬小麦(Triticum aestivum)生长期土壤呼吸的影响, 该实验设计了对照组(不施加氮肥)和3种浓度施氮处理组(低浓度施氮15 g·m^–2·a^–1, 中等浓度施氮30 g·m^–2·a^–1, 高浓度施氮45 g·m^–2·a^–1)。使用便携式土壤CO₂通量观测仪LI-8100测定不同施氮浓度处理下冬小麦生长期(2013年12月至2014年5月)的土壤呼吸速率, 并探讨土壤呼吸与土壤温度、湿度等环境因素的关系。结果表明: 低、中、高3种浓度施氮处理的土壤呼吸速率平均值分别为5.29、6.17和6.75 μmol·m^–2 ·s^–1, 与对照组(土壤呼吸速率平均值为4.90 μmol·m^–2·s^–1)相比, 分别增加了7.8%、23.6%和37.8%; 地上生物量分别增加39.9%、104.4%和200.2%, 并与冬小麦生长季的总土壤呼吸正相关。5 cm深度土壤的温度与土壤呼吸速率呈指数关系(p < 0.05), 土壤呼吸季节变化的65%–75%由土壤温度引起, 其温度敏感性为2.09–2.32。结果表明, 添加氮肥促进了植物的生长, 增加了生物量, 从而增加了冬小麦农田的土壤呼吸速率。     

Salt Stress Affects the Growth and Yield of Wheat (<i>Triticum aestivum</i> L.) by Altering the Antioxidant Machinery and Expression of Hormones and Stress-Specific Genes

Understanding physiological responses in saline agriculture may facilitate wheat breeding programs. Based on a screening test, the Ningmai-14 (NM-14) and Yangmai-23 (YM-23) wheat cultivars were selected for further experiments to understand the underlying salinity tolerance mechanism. This study investigated the effects of five salinity levels such as Control (CK) = 0 (without NaCl stress), S1 = 0.20%, S2 = 0.25%, S3 = 0.30% and S4 = 0.35% of NaCl concentrations of soil on wheat plants. The results showed that increased salinity concentration reduced the growth and yield of wheat cultivars (NM-14 and YM-23). However, YM-23 (12.7%) yielded more than NM-14 at maximum salinity stress. The higher salinity (S4) increased the concentration of Na⁺ (4.3 to 5.8-fold) and P contents (2.5 to 2.2-fold), while reducing the average concentrations of K⁺, Cu, and K⁺/Na⁺ ratio. The higher salinity (S4) reduced the spikelet length by 21.35% (followed by grain spike⁻¹), and the starch content by 18.81%. In the YM-23 cultivar, higher salinity increased superoxide dismutase (SOD), total antioxidant capacity (TAC), and amylase. Compared to NM-14, induced expression of TaYUC2, 6, and TaGA13ox, 20ox genes were recorded in YM-23. Similarly, in YM-23 the stress-specific genes such as TaHSP70, 90 were enhanced whereas, TaSOS1, 2 were suppressed. Overall, our study revealed that salt tolerant cultivars modulate hormonal and antioxidant activities, thus maintaining high growth.

     

太阳辐射减弱对水稻光合生理特性和中微量元素积累的影响

近年来雾霾等大气环境污染问题突出,气溶胶导致到达地表的太阳辐射强度降低,对农作物生长造成了较大影响。为了探讨太阳辐射强度降低对粮食作物生理特性和矿质元素营养的影响,本研究以‘南粳5055’水稻品种为供试材料,采用田间随机区组设计,通过不同程度遮光处理模拟弱光环境(CK,不遮光对照;Y₁、Y₂遮光率分别为19%、45%),研究了在水稻关键生育期(拔节期、抽穗期、灌浆期)内叶绿素含量(SPAD)、叶面积指数(LAI)、叶片净光合速率、产量和籽粒中、微量金属元素(Ca、Mg、Fe、Zn、Mn、Cu)含量的响应特征。结果表明: 全生育期内遮光处理抑制了水稻光合作用产物的合成,降低了叶面积指数;但在生育前期对叶绿素含量无显著影响,在生育后期则显著增加。两种遮光处理下水稻的千粒重较CK分别降低了14.4%和18.4%,结实率降低了4.3%和12.9%,从而导致水稻产量下降,且随着遮光程度增加,水稻减产率加大,产量分别下降了58.5%和66.4%。遮光处理籽粒糙米和颖壳中金属元素含量升高,尤其微量元素含量显著上升。可见,遮光对水稻生长产生了不利影响,最终使其减产,并使Cu、Mn等重金属元素含量增加,这可能造成污染风险进而对人体健康造成威胁,因此,太阳辐射减弱对作物产量和品质的影响需要综合评价。     

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.     

添加玉米和水稻秸秆对淹水土壤pH、二氧化碳及交换态铵的影响

通过温室土壤培养试验,研究了不同添加量玉米和水稻秸秆对淹水土壤pH、CO₂及交换态铵的影响.结果表明：在接近中性的土壤中加入秸秆可使土壤pH值降低,4 g·kg^-1玉米和水稻秸秆处理的土壤pH值均与对照差异显著（P＜0.05）,而1 g·kg^-1玉米和水稻秸秆处理与对照差异不显著（P＞0.05）.土壤溶液中的CO₂含量随秸秆添加量的增加而增大,1 g·kg^-1玉米和水稻秸秆处理的土壤溶液CO₂含量最大值分别为35.9％和31.9％（v/v）,与对照（25.8％）差异达显著水平（P＜0.05）,但两者间差异不显著（P＞0.05）;4 g·kg^-1玉米和水稻秸秆处理的土壤溶液CO₂含量最大值分别为54.2％和41.8％（v/v）,与对照差异极显著（P＜0.01）,两者间差异也达显著水平（P＜0.05）.在不施氮肥的情况下,添加秸秆可降低土壤铵态氮浓度,且铵态氮浓度随秸秆添加量的增加而降低,不同添加量处理间差异显著（P＜0.05）;在施入氮肥的情况下,1 g·kg^-1玉米和水稻秸秆处理提高了土壤铵态氮浓度,而4 g·kg^-1玉米和水稻秸秆处理降低了土壤铵态氮浓度.无论是否施入氮肥,玉米和水稻秸秆处理的土壤铵态氮浓度差异不显著（P＞0.05）.