Response of maize (Zea mays L.) to potassium nano-silica application under drought stress

Abstract

To investigate the influence of potassium nano-silica (PNS) on maize plant under drought stress including non-stress (NS), moderate drought stress (MDS) and severe drought stress (SDS), a factorial experiment was conducted with completely randomized blocks with three replications. Drought stress decreased the concentrations in the shoot of phosphor (P), calcium (Ca), iron (Fe), zinc (Zn), manganese (Mn) and silica (Si) and nitrogen (N), P, Ca, Fe, Zn, copper (Cu), Mn and Si concentrations of seed. There was an increase in the concentration in the N seed and shoot potassium (K) concentration under drought stress. It was observed that applying PNS increased nutrient absorption. The highest concentration of N in the seed was obtained at 100?ppm PNS. The highest concentrations of seed K and N, Cu, Mn and Si in the shoot were found when 200?ppm of PNS was applied. Applying PNS had no significant effect on the concentrations of P, Ca, sodium (Na) and Cu in the seed, and of Ca and Na in the shoot. These findings demonstrate that the application of PNS can limit the negative effects of drought stress and improve plant’s resistance against drought stress.     

Brassinolide effects on maize (Zea mays L.) growth and yield under waterlogged conditions

Our aim was to assess if Brassinolide (BR) could ameliorate stress caused by waterlogging on maize. Two BR levels (with and without), two maize varieties [Ikom White (IKW) and Obatanpa-98 (Oba-98)] and three growth stages [control (WL_o), seedling stage (WL₁), and tasseling stage (WL₂)] were studied under waterlogging lasting 10 days. Maize growth and development were significantly (p?≤?.05) reduced by waterlogging stress under WL₁ than WL₂. Waterlogging stress at WL₁ adversely affected (p?≤?.05) the protein and relative water contents. The nitrogen (N) content among the plant partitions (leaves, stems, and grains) were reduced (p?≤?.05) at both silking and harvest. The beneficial effect of BR was more pronounced in Oba-98 with higher protein contents, dry matter yield, N-uptake and harvest index than IKW. Oba-98 was also better yielding than IKW. Thus, in a waterlogged soil, treatment of maize plants with BR at WL₁ could induce some tolerance.     

Exogenous application of humic acid and salicylic acid to alleviate seedling drought stress in two corn (Zea mays L.) hybrids

Efficacy of 1?mM humic (HA) and salicylic (SC) acids on SC 260 and SC 705 corn seedlings to alleviate drought stress via polyethylene glycol was studied via hydroponics at Shiraz University, Iran in a factorial, randomized design, with four replicates each. Under stress, SC 260 had higher electrolyte leakage compared to SC 705, and exogenous application of HA combined with SA decreased SC 705 electrolyte leakage. As a general trend, photosynthetic pigment content, relative water content, root and shoot length, mean number and diameter of central and peripheral root metaxylem, and K⁺ accumulation were higher in SC 705 treated with HA and SA compared to SC 260. Application of HA with SA could be an effective and low cost approach to ensure seedling establishment and plant growth in fields affected by soil drought in the early season, especially for the SC 705 corn hybrid in semi-arid regions.     

Effects of drought stress and rewatering on antioxidant systems and relative water content in different growth stages of maize (Zea mays L.) hybrids

Drought is a problem of the expanding universe which seriously influences crop production and quality. Approximately one-third of the cultivated area of the world suffers from constantly inadequate supplies of water. The present study aimed to determine the effects of drought and rewatering on activities of antioxidant enzymes, chlorophyll, proline, and relative water contents (RWC). In this experiment, six maize hybrids (Sc260, Sc370, Sc500, Sc647, Sc700, and Sc704) were examined in a pot study during the maize-growing season of 2011. Results indicated that the growth of hybrids was retarded under drought stress conditions and regained growth speed during rewatering. RWC, chlorophyll, and carotenoid contents were markedly decreased by the water deficit and reached normal values during rewatering in Sc647, Sc704, and Sc700. Our findings also indicated significantly higher activity levels of peroxidase and catalase and proline content in water-stressed plants than in well-watered plants, which decreased when the plants were rewatered, showing an inverse relationship to gluthatione reductase activity. According to the results, the better upregulation of the protective mechanism in Sc704 and Sc647 probably induced higher drought resistance. We concluded that antioxidant enzyme activity could provide a useful tool for depicting drought tolerance in maize hybrids in arid and semiarid regions.     

Effects of salicylic acid on growth and accumulation of phenolics in Zea mays L. under drought stress

The accumulation of total soluble and cell wall-bound phenolics and total soluble proteins in Zea mays plants exposed to drought stress and foliar spray of salicylic acid (SA) at 10^?4?mol/L and 10^?5?mol/L was investigated. Drought stress was imposed at the four-leaf stage for 10 days (30–35% field capacity). Dehydration of maize leaves was accompanied by the accumulation of both total soluble and cell wall-bound phenolics, reduction in leaf relative water content (LRWC), and shoot and root growth attributes. Foliar spraying of SA further augmented the content of total soluble and cell wall-bound phenolics and total soluble proteins content under drought stress. SA ameliorated the adverse effects of drought stress on LRWC, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, root length and root area. The accumulation of both soluble and cell wall-bound phenolics by foliar spray of SA may be a mechanism related to SA-induced drought stress tolerance in maize. It was concluded that foliar spraying of SA at 10^?5?mol/L can be highly economical and effective for modifying the effects of drought stress on maize at the four-leaf stage.     

干旱胁迫对玉米根系生长及根际养分的影响

通过盆栽模拟干旱试验，测定了干旱胁迫下玉米根系生长情况和根际土壤中速效N、P、K的含量。结果表明，干旱胁迫抑制了玉米拔节期和抽雄-开花期玉米根系的生长，减弱了玉米根系的吸收能力。干旱胁追下玉米根际NH4^＋-N、NO3^--N、速效P和速效K均发生根际富集现象。其中有效N和速效K含量高于正常供水．而速效P却呈现低于正常供水的趋势。干旱胁追抑制玉米根系生长、减弱根系吸收能力是玉米减产的重要原因。     

Kinetics of 15N-labelled nitrate uptake by maize (Zea mays L.) root segments

Abstract

Isotherms and kinetic constants of nitrate uptake by excised root segments from the apical root zone of 6-d-old maize seedlings pretreated with nitrate were investigated using ¹⁵N-labelled nitrate. The isotherms were resolved into two systems namely a multiphasic saturable system at substrate concentrations lower than 2 mol m^?-3 and a linear system at higher concentrations. The detailed analysis of the multiphasic saturable system suggested the existence of at least three phases, which followed the Michaelis-Menten kinetics. The I _max and K _m of each phase increase from the lower phase to the upper phase. The distance from the root tip and the presence of stele affected considerably the linear system but only slightly the saturable system.     

Arbuscular mycorrhizal fungi affect the growth,nutrient uptake and water status of maize (Zea mays L.) grown in two types of coal mine spoils under drought stress

Drought stress greatly affects the growth and development of plants in coal mine spoils located in the Inner Mongolia grassland ecosystem. Arbuscular mycorrhizal fungi (AMF) can increase plant tolerance to drought. However, little is known regarding the contribution of AMF to plants that are grown in different types of coal mine spoils under drought stress. To evaluate the mycorrhizal effects on the drought tolerance of maize (Zea mays L.) grown in weathered (S1) and spontaneously combusted (S2) coal mine spoils, a greenhouse pot experiment was conducted to investigate the effects of inoculation with Rhizophagus intraradices on the growth, nutrient uptake, carbon:nitrogen:phosphorus (C:N:P) stoichiometry and water status of maize under well-watered, moderate and severe drought stress conditions. The results indicated that drought stress increased mycorrhizal colonization and decreased plant dry weights, nutrient contents, leaf moisture percentage of fresh weight (LMP), water use efficiency (WUE) and rehydration rate. A high level of AMF colonization ranging from 65 to 90% was observed, and the mean root colonization rates in S1 were lower than those in S2. In both substrates, inoculation with R. intraradices significantly improved the plant growth, P contents, LMP and WUE and decreased the C:P and N:P ratios of plants under drought stress. In addition, maize grown in S1 and S2 exhibited different wilting properties in response to AMF inoculation, and plant rehydration after drought stress occurred faster in mycorrhizal plants. The results suggested that inoculation with R. intraradices played a more positive role in improving the drought stress resistance of plants grown in S2 than those grown in S1. AMF inoculation has a beneficial effect on plant tolerance to drought and effectively facilitates the development of plants in different coal mine spoils.     

Salinity stress on various physiological and biochemical attributes of two distinct maize (Zea mays L.) genotypes

Present study investigates the effect of salinity stress on physiological and biochemical characteristics of two maize genotypes cultivated under controlled growth conditions. The selected maize genotypes being salt-tolerant and salt-sensitive were respectively designated as Sahwal-2002 and Sadaf. The experiment was conducted in triplicates, two varieties, three priming treatments and two salinity levels, in the Government College University, Faisalabad. The antioxidants activity was measured by comparing the tolerance in response to acute and prolonged salinity treatment. The difference of genotype with salinity tolerance as well as seed priming with phenylalanine were not dependent on antioxidant activity when salt exposure was prolonged. The results show that an indirect relationship was present for PAL seed priming and oxidative damage due to salt. The antioxidant enzymes present in plant effectively reduced the oxidative damage of salt and thus, increased the overall crop yield.     

Alleviation of drought stress in maize (Zea mays L.) by using endogenous endophyte Bacillus subtilis in North West Himalayas

ABSTRACT

In the present study, we reported the isolation and molecular characterisation of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-producing endophyte and its effect on alleviating drought stress in maize. Ten morphologically distinct indigenous plant growth-promoting rhizobacteria (PGPR) from maize roots and rhizosphere were screened for multiple plant growth-promoting (PGP) traits, and of ten, two strains (DHK and B1N1) possessing maximum PGP traits were evaluated at three water stress regimes in maize: (i) 80% field capacity (FC), (ii) 60% FC, and (iii) 40% FC for 45 days, starting 15 days after sowing to the maturity. Inoculation of DHK strain with maize at 80% FC induced a significant increase in plant biomass (root biomass, 86.67%; shoot biomass, 111.63%) together with decreased reactive oxygen species and increased activity of antioxidant enzymes (superoxide dismutase, 14.11?U/g fresh weight; peroxidase, 1.14?U/g fresh weight and catalase; 14.91?U/g fresh weight) compared to uninoculated control at same water regime (80% FC). The derivative strain also significantly accrued nutrients in maize and enhanced total chlorophyll and amino acid content in comparison with non-inoculated plants. 16S rDNA analysis of DHK strain revealed its lineage to Bacillus subtilis. Present investigations demonstrated the potential of the bacterial partner in alleviating drought stress in maize.     

玉米的生理指标对土壤水分有效性的响应

Knowledge of plant responses to soil water availability is essential for the development of effcient irrigation strategies.However,notably different results have been obtained in the past on the responses of various physiological indices for different plants to soil water availability.In this study,the responses of various plant processes to soil water availability were compared with data from pot and field plot experiments conducted on maize(Zea mays L.).Consistent results were obtained between pot and field plot experiments for the responses of various relative plant indices to changes in the fraction of available soil water(FASW).A threshold value,where the relative plant indices began to decrease with soil drying,and a lower water limit,where the decline of relative plant indices changed to a very slow rate,were found.Evaporative demand not only influenced the transpiration rate over a daily scale but also determined the difference in transpirational response to soil water availability among the transient,daily and seasonal time scales.At the seasonal scale,cumulative transpiration decreased linearly with soil drying,but the decrease of transpiration from FASW = 1 in response to water deficits did not affect dry weight until FASW = 0.75.On the other hand,the decrease in dry weight was comparable with plant height and leaf area.Therefore,the plant responses to soil water availability were notably different among various plant indices of maize and were influenced by the weather conditions.     

Root zone selenium reduces cadmium toxicity by modulating tissue-specific growth and metabolism in maize (Zea mays L.)

The effects of selenium (Se) cadmium (Cd) interactions on plant growth and metabolism are not fully clear. In the present study, we assessed whether Se could alleviate the toxic effects of Cd on growth and metabolism of maize. Seeds of maize variety FH-985 were sown in pots filled with sand treated with CdCl₂ (0, 50 and 100 µM) and Se (0, 2 and 4 mg L^?1) through Hoagland’s nutrient solution. Low Se (2 mg L^?1) increased germination percentage and rate, while high Se (4 mg L^?1) increased fresh and dry biomass under Cd stress. Interestingly, all Se concentrations were effective in alleviating the toxic effects of Cd on photosynthetic pigments, whereas higher Se mitigated the Cd-induced oxidative stress and increased flavonoids both in the shoots and roots while phenolics in the roots. The results demonstrated that root zone Se altered tissue-specific primary metabolism in maize. Furthermore, low Se mitigated the Cd-induced decrease in total proteins in the root. Overall, Se-mediated decrease in the oxidative stress in the shoots while increase of secondary metabolites in the roots helped the plants to grow faster at early growth stage and caused increase in the biomass under different Cd regimes.     

Denitrification with and without maize plants (Zea mays L.) under irrigated field conditions

The study was conducted under irrigated field conditions to examine the effect of maize plants on denitrification. Both planted and unplanted field plots received 150kgNha^–1 as urea. In a third treatment, which was also planted and received urea at 150kgNha^–1, the soil nitrate N content was brought up to equal to that in the unplanted plots by applying additional doses of N as calcium nitrate. Soil cores were collected 24 and 72h after irrigation and the denitrification rate was measured by the acetylene inhibition method. Nitrate-N content, aerobically mineralizable C, microbial biomass carrying capacity and denitrification potential were also studied on field-moist soil. Maize plants grown under field conditions always had the potential to increase denitrification in conditions of both high and low water-filled porosity. When nitrate-N content of the planted soil decreased due to plant uptake, denitrification was reduced in the planted soils. However, when nitrate-N uptake by plants was compensated through additional doses of nitrate fertilizer, denitrification was always higher in planted than unplanted soil. The stimulatory effect of plants on denitrification was observed at both high and low soil nitrate-N concentrations, though it was more pronounced at high nitrate-N levels. The effect of plants on denitrification and related parameters was confined to the root zone. Received: 15 April 1996     

拔节期淹水玉米的生理性状和产量形成

为了探明夏玉米拔节期对淹水历时的响应规律,采用大田环境下无底测坑试验,在玉米拔节期设置不同的淹水天数(1、2、3、5、7 d),分析了淹水历时对夏玉米生长发育、灌浆过程、物质分配及产量性状的影响。结果表明,玉米拔节期淹水抑制玉米的营养期发育,淹水1、2、3、5、7d的平均株高分别比非涝渍环境下玉米(CK)降低2.26%、2.26%、2.45%、11.36%和10.17%;平均叶面积指数LAI分别降低23.79%、18.93%、13.04%、32.74%和34.27%;玉米拔节期淹水5 d以上,植株矮而黄。在植株生理反应方面,淹水3 d后测定结果表明,淹水1、2、3 d的叶绿素质量分数比CK高,根系活力增强,而淹水5d和7d叶绿素质量分数和根系活力下降。玉米灌浆至乳熟期叶绿素测定结果表明,淹水5 d以上处理的叶绿素质量分数仍较CK降低10.87%,表明受淹5 d以上,叶绿素质量分数降低并无法恢复。玉米拔节期受淹影响其后期灌浆过程中的籽粒质量,同一时间的淹水1、2和3 d与对照籽粒质量比较接近,淹水5 d较低,淹水7 d为最低。玉米穗长和穗粗随淹水历时呈减小的趋势,但各处理间无显著差异(P0.05)。淹水使玉米出现较长的秃尖,淹水1、2、3、5 d的秃尖长度为CK的2倍左右,淹水7 d的秃尖长度为CK的5倍;淹水历时越长,玉米穗长、穗粒质量、穗质量和百粒质量的减幅就越大,淹水1、2、3、5、7的玉米产量分别降低16.58%、16.65%、26.11%、34.32%和39.01%。玉米拔节期淹水5 d以上,严重影响玉米正常生长,造成产量显著降低。研究结果为涝渍灾害监测和灾损快速评估以及涝渍排水标准确定提供参考。     

不同生长时期干旱胁迫甘薯根系生长及荧光生理的特性比较

【目的】干旱胁迫是我国甘薯生产所面临的重要问题,本试验旨在为研究甘薯的抗旱生理机制,明确甘薯水分临界期,减轻干旱影响和优化甘薯生产管理提供科学依据。【方法】利用人工旱棚,设置甘薯正常供水与前期、 中期和后期(即定栽后15 d、 55 d、 95 d)干旱胁迫四个处理(田间持水量的8%~10%,每次胁迫持续15天)。用Epson v700扫描仪调查了不同处理三个不同时期根系发育,用M-PEA(Hansatech,英国)测定了叶片荧光生理参数。【结果】前期和中期干旱均显著降低了甘薯地上和地下部生物量(P0.05),而后期干旱影响较小,其规律表现为前期＞中期＞后期。其中,前期干旱甘薯总生物量减少约50%; 中期干旱造成地上和地下部分别减少38.4%和31.1%; 后期干旱地上和地下部减少均约10%左右。各个时期干旱胁迫均显著影响甘薯根系发育(P 0.05)。与正常供水相比,前期干旱胁迫总根长、 总表面积和总体积分别减少49.5%、 55.7%和43.2%,中期干旱胁迫分别减少27.5%、 27.0%和28.9%,后期干旱胁迫影响较小。不同时期干旱胁迫对叶绿素荧光参数的影响不同,前期和中期胁迫处理测定值差异显著,叶绿素荧光动力学曲线发生明显变化,后期未达显著性水平。与对照相比,前期和中期的PSⅡ综合荧光参数指标Fm、 Fv/Fm、 PI(ABS)分别减少了36.4%、 15.6%、 44.3%和14.7%、 3.8%、 22.6%; 指示反应中心活性的参数φEo分别减少7.7%、 3.4%,而反映电子传递速率的参数Vj、 dV/dto分别增加了33.1%、 32.1%和19.2%、 17.1%,这些荧光参数的变化表明,干旱胁迫导致PSⅡ结构受损,反应中心受到伤害,光能转化效率降低,电子传递受阻。【结论】甘薯水分临界期处于前中期,实际中应特别加强甘薯前期的水分供应。     

Relationship between fatty acid profile and vitamin E content in maize hybrids (Zea mays L.)

The balance between the vitamin E (tocochromanols) and polyunsaturated fatty acid (PUFA) contents mainly determines the susceptibility to lipid peroxidation and the storage stability of corn oil. In 1997, field experiments were conducted at two different locations to evaluate a collection of 30 corn hybrids for fatty acid profiles and tocochromanol contents. Hybrids differed significantly (p < 0.01) for major fatty acids, as well as for tocochromanol contents and composition. The major fatty acids were palmitic, oleic, and linoleic acids, whose contents were in the ranges 9.2-12.1%, 19.5-30.5%, and 53.0-65.3%, respectively. The tocopherol contents ranged as follows: alpha-tocopherol, 67-276 mg (kg of oil)(-1); beta-tocopherol, 0-20 mg (kg of oil)(-1); gamma-tocopherol, 583-1048 mg (kg of oil)(-1); delta-tocopherol, 12-71 mg (kg of oil)(-1); total tocopherol, 767-1344 mg (kg of oil)(-1). gamma-Tocopherol was the predominant derivative among all tocopherols. The tocotrienol contents were in the ranges 46-89, 53-164, and 99-230 mg (kg of oil)(-1) for alpha-, gamma-, and total tocotrienol contents, respectively. The tocotrienol profile was not characterized by the predominance of any tocotrienol homologue. alpha-Tocopherol was positively correlated with PUFA (r = 0.41) and with the vitamin E equivalent (vit E equiv) (r = 0.84), and it was not correlated with gamma-tocopherol. gamma-Tocopherol was highly correlated with total tocopherol and tocochromanol contents (r = 0.93 and r = 0.90, respectively), indicating that the contribution of this vitamer to the total tocochromanol content is the most important among all tocochromanols. The high positive correlation found between the vit E/PUFA ratio and the vit E equiv, as well as the absence of correlation between this ratio and PUFA indicates that a higher vit E/PUFA ratio can be easier achieved be increasing the vitamin E content than by modifying fatty acid profile in corn oil.     

氮肥种类和淹水胁迫对砂姜黑土区玉米苗期生长和养分吸收的影响

采用盆栽土培方法,比较0~14 d持续淹水胁迫条件下,不同形态的氮肥以及施氮、磷和钾肥对砂姜黑土区富钾低肥土壤上种植玉米苗期植株的地上部生物量、氮、磷和钾含量与累积量的影响。结果表明,在玉米3叶1心期(淹水胁迫处理前),施硝酸钾处理地上部的生物量明显高于除施硝酸铵处理以外的其它处理(P0.05)。在3个缺素处理中,不施钾处理地上部的生物量明显低于不施磷处理(P0.05),但与不施氮处理差异不显著。在淹水胁迫过程中,施肥和淹水胁迫的交互作用影响不显著,在淹水胁迫处理7 d时,施不同形态的氮肥以及施氮、磷和钾肥显著影响玉米地上部的生物量和氮累积量(P0.05),并极显著影响磷累积量和钾累积量(P0.01);淹水胁迫也显著降低了此时玉米植株地上部的氮累积量,并极显著降低其钾累积量(P0.01),且当胁迫处理延长至14 d时,淹水胁迫还引起生物量和磷累积量的显著下降(P0.05)。延长淹水胁迫持续时间,对生物量、氮累积量和钾累积量的肥效差异与胁迫的抑制效应分别呈现加大和增强的趋势。比较F值大小可知,在淹水胁迫处理7 d时,氮肥种类是玉米地上部生物量、氮和磷累积量变化的主要诱因;而当胁迫处理延长至14d时,淹水胁迫则上升为主要决定因子。与此不同,胁迫处理开始后,淹水胁迫始终是钾累积量变化的主要决定因子。在淹水胁迫条件下,尿素可能是有利于提高富钾低肥土壤苗期玉米耐淹水胁迫性的氮肥种类。     

Ameliorative effect of Lantana camara biochar on coal mine spoil and growth of maize (Zea mays)

The aftermath of surface mining is a wasteland deprived of vegetation, soil structure and biodiversity. The unearthed overburden material is nutrient deprived and can only support the growth of invasive weeds such as Lantana camera which often cause allelopathy. The aim of the study is to prepare biochar from these noxious weeds and use it as an amendment for the mine spoil reclamation. Lantana biochar (LB) was prepared and applied to mine spoil, and Zea mays L. growth on biochar amended mine spoil was monitored for three months. Biochar application in a coal mine spoil using LB is comparatively de novo approach for reclamation practitioners. LB was prepared at varying temperature (250, 350 and 450℃) and residence times (30, 45 and 60 min) and characterized. After characterization, the most recalcitrant biochar at 450℃ for 60 min was chosen for application for the study. A pot trial was conducted to study the effect of LB at 0, 5, 10, 20 and 30 g kg⁻¹ dosage on the yield of Zea mays and mine spoil properties. Significant ameliorative effects were observed with increase in organic carbon content (2.9 times), cation exchange capacity (2 times), water holding capacity (0.13 times) and decrease in bulk density (0.5 times) in the mine spoil. The seedling vigour index and germination also increased significantly (p < .05) at 30 g kg⁻¹ biochar treatment compared to control. The study concluded that LB has the potential to remediate coal mine spoils and promote re-vegetation in degraded land.     

Estimation of phosphorus uptake capacity by different zones of the primary root of soil-grown maize (Zea mays L.)

A method is described which allows determination of the nutrient uptake capacity by different zones of individual roots of soil-grown plants. Examples are given for phosphorus uptake by different zones of the primary root of maize. Agar strips with labelled phosphorus (³²P) are placed on the soil-root interface of root zones of different age. After 24 h autoradiographs are made of the soil-root interface and phosphorus uptake rates determined by plant analysis. Along the primary root the relative phosphorus uptake capacity declines per unit root length from 100% in 1 day old root zones to about 25–30% in 26 day old root zones. The change in the extension of the phosphorus (³²P) depletion zone along the root axis indicates that the uptake capacity for phosphorus of root hairs was maximal upto 4 days and declined thereafter. The decline in capacity for phosphorus uptake from apical to basal root zones probably reflects the decline in root hair viability. The relative high uptake capacity in basal root zones is therefore at least partially due to the uptake capacity of the cortical cells.