Improving the Productivity of Bread Wheat by Good Management Practices under Terminal Drought

Drought‐induced damages in crop plants are ranked at top amid all losses instigated by diverse abiotic stresses. Terminal drought (drought at reproductive phase) has emerged as a severe threat to the productivity of wheat crop. Different seed enhancement techniques, genotypes and distribution of crop plants in different spacings have been explored individually to mitigate these losses; however, their interaction has rarely been tested in improving drought resistance in wheat. This study was conducted to evaluate the potential role of different seed enhancement techniques and row spacings in mitigating the adversities of terminal drought in two wheat cultivars during two consecutive growing seasons of 2010–2011 and 2011–2012. Seeds of wheat cultivars Lasani‐2008 (medium statured) and Triple Dwarf‐1 (dwarf height) soaked in water (hydropriming) or CaCl₂ (osmopriming) were sown in 20‐, 25‐ and 30‐cm spaced rows; just before heading, the soil moisture was maintained at 100 % field capacity (well watered) or 50 % field capacity (terminal drought) till maturity. Terminal drought significantly reduced the yield and related traits compared with well‐watered crop; however, osmopriming improved the crop performance under terminal drought. Among different row spacings, wheat sown in 20‐cm spaced rows performed better during both years of study. Wheat cultivar Lasani‐2008 performed better than cultivar Triple Dwarf‐1 under both well‐watered and stress conditions. Maximum net returns and benefit–cost ratio were recorded from osmoprimed seeds of cultivar Lasani‐2008 sown in 20‐cm spaced rows under well‐watered condition. Nonetheless, osmoprimed seeds of cultivar Lasani‐2008 sown in 20‐cm spaced rows were better able to produce good yield under terminal drought.     

Evaluating the role of seed priming in improving drought tolerance of pigmented and non‐pigmented rice

This study was conducted to evaluate the influence of seed priming on drought tolerance of pigmented and non‐pigmented rice. Seeds of pigmented (cv. Heug Jinju Byeo) and non‐pigmented (cv. Anjoong) rice were soaked in water (hydropriming) or solution of CaCl₂ (osmopriming). Seeds were sown in soil‐filled pots retained at 70 (well‐watered) and 35% (drought) water‐holding capacity. Drought stress caused erratic and poor stand establishment and decreased the growth of both rice types. More decrease in plant height and leaf area under drought stress was noted in pigmented rice, whereas decrease in root length and seedling dry weight, under drought, was more obvious in non‐pigmented rice. Pigmented rice maintained more tissue water and photosynthesis and had more polyphenols, flavonoids and antioxidant activity than non‐pigmented rice. Seed priming was effective in improving stand establishment, growth, polyphenols, flavonoids and antioxidant activity; however, extent of improvement was more in pigmented rice under drought. In conclusion, drought caused erratic germination and suppressed plant growth in both rice types. However, pigmented rice had better drought tolerance owing to uniform emergence, and better physiological and morphological plasticity. Seed priming was quite helpful in improving the performance of both rice types under drought and well‐watered conditions.     

Improving the Performance of Wheat by Seed Priming Under Saline Conditions

Salinity is one of a major threat in harvesting good wheat stand on sustained basis. In this study, potential of seed priming techniques to improve the performance of wheat varieties (SARC‐1 and MH‐97) in a saline field was tested. For priming, wheat seeds were soaked in aerated solution of ascorbate (50 mg l^?1; ascorbate priming), salicylic acid (50 mg l^?1; salicylicate priming), kinetin (50 mg l^?1; kinetin priming) and CaCl₂ (50 mg l^?1; osmopriming) for 12 h. For comparison, seeds were also soaked in simple water (hydropriming); in addition, untreated seeds were also taken as control. Seed priming treatments substantially improved the stand establishment; osmopriming (with CaCl₂) was at the top however. Likewise maximum fertile tillers, grains per spike, 1000‐grain weight, grain yield and harvest index were observed in plants raised from seeds osmoprimed (with CaCl₂) followed by ascorbate priming in both the varieties tested. As an index of salinity tolerance, seed priming treatments also improved the leaf K⁺ contents with simultaneous decrease in Na⁺ concentration, osmopriming being the best treatment. Similarly, maximum total phenolic contents, total soluble proteins (TSP), α‐amylase and protease activities were observed in osmoprimed (with CaCl₂) seeds followed by ascorbate priming. Economic analysis also indicated that osmopriming is more viable with maximum net return and benefit‐to‐cost ratio. In conclusion, different seed priming treatments in wheat seeds improved the salinity tolerance nonetheless osmopriming (with CaCl₂) was the most effective treatments to get higher grain yield and net return in both wheat varieties whereas kinetin was the least effective.     

Morphological,physiological and biochemical aspects of osmopriming-induced drought tolerance in lentil

Lentil (Lens culinaris Medik.) is an important grain legume crop, mostly grown in semi-arid environments and often faces intermittent drought spells during different growth stages, which severely hamper its yield. This study, comprising of three separate experiments, was conducted to evaluate the potential of seed priming with CaCl₂ in improving drought tolerance in lentil. In the first experiment, lentil seeds were hydroprimed (water) or osmoprimed with 0.5 and 1% CaCl₂; while non-primed seeds were taken as control. In the second and third experiments, lentil seeds were subjected to pre-optimized osmopriming (1% CaCl₂) and hydropriming followed by surface drying or re-drying of primed seeds to original weight. The first two experiments were conducted in petri plates, while, in experiment 3, seeds were planted in plastic pots containing peat moss, maintained at 75% water holding capacity (WHC; well-watered) or 50% WHC (water deficit). Hydropriming and osmopriming improved seed germination, seedling growth, biomass production, chlorophyll intensity, sugar accumulation and reduced the oxidative stress in lentil under water deficit. However, osmopriming (1% CaCl₂) was more effective than the hydropriming in improving the lentil growth, biomass production, Ca accumulation and sugar metabolism under both well-watered and water deficit conditions. Seed surface drying, after priming, was more beneficial in improving the lentil performance, under both well-watered and water deficit conditions, than re-drying to original weight. Osmopriming (1% CaCl₂) increased the seeding dry weight (67%), SPAD value (140%), leaf Ca concentration (56%), α-amylase activity (55%), total soluble sugars (48%) and reduced malanodialdehyde content (35.9%) and total antioxidant activity (29.2%) than un-primed seeds under water deficit. In conclusion, osmopriming improved the lentil performance under optimal and water deficit conditions through early and synchronized emergence, better sugar and Ca accumulation which reduced the oxidative damage and resulted in better seedling growth and biomass production.     

Seed priming improves stand establishment and productivity of no till wheat grown after direct seeded aerobic and transplanted flooded rice

No tillage (NT) in wheat (Triticum aestivum L.) offers a pragmatic option for resolving the time and edaphic conflicts in rice (Oryza sativa L.)–wheat cropping system (RWS). However, poor stand establishment is an issue in NT wheat, which adversely affects crop growth, grain yield, and profitability. Therefore, a 2-year field study was conducted to assess the potential role of seed priming in improving the stand establishment, grain yield, water productivity and profitability of NT and plough till (PT) wheat grown after direct seeded aerobic (conservation) and puddled transplanted flooded (conventional) rice-based systems. For seed priming, wheat seeds were soaked in aerated water (hydropriming) or solution of CaCl₂ (ψs −1.25 MPa; osmopriming) for 12 h, and non-primed seeds were used as control. After harvest of rice, grown as direct seeded aerobic and puddled transplanted flooded crop, primed and non-primed wheat seeds were sown following NT and PT. In both years, stand establishment of NT wheat after direct seeded aerobic and puddled transplanted flooded rice was impeded. Nonetheless, seed priming improved the stand establishment which was visible through earliness and better uniformity of seedling emergence. Overall, primed seeds completed 50% emergence in 6.4 days, against 7.8 days taken by non-primed seeds in NT wheat. The highest emergence index (41.7) was recorded in primed seeds versus 32.0 for non-primed seeds. Improved stand establishment enhanced growth, grain yield, water productivity and profitability in NT wheat. In this regard, osmopriming was the most effective, and produced grain yield of 4.5 Mg ha⁻¹ against 3.8 Mg ha⁻¹ for non-primed seeds in NT wheat. Water productivity of the NT wheat grown from osmoprimed seeds was 8.72 kg ha⁻¹ mm⁻¹ while that from non-primed seeds was 7.21 kg ha⁻¹ mm⁻¹. Among the RWSs, the maximum wheat biomass was produced with PT after direct seeded aerobic rice. However, grain yield, water productivity, and profitability were the highest in NT wheat following direct seeded aerobic rice. Wheat yields grown after direct seeded aerobic rice and transplanted flooded rice were 4.4 and 4.2 Mg ha⁻¹ respectively. Planting NT wheat after direct seeded aerobic rice provided the highest system productivity (1.80) than other RWSs. Thus, seed priming is a viable option to improve the stand establishment, grain yield, water productivity and profitability of NT wheat in the RWS. Nonetheless, osmopriming was a better option than hydropriming in this regard.     

种子引发处理对棉花种子发芽的影响

时新疆棉花主栽品种“新陆早10号”种子采用不同的处理方法，调查了各处理种子发芽速度、发芽整齐度、发芽试验及种苗萌发试验。结果表明：6种不同水合时间和水量的处理中，6h的水合时间处理获得了最高的发芽势和发芽率、较好的发芽整齐度和较快的发芽速度，是较为理想的水合处理方法。棉花种子的引发处理能够有效的提高种子活力、加速种苗萌发、提高种子发芽整齐度和发芽率。其中大分子PEG盐渗处理（OP）在加快种子发芽和种苗萌发的速度上显著优于未处理种子，略优于6h水合处理；而水合处理（HP）在提高种子的发芽势、发芽率及最大发芽率方面显著优于OP和未处理种子。但HP和OP处理后种子的畸形苗和染病种苗率显著上升，这与前人的报道结果相一致。有关棉花种子引发处理与种带病原菌的发生间的关系有待进一步研究。     

Response of Wheat and Barley during Germination to Seed Osmopriming at Different Water Potential

Pre-sowing osmotic seed treatments were evaluated as a means of improving water uptake and germination performance of wheat ( Triticum durum L. cv. Hourani-27) and barley ( Hordeum vulgare L. cv. ACSAD 176) under four levels of water potential (0, –0.4, –0.8 and –1.2 MPa) created by using polyethylene glycol 8000. Seeds were osmoprimed in aerated solutions of 0.0, 0.2, 0.4 or 0.6 M KCl at 24 ± 2°C overnight and then rinsed and dried. Rate of water uptake by seeds was higher in osmoprimed than untreated seeds of both crops regardless of the water potential level. Decreasing water potential (more stress) adversely affected rate of water uptake in seeds of both crops. Seeds osmopriming increased germination percentage and decreased time to 50% germination at high water potentials (low stress), whereas the germination at low water potentials (more stress) was not affected by osmopriming treatments. The effect of osmopriming on rate of water uptake, germination percentage, and time to 50% germination was more pronounced in wheat than in barley. Reduction in the lag time of imbibition may be accounted for in part by some germination rate enhancement in the osmopriming treatments. Fresh weight and length of shoots (plumules) and roots (radicles) were enhanced in osmoprimed seeds in comparison to untreated seeds, in both crops at high water potentials (0 and – 0.4 MPa). As water potential in the medium decreased, these traits were inversely affected regardless of osmopriming treatment. Longer roots in wheat compared to barley were noted in the positive osmopriming treatments at high water potentials (0 and – 0.4). These results might indicate that wheat is more responsive than barley at relatively high water potentials to osmopriming through rapid penetrating root system.     

Foliage‐applied sodium nitroprusside and hydrogen peroxide improves resistance against terminal drought in bread wheat

Terminal drought is threatening the wheat productivity worldwide, which is consumed as a staple food by millions across the globe. This study was conducted to examine the influence of foliage‐applied stress signalling molecules hydrogen peroxide (H₂O₂; 50, 100, 150 μm ) and nitric oxide donor sodium nitroprusside (SNP; 50, 100, 150 μm ) on resistance against terminal drought in two bread wheat cultivars Mairaj‐2008 and BARS‐2009. These stress signalling molecules were applied at anthesis stage (BBCH 61); drought was then imposed by maintaining pots at 35% water holding capacity. Terminal drought caused significant reduction in grain yield of both tested bread wheat cultivars; however, foliage application of both stress signalling molecules at either concentration improved the performance of both bread wheat cultivars. Maximum improvement in 100‐grain weight (12.2%), grains per spike (19.7%), water‐use efficiency (WUE; 19.8%), chlorophyll content index (10.7%), total soluble phenolics (21.6%) and free leaf proline (34.3%), and highest reduction in leaf malondialdehyde contents (20.4%) was recorded when H₂O₂ was foliage‐applied at 100 μm . Foliage application of SNP enhanced the grains per spike, 100‐grain weight and grain yield by 14.9%, 11.3% and 20.1%, respectively, than control. The foliage‐applied stress signalling molecules improved the accumulation of soluble phenolics, proline and glycine betaine with simultaneous reduction in malondialdehyde contents, which enabled wheat plants to sustain the biological membranes under stress resulting in better stay green (high chlorophyll contents) under drought. This helped improving the grain number, grain weight, grain yield, WUE and transpiration efficiency. In crux, foliage‐applied H₂O₂ and SNP, at pre‐optimized rate, may be opted to lessen the drought‐induced yield losses in bread wheat in climate change conditions.     

抗旱剂拌种处理对小麦萌发和幼苗生长的影响

干旱胁迫下用抗旱剂Ⅰ号拌种处理小麦种子可以提高小麦出苗率，促进根系发育，增加根冠比。处理后，幼苗的生理生化指标均高于对照，可使幼勒在较低水势下保持正常生长。     

Seed priming improves germination in saline conditions for Chenopodium quinoa and Amaranthus caudatus

Seed priming has proved to be an effective method in imparting stress tolerance to plants using natural and/or synthetic compounds to treat the seeds before germination. The present work aimed to evaluate the effectiveness of priming treatments in seeds of Chenopodium quinoa and Amaranthus caudatus to improve germination under NaCl. Species‐specific protocols for seed hydropriming and osmopriming were established by germinating seeds under different water potentials and creating seed imbibition curves. Primed seeds were then germinated under different concentrations of NaCl, and the effect of priming was analysed based on the parameters, such as final germination percentage (FGP), germination index (GI) and mean germination time (MGT). Seed hydropriming and osmopriming caused significant improvements in germination velocity and uniformity, reflected in high FGP, high GI and reduced MGT under salinity. C. quinoa had a higher tolerance to salinity than A. caudatus during seed germination. Improved germination in salinity resulted from osmopriming seeds with solutions of low water potential for A. caudatus, while for C. quinoa, this effect was achieved from hydropriming and osmopriming seeds with solutions of high water potential. Primed tolerance to moderate salinity was achieved for A. caudatus, and for both species, the salinity threshold for germination to occur was slightly broadened.     

Exogenous application of allelopathic water extracts helps improving tolerance against terminal heat and drought stresses in bread wheat (Triticum aestivum L. Em. Thell.)

The allelopathic water extracts (AWEs) may help improve the tolerance of crop plants against abiotic stresses owing to the presence of the secondary metabolites (i.e., allelochemicals). We conducted four independent experiments to evaluate the influence of exogenous application of AWEs (applied through seed priming or foliage spray) in improving the terminal heat and drought tolerance in bread wheat. In all the experiments, two wheat cultivars, viz. Mairaj‐2008 (drought and heat tolerant) and Faisalabad‐2008 (drought and heat sensitive), were raised in pots. Both wheat cultivars were raised under ambient conditions in the wire house till leaf boot stage (booting) by maintaining the pots at 75% water‐holding capacity (WHC). Then, managed drought and heat stresses were imposed by maintaining the pots at 35% WHC, or shifting the pots inside the glass canopies (at 75% WHC), at booting, anthesis and the grain filling stages. Drought stress reduced the grain yield of wheat by 39%–49%. Foliar application of AWEs improved the grain yield of wheat by 26%–31%, while seed priming with AWEs improved the grain yield by 18%–26%, respectively, than drought stress. Terminal heat stress reduced the grain yield of wheat by 38%. Seed priming with AWEs improved the grain yield by 21%–27%; while foliar application of AWEs improved the grain yield by 25%–29% than the heat stress treatment. In conclusion, the exogenous application of AWEs improved the stay green, accumulation of proline, soluble phenolics and glycine betaine, which helped to stabilize the biological membranes and improved the tolerance against terminal drought and heat stresses.     

Application of natural plant extracts improves the tolerance against combined terminal heat and drought stresses in bread wheat

Drought and heat are among the main abiotic stresses causing severe damage to the cereal productivity when occur at reproductive stages. In this study, ten wheat cultivars were screened for combined heat and drought tolerance imposed at booting, heading, anthesis and post‐anthesis stages, and role of the foliage applied plant extracts was evaluated in improving the performance of differentially responding wheat cultivars under terminal heat and drought stresses. During both years, wheat crop was raised under ambient temperature and 70% water holding capacity (WHC) till leaf boot stage. The plant extracts (3% each) of sorghum, brassica, sunflower and moringa were foliage applied at booting, anthesis and post‐anthesis stage; and after one week of application of these plant extracts, combined heat and drought was imposed at each respective stage. Heat and drought stresses were imposed at each respective stage by placing pots in glass canopies with temperature of 4 ± 2°C above than the ambient temperature in combination with drought stress (35% WHC) until maturity. Combination of drought and heat stresses significantly reduced the performance of tested wheat cultivars; however, stress at the booting and heading stages was more damaging than the anthesis and post‐anthesis stages. Cultivars Mairaj‐2008 and Chakwal‐50 remained green with extended duration for grain filling, resulting in the maintenance of number of grains per spike and 100‐grain weight under stress conditions and thus had better grain yield and water‐use efficiency. However, in cultivars Fsd‐2008, and Shafaq‐2006, the combined imposition of drought and heat accelerated the grain filling rate with decrease in grain filling duration, grain weight and grain yield. Foliar application of all the plant extracts improved the wheat performance under terminal heat and drought stress; however, brassica extract was the most effective. This improvement in grain yield, water‐use efficiency and transpiration efficiency due to foliage applied plant extracts, under terminal heat and drought stress, was owing to better stay‐green character and accumulation of more soluble phenolics, which imparted stress tolerance as indicated by relatively stable grain weight and grain number. In crux, growing of stay‐green wheat cultivars with better grain filling and foliage application of plant extracts may help improving the performance of bread wheat under combined heat and drought stresses.     

败脂酸钙拌种+赤酶酸浸种复合处理对干旱胁迫下小麦生长的效应

干旱胁迫下用败脂酸钙拌种 赤酶酸浸种复合处理小麦种子可以提高出苗率,增加根冠比,幼苗的各项生化指标均高于对照.8h浸种 2%拌种处理的出苗效果最好,出苗率为94%,高于正常水分对照.     

Improving the Drought Tolerance in Rice (Oryza sativa L.) by Exogenous Application of Salicylic Acid

Drought stress encumbers the rice growth predominantly by oxidative damage to biological membranes and disturbed tissue water status. In this study, the role of salicylic acid (SA) to induce drought tolerance in aromatic fine grain rice cultivar Basmati 2000 was evaluated. SA was applied as seed and foliar treatments. For seed treatment, rice seeds were soaked in 50, 100 and 150 mg l⁻¹ aerated solution of SA for 48 h and then dried back. Treated and untreated seeds were sown in plastic pots in a phytotron. At four leaf stage, one set of plants was subjected to drought stress, while the other remained well watered. Drought was maintained at 50 % of field capacity by watering every alternate day. For exogenous application, SA was applied 50, 100 and 150 mg l⁻¹ at five leaf stage. In the control, SA was neither applied exogenously nor as seed treatment. Drought stress severely affected the seedling fresh and dry weight, photosynthesis, stomatal conductance, plant water relations and starch metabolism; however, SA application improved the performance of rice under both normal and stress conditions. Drought tolerance in rice was well associated with the accumulation of compatible solutes, maintenance of tissue water potential and enhanced potency of antioxidant system, which improved the integrity of cellular membranes and facilitated the rice plant to sustain photosynthesis and general metabolism. Foliar treatments were more effective than the seed treatments. Foliar application with 100 mg l⁻¹ (FA 100) was the best treatment to induce the drought tolerance and improve the performance under normal and stress conditions compared with the control or other treatments used in this study.     

Improving resistance against terminal drought in bread wheat by exogenous application of proline and gamma‐aminobutyric acid

Scarcity of water is a severe constraint, which hinders the wheat productivity worldwide. However, foliage application of osmoprotectants may be useful in reducing the drought‐induced yield losses in wheat (Triticum aestivum L.). In this study, potential of foliage applied osmoprotectants (proline, gamma‐aminobutyric acid) in improving the performance of bread wheat against terminal drought was evaluated. Both proline and gamma‐aminobutyric acid (GABA) were foliage applied at 50, 100 and 150 mg/L at anthesis stage (BBCH‐identification code‐ 61), in two bread wheat cultivars viz. Mairaj‐2008 and BARS‐2009. After 1 week of foliage application of these osmoprotectants, drought was imposed by maintaining the pots at 35% water holding capacity. Imposition of drought caused significant reduction in the grain yield of both tested bread wheat cultivars; nonetheless, foliage applied osmoprotectants at either concentration improved the chlorophyll contents, accumulation of proline, glycinebetaine and total soluble phenolics and reduced the malondialdehyde contents, which resulted in better stay green, maintenance of grain weight and grain number under drought stress, thus resulting in better grain yield, water‐use efficiency and transpiration efficiency in both wheat cultivars. However, foliage applied proline at 150 mg/L, and GABA at 100 mg/L was most effective than other concentrations of these osmoprotectants. Performance of cultivar Mairaj‐2008 was quite better than cultivar BARS‐2009. In crux, foliar application of proline and GABA at pre‐optimized rate can be opted as a shotgun approach to improve the performance of wheat under terminal drought.     

抗旱剂对玉米出苗和幼苗生长的影响

用抗旱浸种剂和拌种剂复合处理玉米种子 ,在较低的土壤水分条件下 ,可提高玉米种子的出苗率和出苗速度 ,促进幼苗根系生长。同时能提高叶绿素含量和可溶性糖含量 ,降低游离脯氨酸含量 ,植株保水抗旱力明显增强。试验结果表明 ,出苗率、苗高、苗干重、根长、根干重、根体积、根冠比、叶绿素含量、可溶性糖含量、脯氨酸含量处理间均有显著差异 ,其中用浸种剂浸 8h和用 2 %拌种剂复合处理的效果最好 ,显著优于空白对照和 8h清水浸种处理。     

Chilling Tolerance in Hybrid Maize Induced by Seed Priming with Salicylic Acid

The optimum temperature for maize germination is between 25 and 28 °C. Poor and erratic germination at suboptimal temperature is the most important hindrance in its early sowing. This study was conducted to induce chilling tolerance in hybrid maize (Zea mays L.) by seed priming with salicylic acid (SA) and to unravel the background biochemical basis. For seed priming, maize hybrid (Hycorn 8288) seeds were soaked in 50, 100 and 150 ppm (mg l^?1) aerated solutions of SA for 24 h and were dried back. Treated and untreated seeds were sown at 27 °C (optimal temperature) and at 15 °C (chilling stress) under controlled conditions. Performance of maize seedlings was hampered under chilling stress. But seed priming with SA improved the seedling emergence, root and shoot length, seedling fresh and dry weights, and leaf and root score considerably compared with control both at optimal and chilling temperatures. However, priming in 50 mg l^?1 SA solution was more effective, followed by priming in 100 mg l^?1 SA solution. Seed priming with SA improved the chilling tolerance in hybrid maize mainly by the activation of antioxidants (including catalase, superoxide dismutase and ascorbate peroxidase). Moreover, maintenance of high tissue water contents and reduced membrane permeability also contributed towards chilling tolerance.     

水稻苗期抗旱性指标的筛选

为探索水稻苗期抗旱性形态和生理机制，筛选苗期抗旱性指标，以15个水稻品种为试验材料，在干旱棚内系统研究了水、旱条件下苗期形态和生理指标的变化。结果表明，叶龄、心叶下倒数第1叶叶面积、叶鲜重、根长4个指标的相对值与反复干旱存活率显著或极显著相关，可作为苗期抗旱性的形态指标；超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性，氨基酸（AA）、抗坏血酸（AsA）、还原性谷甘肽（GSH）、可溶性蛋白质、丙二醛（MDA）含量8个指标的相对值与反复干旱存活率显著或极显著相关，可作为苗期抗旱性的生理指标。通过主成分分析确立了SOD酶活性、GSH含量、叶鲜重和叶龄4个指标相对值为水稻苗期抗旱性的综合指标，以反复干旱存活率为因变量，4个综合指标为自变量建立的回归方程对供试品种的抗旱性进行预测效果较好。     

抗旱浸种剂处理对小麦萌发和幼苗生长的影响

干旱胁迫下用抗旱剂处理小麦种子可以促进种子萌发和幼苗生长,提高出苗率,增加根冠比.处理后,各项生理生化指标均高于对照,可使幼苗在较低水势下保持正常生长,为小麦中后期发育打好基础.试验结果表明,本课题组研制的种子处理抗旱剂对小麦抗旱出苗的效果优于黄腐酸(FA).     

Improving Water Relations and Gas Exchange with Brassinosteroids in Rice under Drought Stress

Drought stress is the most pervasive threat to sustainable rice production and mainly disrupts membrane structure and cell-water relations. Exogenously applied brassinosteroids (BRs) may produce profound changes that may improve drought tolerance in rice. In this study, we monitored some physiological basis of the exogenously applied BRs in improving drought tolerance in fine grain aromatic rice ( Oryza sativa L.). Two BRs i.e. 28-homobrassinolide (HBL) and 24-epibrassinolide (EBL) were used both as seed priming and foliar spray. To prime, the seeds were soaked in 0.01 μ m aerated solution each of HBL and EBL for 48 h and dried back to original weight. Treated and untreated seeds were sown in plastic pots with normal irrigation in a phytotron. At four-leaf stage (3 weeks after sowing), plants were subjected to drought stress at 50 % field capacity by cutting down the water supply. For foliar spray, 0.01 μ m of HBL and EBL solutions were sprayed at five-leaf stage. Drought stress severely reduced fresh and dry weights, whilst exogenously applied BRs improved net CO₂ assimilation, water use efficiency, leaf water status, membrane properties, production of free proline, anthocyanins, soluble phenolics, but declined the malondialdehyde and H₂O₂ production. In conclusion, BRs application improved the leaf water economy and CO₂ assimilation, and enabled rice to withstand drought. Moreover, foliar spray had better effect under drought than seed treatments and of the two BRs, EBL proved more effective.