Response of Alfalfa under Salt Stress to the Application of Potassium Sulfate Nanoparticles

A greenhouse study was conducted to explore the effect of various rates of potassium sulfate (K2SO4) nanoparticles on alfalfa (Medicago sativa L.) growth and physiological response under salt stress. One salt-tolerant genotype (Mesa-Sirsa) and one salt-sensitive genotype (Bulldog 505) were selected based on germination under salt and were planted in pots containing 2 kg of sand. The two genotypes were subjected to 0 and 6 dS·m-1 salt levels using CaCl2·2H2O: NaCl (2:1) mixed with Hoagland solution. Three K2SO4 nanoparticle treatments consisting of, 1/4, 1/8, and 1/10 of the potassium (K) level in full strength Hoagland solution (235 mg·L-1) were applied. Adding K2SO4 nanoparticles at the 1/8 level resulted in the highest shoot dry weight, relative yield, root length and root dry weight in both genotypes. The different rates of K2SO4 nanoparticles affected significantly Na/K ratio and the concentrations of Calcium (Ca), Phosphorus (P), Copper (Cu), Manganese (Mn), and Zinc (Zn) in plant tissue. The application of K2SO4 nanoparticles at the 1/8 rate enhanced the plant’s physiological response to salt stress by reducing electrolyte leakage, increasing catalase and proline content, and increasing antioxidant enzymes, activity. These results suggest that the application of K nanoparticles may have better efficiency than conventional K fertilizers in providing adequate plant nutrition and overcoming the negative effects of salt stress in alfalfa.

Salinity Stress Alleviation by Foliar Bio-Stimulant, Proline and Potassium Nutrition Promotes Growth and Yield Quality of Garlic Plant

Soil salinity is one of the major yield-limiting factors for crop production in many agricultural regions all over the world. Besides following efficient management practices at the field scale to reduce accumulation of salts in the effective root-zone, the effective use of treatments to alleviate the effects of salinity stress and improve crop salt tolerance is a promising solution to ensure crop production in such adverse conditions. A field experiment was carried out to investigate the effect of foliar spray with plant-based biostimulant (i.e. with and/or without 3% yeast extract), three levels of proline (0, 25, and 50 mM), and combined with potassium fertilizers, as potassium sulfate, 48% K2O (0, 50, and 100 kg/fed.) on growth promotion, chemical composition of garlic leaves, bulb quality parameters as well as yield and its components of garlic plant grown under moderate saline soil. Results revealed that the interaction between foliar spray with yeast extract at 3% and proline at 50 mM combined with proper K level at 100 kg/fed., was the best interaction treatment for increasing vegetative growth parameters, i.e. plant height, number of leaves per plant, and mineral contents (N, P, K, S, Ca and Mg in leaves), and proline content of garlic leaves after 135 days from planting time, total yield/fed., and garlic yield quality parameters at harvesting time. In conclusion, the detrimental effects of salinity stress can be alleviated by stress tolerance-inducing compounds, such as yeast extract and proline with proper application rate of K fertilization during the growing season of garlic crop.

Effects of Application of Nitrogen, Potassium and Glycinebetaine on Alleviation of Water Stress to Summer Maize

A pot experiment was conducted under water deficit and adequate water-supplied conditions with two maize genetypic varieties （Shaandan 9 and Shaandan 911） to study the effects of nitrogen, potassium and glycinebetaine （GlyBet） on the dry matter and grain yields as well as water use efficiency （WUE）. Determinations were made at different stages of the two varieties for revealing the function of these factors in increasing plant resistance to drought. Results showed that under a water-stressed condition, dry matter and grain yield were significantly reduced. However, the response of the two varieties to water stress was different： Shaandan 9 was significantly higher in dry matter and grain yields, and therefore could be regarded as a drought-resistant variety compared to Shaandan 911.Application of nitrogen, potassium and glycinebetaine raised dry matter and grain yield to different levels, and thereby alleviated the water stress and increased water use efficiency. These effects were higher for Shaandan 911 than for Shaandan 9. Under water-stressed conditions application of N fertilizer, either at low rate or at high rate, significantly increased dry matter, grain yield and water use efficiency. A significant different effect was found for Shaandan 911 between N rates, but not so for Shaandan 9. However, with supplemental water supply, effects of N fertilization were obviously decreased, showing that in addition to supplying nutrient, N fertilizer has a function in increasing drought-resistance of the crop. Potassium and glycinebetaine exhibited a remarkable function in increasing dry matter and grain yields as well as water use efficiency under water stress while such effects were obviously declined, even vanished, with supplemental water supply, indicating the important contribution of these factors in rise of drought-resistance ability of a crop.

Ameliorative effects of potassium on drought-induced decreases in fiber length of cotton(Gossypium hirsutum L.) are associated with osmolyte dynamics during fiber development

Fiber length of cotton(Gossypium hirsutum L.)decreases under drought stress,potassium(K)could diminish the decreased caused by drought,but the mechanism associated with this alleviation effect is not clear.We evaluated the effect of K on fiber elongation using two cotton cultivars,Simian 3 and Siza 3,grown in well-watered and drought-stressed conditions.Potassium fertilizer(K2O)was applied 0,150,or 300 kg ha?1 in each growing condition.Drought stress reduced the final fiber length due to a decline in the maximum rate of rapid elongation(Vmax,mmday?1).The application of K alleviated the droughtinduced fiber length reduction by increasing Vmax.At 10 and 15 days post-anthesis(DPA),drought significantly reduced osmotic potential(OP)and increased K+and malate contents at all K rates,relative to well-watered conditions,which was associated with increased activities of phosphoenolpyruvate carboxylase(PEPC),V-ATPase,PPase,and PM H+-ATPase in cotton fiber.However,the relative contribution of K+and malate to OP declined under drought in comparison with well-watered condition.Compared with control without K,K application decreased OP and increased the accumulation of osmolytes(K+,malate and soluble sugar)as well as the activities of related enzymes in fiber irrespective of water treatments.Moreover,K application increased osmotic adjustment during drought,and improved the contribution of K+and malate to OP,especially under drought stress.This study showed that drought decreased fiber length by reducing Vmax,and K application ameliorates the decline in fiber elongation due to drought by enhancing osmolytes accumulation and their contribution to OP in fiber cells.

Maintenance of mesophyll potassium and regulation of plasma membrane H^+-ATPase are associated with physiological responses of tea plants to drought and subsequent rehydration

Drought stress is one of the main factors limiting yield in tea plants. The plant cell's ability to preserve K^+homeostasis is an important strategy for coping with drought stress. Plasma membrane H^+-ATPase in the mesophyll cell is important for maintaining membrane potential to regulate K^+transmembrane transport. However, no research to date has investigated the possible relationship between plasma membrane H^+-ATPase and mesophyll K^+retention in tea plants under drought and subsequent rehydration conditions. In our experiment, drought stress inhibited plasma membrane H^+-ATPase activities and induced net H^+influx, leading to membrane potential depolarization and inducing a massive K^+efflux in tea plant mesophyll cells. Subsequent rehydration increased plasma membrane H^+-ATPase activity and induced net H^+efflux, leading to membrane potential hyperpolarization and thus lowering K^+loss. A first downregulated and then upregulated plasma membrane H^+-ATPase protein expression level was also observed under drought and subsequent rehydration treatment, a finding in agreement with the change of measured plasma membrane H^+-ATPase activities. Taken together, our results suggest that maintenance of mesophyll K^+in tea plants under drought and rehydration is associated with regulation of plasma membrane H^+-ATPase activity.

Effect of Plant Growth Stimulants on Alfalfa Response to Salt Stress

Salinity is a major impediment to crop production. This study was undertaken to compare the effect of seaweed extract, humic acid, and potassium sulfate nanoparticles in alleviating salt stress in Alfalfa (Medicago sativa L.). Seeds of ten alfalfa genotypes were germinated in a growth chamber at five salt concentrations (0%, 0.5%, 1.0%, 1.5%, and 2.00%). Salt concentrations above 1% reduced seed germination by more than 70% in most genotypes. One salt tolerant genotype (Mesa-Sirsa) and one salt sensitive (Bulldog 505) were selected and planted in greenhouse pots containing 2 kg of sand and subjected to two salt levels (10 and 15 dS· m-1). Four treatments consisting of 1) control (Hoagland solution, no-salt), 2) seaweed extract at 4 Kg·ha-1, 3) humic acid at 28 L· ha-1, and 4) potassium sulfate at 300 Kg· ha-1. Plant biomass was reduced under both salt concentrations in both genotypes, with a greater magnitude in the salt sensitive genotype. Application of seaweed extract resulted in higher relative water content and proline under both salt concentrations (10 and 15 dS·m-1) in the salt sensitive genotype, and lower electrolyte leakage in both salt tolerant and salt sensitive genotypes, under both salt concentrations. Seaweed extract also resulted in higher catalase and SOD activities in both genotypes under 10 dS·m-1. Catalase and SOD activities were associated with significantly (p < 0.01) reduced electrolyte leakage and increased shoot dry weight. Overall, seaweed extract seemed to have a positive effect in alleviating salt stress in alfalfa.

Response to Inoculation with Arbuscular Mycorrhizal Fungi of Two Tomato (Solanum lycopersicum L.) Varieties Subjected to Salt Stress under Semi-Controlled Conditions

Salinity is a major problem that seriously impacts agricultural production, particularly that of tomato (Solanum lycopersicum L.). However, the plant has the ability to associate with Arbuscular Mycorrhizal Fungi to better tolerate salt stress. Thus, thanks to the extension of the AMF hyphae, the hydromineral nutrition and the tolerance to excess toxic ions (Na+ and Cl-) of the plant are optimized. In this context, the contribution of AMF to the salt stress tolerance of two tomato varieties under semi-controlled conditions was studied. To do this, the frequency and intensity of mycorrhization, the relative mycorrhizal dependency, the survival rates, the aerial and root dry weights, the mineral (P, K+, Na+) and proline contents of the plants subjected to four levels of salinity [0, 70, 140 and 210 mM of NaCl] were evaluated. All the parameters assessed appeared to be dependent on the variety, the fungal strain and the NaCl concentration. With the Lady Nema variety, inoculation with the Claroideoglomus etunicatum strain at [NaCl 140 mM] resulted in the highest frequencies (54%), intensities (40.47%), and relative mycorrhizal dependencies (19.65%). This same symbiotic couple recorded high survival rates (55%) and aerial (2.03 g) and root (0.50 g) dry weights. Significant contents of K+ (Leaves: 7.5 mg⋅g-1;Roots: 4.4 mg⋅g-1 of dry matter), P (Leaves: 15.15 mg⋅g-1 of dry matter) and proline (975 nmoles⋅g-1 of fresh matter) were also recorded by this pair, with the lowest Na+ contents (Leaves: 1.93 mg⋅g-1;Roots: 0.96 mg⋅g-1 of dry matter). For the Mongal variety, at [NaCl 140 mM], the highest frequencies (50.36%), intensities (35.14%) and relative mycorrhizal dependencies (43.95%) were obtained thanks to inoculation with Rhizophagus fasciculatus. The highest survival rates (59%) and aerial (2.58 g) and root (0.79 g) dry weights were also obtained with this symbiotic couple. The contents of K+ (Leaves: 6.1 mg⋅g-1;Roots: 3.09 mg⋅g-1 of dry matter), P (Leaves: 12.49 mg⋅g-1 of dry matter) and proline (942 nmoles⋅g-1 of fresh matter) the most important and those in Na+ the lowest (Leaves: 2.03 mg⋅g-1;Roots: 1.53 mg⋅g-1 of dry matter) were also recorded for this same pair. Thus, the best fungal partner for the Lady Nema variety is C. etunicatum, followed by F. mosseae and R. fasciculatus, while for the Mongal variety it is R. fasciculatus, followed by C. etunicatum and F. mosseae.

外施硝态氮肥对玉米苗期涝害的缓解效应

本试验以玉米郑单958为材料,研究叶面喷施不同硝态氮肥对苗期涝害的缓解效应。结果表明,与对照(CK)相比,淹水处理(T1)第7天时幼苗株高、鲜重和干重显著降低;淹水+叶面喷施KNO3(T2)处理下幼苗地上部和根的鲜重、干重分别比T1显著增加21.7%、45.5%和32.9%、49.6%,淹水+叶面喷施Ca(NO_(3))_(2)(T3)处理下幼苗鲜重、干重比T1略有增加。与CK相比,T1处理叶片MDA和H2O2含量第5天后均显著增加,之前也有所增加;外施硝态氮肥明显降低过氧化胁迫,第5天时T2处理叶片的MDA和H_(2)O_(2)含量分别比T1下降9.1%、14.9%,T3处理分别比T1下降2.1%和14.6%。与CK相比,T1处理叶片可溶性糖和可溶性蛋白含量略有降低,但脯氨酸含量显著增加;T2处理第1天和第5天时可溶性糖含量比T1处理显著增加44.5%和23.8%,T3处理第1天时可溶性糖含量比T1显著增加36.5%,脯氨酸含量仅在T2处理下显著增加。与CK相比,T1处理叶片抗氧化酶活性均有降低,且多半达到显著水平;外施硝态氮肥提高淹水胁迫下的抗氧化酶活性,T2处理第5天时叶片SOD、POD和CAT活性分别比T1提高25.1%、12.4%和22.1%;T3处理第5天时SOD和POD活性分别比T1提高6.4%和52.9%,但CAT活性略有下降。可见,外施KNO3比Ca(NO_(3))_(2)对涝害的缓解效应更显著。

不同生育期干旱胁迫条件下施钾对水稻生理性状和产量的影响

明确不同生育时期干旱胁迫对水稻影响与钾素调控干旱胁迫机制,可为水稻的钾素管理和节水抗旱提供理论依据。采用不同时期水分和钾素管理两因素盆栽试验,设置施钾(+K)、不施钾(–K)两个钾肥处理;有效分蘖期干旱胁迫(TD)、孕穗期干旱胁迫(BD)、灌浆期干旱胁迫(MD)和正常灌溉(WW)四个水分处理,分析在不同生育期干旱胁迫钾肥对水稻产量和生理性状的影响。结果表明:干旱胁迫显著降低了稻谷产量,TD、BD、MD处理相较于WW处理,在–K条件下稻谷分别减产53.9%、45.2%、7.6%;而在+K条件下稻谷分别减产28.3%、16.5%和5.9%,不同生育期的干旱胁迫对产量的影响程度为:TD>BD>MD,且缺钾加剧了水分亏缺的负面影响。同时,干旱胁迫也造成冠层蒸腾速率、叶水势和叶片净光合速率下降,减少干物质积累,TD、BD处理相较于WW处理,叶片生物量分别平均降低42.9%、31.2%;茎鞘生物量分别降低43.8%和38.0%。不同生育期水分亏缺对生物量的影响为:TD>BD。而缺钾不仅造成净光合速率下降,也使叶面积和叶绿素含量降低,植株截获光辐射能力显著下降,干物质积累量减少,相较于+K处理,TD、BD及相应同时期WW处理的叶片生物量在缺钾条件下分别降低52.6%、32.7%、42.1%、31.2%,茎鞘生物量分别降低55.3%、63.6%、52.2%、28.0%,干旱胁迫加剧缺钾的消极影响。综上,干旱胁迫会降低净光合速率与叶水势,造成水稻减产,其中有效分蘖期和孕穗期的减产效应较灌浆期明显;缺钾不仅降低叶片净光合速率,也减少叶面积与叶绿素含量,水稻同化积累物质能力下降,抗旱性显著降低。

低钾胁迫下过表达NtCaM10对烟草生长及钾素吸收的影响

为探究低钾胁迫下过表达NtCaM10基因对烟草生长及钾素吸收的生理与分子调控机制,以野生型烟草K326(WT)及过表达NtCaM10转基因K326为试验材料,设置两个钾水平,5 mmol/L(常钾)、0.15 mmol/L(低钾),分析低钾胁迫下NtCaM10基因的表达模式及启动子活性,测定相关生理生化指标、钾离子吸收相关基因的相对表达量及各部位钾含量。结果表明,低钾胁迫后NtCaM10基因的相对表达量显著上升、启动子活性被激活。与常钾水平相比,低钾水平下WT和转基因株系的鲜质量及根系长度均显著降低。在低钾水平下,WT生长受抑制的效果更加明显,NtCaM10过表达3个转基因株系的平均鲜质量相比WT显著提高了57.44%,平均根系长度显著提高了35.77%,转基因系中丙二醛的积累显著低于WT,SOD、POD、CAT的活性均显著高于WT,NtCaM10过表达烟草中的NtHAK1、NtHAK5、NtKC1、NtNKT2的平均相对表达量显著上调,增幅分别为56.60%、81.84%、98.08%、638.89%,过表达NtCaM10烟草根部和地上部的平均钾素积累与WT相比显著提高了21.59%和32.36%。NtCaM10基因参与烟株对低钾胁迫的响应,过表达NtCaM10可以通过调节烟草的抗氧化酶活性和钾离子吸收与转运相关基因的表达来正向调节烟草对低钾胁迫的耐受性。

异源四倍体油菜HAKs家族核心基因的鉴定及其功能初步解析

[目的]HAKs家族基因编码高亲和力K^(+)转运蛋白,在K^(+)吸收和运输过程中发挥关键作用。鉴定甘蓝型油菜HAKs家族核心基因,研究不同养分胁迫下核心基因表达的响应,不仅可加深对HAKs功能的理解,也可为HAKs介导油菜营养胁迫抗性的遗传改良提供基因资源参考。[方法]对甘蓝型油菜HAKs基因家族进行全基因组鉴定和分析,其中包括系统发育关系、基因结构、保守基序、染色体定位、顺式作用元件。利用不同养分胁迫下的转录组数据对HAKs家族基因进行差异基因表达分析,并用Cytoscape构建共表达网络图。以低钾抗性品系“H280”和低钾敏感品系“L49”为材料,在低钾胁迫下进行水培试验,使用ICP-MS分析了“H280”和“L49”根部K+含量,RT-qPCR以及亚细胞定位分析了低钾胁迫下BnaA7.HAK5的响应和功能。[结果]在甘蓝型油菜中共鉴定到40个HAKs家族成员。对其进行进化关系分析,发现它们的Ka/Ks值均小于1.0。顺式作用元件分析表明,MYB和激素响应顺式作用调控元件ABRE在HAKs家族基因的启动子区域高度富集。共线性分析表明在进化过程中,甘蓝型油菜中绝大多数的HAKs基因保存完整。差异表达基因分析发现,大部分HAKs家族基因的表达水平受低钾胁迫的显著诱导。共表达网络分析表明,BnaA7.HAK5响应油菜低钾胁迫。RT-qPCR结果显示,BnaA7.HAK5在抗低钾品系“H280”根中的表达量显著高于低钾敏感品系“L49”。亚细胞定位结果显示,BnaA7.HAK5定位在细胞质膜上。[结论]甘蓝型油菜共有40个BnaHAKs基因,BnaHAKs基因响应低钾或盐等养分胁迫。定位在细胞质膜上的BnaA7.HAK5在低钾条件下的表达量显著上调,且在“H280”和“L49”油菜品系根部的表达量差异显著,表明BnaA7.HAK5在油菜高亲和性钾离子的吸收和转运中发挥重要功能。

水分和氮磷钾胁迫处理苗期水稻对褐飞虱抗性的影响

【目的】探究水源和食物对褐飞虱死亡速率的影响,探究不同浓度养分处理下的水稻幼苗对褐飞虱的抗性和趋避性,为综合应用田间水肥管理防治褐飞虱提供理论依据。【方法】以感虫水稻品系‘9311’和抗性品系‘BPHR96’为供试材料,观察不同的水源和食物处理(取食‘9311’茎段,取食‘BPHR96’茎段,有水源的饥饿胁迫以及无水源的饥饿胁迫)对褐飞虱死亡率的影响。在玻璃温室内开展水培试验,设置不同浓度营养液培养水稻幼苗,测定幼苗分蘖数、株高、根长、地上部鲜质量和根鲜质量5个表型性状;并观察侵染后褐飞虱的存活数量、增质量率、蜜露排泄量以及寄主选择数量。【结果】无食物的情况下,褐飞虱死亡率上升迅速;无水源饥饿胁迫处理的褐飞虱在接虫后48 h全部死亡;接虫216 h时,有水源饥饿胁迫处理的死亡率达到96.8%,取食‘BPHR96’的死亡率达到85.0%,而取食‘9311’的死亡率也始终维持较低水平(44.3%)。营养液水培试验发现,与对照和高浓度氮磷钾营养液处理相比,低浓度氮磷钾营养液虽然对水稻幼苗的生长有所抑制,但能显著降低褐飞虱的存活数量、增质量率、蜜露排泄量以及寄主选择数量,且抗性水稻品系的效应更为明显。相比于低浓度钾营养液处理,对照和高浓度钾营养液处理能显著促进水稻幼苗的生长,但未发现钾浓度对褐飞虱的取食响应有显著影响。【结论】充足的水分是保证褐飞虱维持生命活动的首要因素,其次才是食物的适口性。低浓度氮磷钾处理能够降低褐飞虱对水稻的危害,高浓度氮磷钾处理则利于褐飞虱的侵害,水稻大田生产过程中可通过水肥管理对褐飞虱进行综合防治。

信号分子硫化氢参与硫肥缓解铝对水稻生长抑制作用的机制

【目的】探究基于施硫肥提高水稻体内硫化氢(H_(2)S)生成缓解水稻在酸性土壤中铝(Al)毒害的栽培方式及其内在机制。【方法】以Al敏感品种Kasalath为试验材料,设置CK,CK+S(硫肥),CK+NaHS(H_(2)S供体),Al,Al+S,Al+NaHS六个盆栽处理,通过测定不同时期水稻体内H_(2)S含量、Al含量、抗氧化系统酶活性,分蘖期根系和光合作用相关指标,明确外源施加硫肥通过调控水稻体内H_(2)S生成缓解Al毒的机制。【结果】与Al处理相比,Al+S处理显著提高水稻体内H_(2)S含量,叶片中的H_(2)S含量在分蘖期和齐穗期分别增加了19.27%和34.99%;根部H_(2)S含量在分蘖期、齐穗期和成熟期分别增加了39.72%、21.08%和30.73%。相比Al处理,Al+S处理显著促进了分蘖期水稻根系的生长,提高了水稻的光合作用能力,同时降低了不同时期水稻根茎叶中的Al含量,在分蘖期分别下降了40.98%、28.47%和24.18%;齐穗期下降了14.58%、50.30%和13.17%;成熟期下降了14.44%、29.78%和8.70%。进一步研究发现,Al+S处理显著增强了水稻体内抗氧化酶(SOD、CAT、APX、POD)的活性,降低了水稻体内过氧化氢(H_(2)O2)、丙二醛(MDA)、超氧阴离子(O_(2)^(-)·)含量,增加了与细胞质Al在液泡中进行分室相关的基因OsALS1以及与修复被Al破坏的细胞壁相关基因OsSTAR1和OsSTAR2的相对表达量。同时,外源施加硫肥还通过调控土壤pH值降低水稻根际土中交换态Al、无机吸附态Al和水溶态Al的含量,增加Al的水合物和氢氧化物的含量。Al+NaHS处理具有同样的效果。【结论】外源增施硫肥能够通过提高水稻体内的H_(2)S含量缓解Al对水稻根系生长和光合作用的抑制,提高抗氧化系统酶活性降低Al对水稻的过氧化损伤,同时促进液泡对水稻细胞质Al的区室化作用,降低细胞壁对Al的吸附或改变土壤中Al的形态,最终降低水稻根系内的Al含量来缓解Al对水稻生长的抑制作用。

低钾胁迫下白菜苗期钾高效品种的筛选及钾效率差异研究

【目的】白菜是典型的喜钾作物,缺钾严重影响其产量。苗期是挖掘钾高效白菜种质资源和耐低钾新品种培育材料鉴定的重要时期,遴选出的指标可以作为钾高效白菜种质资源鉴定和抗逆性研究的科学依据。【方法】以21个白菜自交系品种为试材进行了水培试验。设置适钾(NK,K+6.0 mmol/L)和低钾(LK,K+0.1 mmol/L)处理,连续培养3周后(四叶一心)取样,测定白菜幼苗根系形态、植株长势、钾素含量和积累量等指标。通过主成分分析,筛选影响白菜钾高效利用的重要指标,并利用聚类分析对21份种质进行聚类。【结果】相比适钾处理,低钾处理显著降低了21份白菜幼苗的根系表面积、根系体积、根尖数、地上部钾浓度(SKC)、植株钾浓度(PKC)、地上部钾积累量(SKA)和植株钾积累量(PKA)。所有品种的SKC、PKC、SKA、根系钾积累量(RKA)和PKA这5个指标的耐低钾系数均较低(LPTC<1),而根系钾浓度(RKC)的耐低钾系数较高(LPTC>1)。对参试21份白菜品种进行主成分分析和D值聚类分析,发现3个白菜种质资源属于耐低钾型品种;3个白菜种质资源属于中等耐低钾型品种;13个白菜种质资源属于中等低钾敏感型品种;两个白菜种质资源属于低钾敏感型品种。耐低钾型白菜‘HK42’在适钾和低钾处理下地上部钾运转效率差异不大,而低钾敏感型白菜‘HK40’低钾处理下根系钾运转效率相比适钾处理显著提高58.95%。与‘HK40’品种相比,‘HK42’品种地上部钾利用指数比和钾效率比分别显著降低74.01%和81.70%。【结论】根系干重、地上部钾积累量和植株钾浓度可以作为评价白菜品种耐低钾性强弱的指标。初步确认‘HK27’、‘HK42’和‘HK54’为耐低钾型白菜品种,‘HK40’和‘HK48’为低钾敏感型白菜品种。

黄腐酸钾提高水稻秧苗耐盐性的作用途径分析

【目的】盐胁迫是限制水稻等作物产量品质形成的重要环境因子之一,研发能提高水稻耐盐性风险栽培技术有助于保障我国粮食安全。【方法】以日本晴为材料,于水稻秧苗期进行盐胁迫处理,外源喷施适合浓度的黄腐酸钾(Potassium fulvic acid,PFA),并取样测定干物质量、光合作用、碳水化合物含量、能量物质、钠钾离子浓度及抗氧酶活性等生理指标。【结果】常规种植条件下,黄腐酸钾对水稻秧苗生长发育影响较小,其株高和干物质量与清水(H_(2)O)处理之间的差异未达显著水平,但盐胁迫处理后黄腐酸钾明显提高了水稻秧苗的干物质量和株高。盐胁迫下,黄腐酸钾显著增强水稻秧苗叶片POD和APX活性,降低其相对电导率、过氧化氢及丙二醛含量;另外,黄腐酸钾处理能减轻盐胁迫对叶绿素含量、实际光量子效率、相对电子传递速率和净光合速率的抑制。黄腐酸钾对碳水化合物含量的影响较小,但能减轻盐胁迫对能量代谢的抑制,表现为盐胁迫后水稻叶片非结构性碳水化合物处理间的差异不明显,但黄腐酸钾处理的叶片ATP含量、能荷值以及ATPase活性均显著高于清水处理。相应地,盐胁迫下黄腐酸钾处理的水稻秧苗叶片、茎及根的钠离子浓度显著下降,钾离子浓度则显著上升。【结论】黄腐酸钾可一定程度上提高水稻叶片光合作用,促进ATP的产生及利用,增强抗氧化能力,维持较高的钾离子浓度以及较低的活性氧、钠离子浓度,进而减轻盐胁迫对水稻秧苗的伤害。研究结果可为水稻秧苗耐盐性栽培技术及化学调控物质的研发提供技术及理论支撑。

黄腐酸钾对不同氯盐胁迫下桧柏生长的缓解效应

【目的】探究高浓度氯盐胁迫下桧柏容器苗施加不同质量分数黄腐酸钾(FA-K)后的生长和生理特性,揭示FA-K缓解高浓度氯盐胁迫下桧柏的生理响应机制及差异性,为冬季北方高速公路中央分隔绿化带桧柏的管理维护提供技术支撑。【方法】选取2年生桧柏容器苗开展盆栽试验,以正常生长为对照,设置0.7%NaCl和0.7%CaCl_(2)2种盐分,每种盐分设置0、0.05%、0.10%、0.30%和0.50%5种质量分数FA-K处理,测定各处理下桧柏苗生长指标(苗高生长量、地径生长量、生物量、根冠比)、光合色素含量(叶绿素a、叶绿素b、总叶绿素、类胡萝卜素)、相对电导率、丙二醛含量、渗透调节物质(脯氨酸、可溶性糖)含量、超氧化物歧化酶和过氧化物酶活性。【结果】1)0.7%CaCl_(2)胁迫对桧柏苗生长的抑制作用大于0.7%NaCl胁迫;0.7%CaCl_(2)胁迫下桧柏苗除可溶性糖和类胡萝卜素含量低于NaCl胁迫外,其他生理指标(叶绿素a含量、叶绿素b含量、总叶绿素含量、丙二醛含量、脯氨酸含量、相对电导率、过氧化物酶和超氧化物歧化酶活性)均高于NaCl胁迫;2)2种盐胁迫下,施加FA-K均使桧柏苗苗高生长量、地径生长量、生物量增加,叶绿素a、叶绿素b、总叶绿素、类胡萝卜素含量上升,相对电导率和丙二醛含量下降,超氧化物歧化酶和过氧化物酶活性、脯氨酸和可溶性糖含量呈低-高-低的变化趋势,0.50%FA-K下2种盐胁迫的幼苗生长接近对照;3)相较0.7%NaCl胁迫,FA-K对0.7%CaCl_(2)胁迫表现出更好的缓解作用。【结论】高浓度氯盐胁迫显著抑制桧柏苗生长和存活,0.7%CaCl_(2)抑制作用比0.7%NaCl强;FA-K能够有效缓解NaCl和CaCl_(2)胁迫,0.50%FA-K缓解效果较佳。

入侵杂草喜旱莲子草WRKY转录因子家族鉴定及其除草剂胁迫表达特征

喜旱莲子草(Alternanthera philoxeroides)是我国入侵范围广、入侵程度重的外来入侵杂草,给生态平衡造成严重危害。WRKY是一类植物特有转录因子,在响应除草剂胁迫中发挥重要功能。为系统鉴定并分析喜旱莲子草WRKY家族成员特征,探究其响应除草剂胁迫的诱导表达模式,本研究从该杂草中鉴定到66个WRKY基因,根据系统发育关系将其分为a、b、c 3个亚族,同一亚族成员具有相似的基因结构、保守基序以及蛋白质三级结构。蛋白质特征分析发现,所有ApWRKYs均为亲水性蛋白。表达模式分析发现,ApWRKYs表现时空表达特异性。防效测试表明,5种除草剂均能抑制植物的鲜重和叶绿素含量,其中氯氟比氧乙酸对鲜重抑制率最高,乙羧氟草醚对叶绿素含量抑制率最高;定量分析8个ApWRKYs的除草剂响应模式,发现2个ApWRKYs受草甘膦诱导后表达水平先上升后下降,ApWRKY38.c在施药后7 d内表达量相对稳定;异丙隆和乙羧氟草醚处理0.5~3 d时,3个ApWRKYs表达量呈下降趋势;ApWRKY49.c和ApWRKY53.c分别在氯氟吡氧乙酸和噁草酮处理7 d和3 d时被显著诱导上调表达。这说明ApWRKYs参与喜旱莲子草对除草剂胁迫的响应过程,针对不同的除草剂表现不同的时空诱导表达特征。本研究为进一步探究ApWRKYs响应除草剂胁迫中的生物学功能奠定了基础。

施钾对马铃薯苗期抗旱性的影响

为研究不同施钾水平对马铃薯苗期抗旱性的影响,本研究以马铃薯品种大西洋为材料,对苗期不同干旱胁迫的大西洋增施不同量钾肥,测定其生长指标和生理指标,并探究在不同条件下植株的抗旱性差异。结果表明:干旱胁迫会显著抑制马铃薯株高、茎粗的生长,同时显著降低叶片叶绿素含量、叶片类胡萝卜素含量、光合生理指标及根系活力,会促使马铃薯叶片中丙二醛含量、脯氨酸含量、抗氧化物酶活性增加,进而影响马铃薯块茎的产量及品质。增施一定量的钾肥可有效缓解干旱对上述指标的影响,均在K2(180 kg/hm^(2))水平下效果最佳。在K2施钾水平下,T0、T1和T23种干旱胁迫条件下的马铃薯块茎重量较未施钾肥的分别增加了23.3%、27.8%和36.2%,块茎淀粉含量分别增加了25.2%、25.47%和33.67%,维生素C含量分别增加了34.83%、36.91%和43.05%。综上,施钾量为180 kg/hm 2对马铃薯幼苗抗旱性和生长发育的促进效果最佳。

沟施硫酸钾对桃1 年生枝条抗寒性的影响

【目的】探究沟施不同施用量的钾肥对桃1年生枝条抗寒性的影响,筛选出提高抗寒力的最优钾肥施用量,为林业生产提供科学依据。【方法】以桃品种‘36-5’为试材,以0 g/株施用量为对照,对桃树进行不同钾肥施用量(50、100、150、200、250 g/株)处理,在2022年9月采取沟施处理。于休眠期(2022年11月30日)采1年生枝条样品,进行人工模拟低温处理(0~-30℃处理,以5℃为梯度),测定桃枝条不同温度处理下各钾肥施用量枝条的矿质元素(氮、磷、钾、钙、镁)含量、细胞膜透性(相对电导率、含水量、丙二醛)含量、渗透调节物质(可溶性糖、可溶性蛋白)含量、抗氧化酶系统(过氧化物酶、过氧化氢酶、超氧化物歧化酶活性)、内源激素(脱落酸、生长素、细胞分裂素、赤霉素含量)含量等生理指标,并进行各生理指标的综合评价。【结果】在低温胁迫下,不同钾肥施用量桃枝条抗氧化酶活性增加,增强桃枝条抗氧化酶清除自由基能力,提高渗透调节系统能力,调节细胞膜透性;活性氧自由基产物丙二醛(MDA)降低、相对电导率等膜透性指标降低;渗透调节系统(可溶性蛋白、可溶性糖)含量提高。矿质元素含量增加,脱落酸(ABA)含量增加、ABA/GA比值增加。通过拟合Logistic方程评价得出桃枝条半致死温度,其中150 g/株施用量下桃枝条半致死温度达到最低,为23.22℃。通过隶属函数法综合评价得出,不同钾肥施用量对桃枝条抗寒性由强至弱依次为150>200>250>100>50>0 g(CK)/株。通过对半致死温度与隶属函数进行相关性分析发现二者呈现显著负相关。【结论】半致死温度与隶属函数均可用于抗寒力测定。150 g/株钾肥处理效果最佳,能有效提高桃枝条抗寒性,可为农业生产提供参考。

分蘖期淹水对常规粳稻生长特性、产量形成与钾素吸收的影响

为研究分蘖期淹水胁迫对常规粳稻生长特性、产量、产量构成因子、钾素吸收与钾肥利用率的影响,阐明钾素对常规粳稻分蘖期耐淹性的调控作用,以常规粳稻浙粳99为供试材料开展盆栽试验,设置CK(不淹水,对照)和ST(分蘖期用43 cm水层淹水15 d)2个主处理,在主处理下进一步设置K0(不施钾)和K180(K2O施用量180 kg·hm^(-2))2个钾肥处理。结果显示,相比于对照组,淹水组2个钾肥处理的平均存活率、单位面积有效穗数、单位面积颖花数分别显著(P<0.05)下降16.8百分点、71.1%和68.0%,退水后1 d和成熟期的植株钾素积累量分别显著下降53.8%和44.6%,淹水期间和退水后的钾素积累速率分别显著下降66.7%和45.0%,但植株钾含量、钾肥偏生产力、钾肥回收利用率、钾素收获指数无显著变化。结果表明,分蘖期淹水胁迫显著抑制常规粳稻的正常生长,但在本试验条件下对水稻产量和钾肥利用无显著不利影响,增施钾肥对提高常规粳稻分蘖期的耐淹性有一定的促进作用。