胺鲜酯对高产夏玉米产量及叶片光合羧化酶和保护酶活性的影响

采用田间小区试验,以高产玉米新品种登海661为材料,研究了拔节期叶面喷施10、20和40 mg·L^-1的胺鲜酯（DA-6）对玉米叶片光合羧化酶、保护酶活性和产量的影响.结果表明：喷施胺鲜酯各处理玉米分别比对照（含有表面活性剂和水）增产10.0%(10 mg·L^-1)、8.9%(20 mg·L^-1)和9.4%(40 mg·L^-1),增产效果显著,但各浓度间差异不显著.胺鲜酯处理后,花后玉米的叶面积指数、光合速率、RuBP羧化酶和PEP羧化酶活性均显著上升(P＜0.05),且对光合速率、RuBP羧化酶和PEP羧化酶活性的影响随着处理浓度的增加而提高;与对照相比,胺鲜酯处理后吐丝期、灌浆期、乳熟期和蜡熟期叶片SOD、CAT、POD和GSTs活性及可溶性蛋白质含量显著提高(P＜0.05),MDA含量显著降低(P＜0.05),其中CAT活性随着处理浓度的增加呈上升趋势,其余生理指标各浓度间无显著性差异.     

Foliar application of melatonin delay leaf senescence in maize by improving the antioxidant defense system and enhancing photosynthetic capacity under semi-arid regions

Melatonin is an important plant growth regulator which plays a key role in plant growth and development. The objective of the current research was to evaluate the effect of foliar application of melatonin (MF) on photosynthetic efficiency, antioxidant defense mechanism, and its relation with leaf senescence in maize crop grown in a semi-arid region. A field experiment was conducted during 2017 and 2018 growth season, where melatonin was applied to the foliage at concentrations of 0 (MF₀), 25 (MF₁), 50 (MF₂), and 75 (MF₃) μM at the ninth leaf stage. Foliar application of melatonin significantly improved chlorophyll content, net photosynthetic rate, soluble sugar content, and soluble protein content during the process of leaf senescence. The application of melatonin also enhanced antioxidant enzyme activities including superoxide dismutase, catalase, and peroxidase, while reduced malondialdehyde and reactive oxygen species accumulation. Melatonin foliar application also increased total leaf area per plant, grains per ear, thousand grain weight and grain yield of maize crop in a semi-arid region. The application of melatonin significantly improved photosynthetic activity, antioxidant defense mechanism, and yield of maize crop in a semi-arid region, where the most effective treatment was MF2.

     

植物多糖类复合制剂对大豆光合性能和干物质的影响

大田栽培条件下,在大豆始花期叶面喷施以植物多糖(P1)、植物多糖和5-氨基乙酰丙酸(P2)以及植物多糖、5-氨基乙酰丙酸和缩节胺(P3)为有效成分复配的3种制剂,研究不同植物多糖类复合制剂对大豆叶绿素含量、光合蒸腾特性、干物质积累与分配以及籽粒产量的影响.结果表明:喷施3种制剂35 d内,大豆叶片叶绿素含量与对照相比明显增加,且随生育进程下降的趋势有所延缓;喷施P1和P3使大豆叶片光合速率和水分利用效率分别提高13.2％和10.3％以上.与对照相比,喷施3种制剂促进了大豆地上部于物质积累量的增加、提高了叶片干物质向荚的分配比例,花后干物质同化量对籽粒的贡献率增加17.1％以上;喷施P1和P3后,大豆单株荚数、单株粒数和百粒重显著增加,喷施P2后变化不显著;喷施3种制剂使大豆增产5.9％以上.3种植物多糖类复合制剂可促进大豆叶绿素合成、延缓叶片衰老、改善叶片光合潜能和水分状况,有效调控大豆干物质积累和花后同化物分配,进而实现增产.     

Physiological Strategies to Improve the Performance of Spring Maize (Zea mays L.) Planted under Early and Optimum Sowing Conditions

Low temperature at stand establishment and high temperature at reproductive stage are involved in reduction of grain yield of spring maize. A field study was therefore conducted to evaluate different physiological strategies for improving performance of spring maize under temperature extremes. Seed priming and foliar spray with 3% moringa leaf extract (MLE) and 100 mg L^-1 kinetin solution alone or in all possible combinations with each other at three growth stages (knee height, tasseling and grain filling stage) and hydropriming was compared with control. Seed priming plus foliar spray of MLE and kinetin significantly improved stand establishment especially under early sown crop as indicated by reduced mean emergence time (MET), improved emergence index (EI) and final emergence percentage (FEP). Similarly increased chlorophyll contents, crop growth rate, leaf area index, photosynthetic rate, transpiration rate, relative water content and decreased membrane permeability were recorded in both early and optimum sowing conditions in MLE priming plus foliar spray treatment. All these improvements were harvested in the form of increased yield and harvest index compared with control treatment. Overall crop sown at optimum time performed best but exogenous application of MLE through seed priming and foliar spray maximally improved the performance of early sown maize crop which is attributed more likely due to improved stand establishment, chlorophyll and phenolic contents, increased leaf area duration and grain filling period. It can be concluded that seed priming with MLE along with its foliar spray could increase production of maize under temperature extremes.     

联合固氮菌叶面接种剂的优化及其在玉米叶际的定殖

【背景】联合固氮菌由于不具有宿主专一性,在土壤、叶际中广泛存在,对生态系统氮素供应有着重要贡献,它还可以通过分泌生长激素等间接作用促进植物生长,可作为重要的农业生产菌剂。土壤接种剂由于受土著微生物的竞争和土壤抑菌物质等的影响,接种效果不稳定,难以推广使用。相比于土壤环境,叶际生境相对简单且表面积巨大,进行叶际接种是固氮菌剂推广应用的一个新思路。【目的】优化联合固氮菌菌株W12接种添加剂,制备液体接种剂并研究其在玉米叶际的定殖效果。【方法】对菌株W12进行菌落PCR测序,构建系统发育树并确定分类地位。分别在培养液中添加不同浓度梯度的羧甲基纤维素(Carboxymethyl cellulose,CMC)和甘油(Glycerol,Gly),测量菌株W12生长曲线和固氮酶活性,优化添加剂浓度并制备液体接种剂,对接种剂的有效保存时间进行检测。将接种剂喷洒到玉米叶际,测量其对玉米产量和植株含氮量的影响,并通过低氮培养基进行回收计数。【结果】固氮菌菌株W12的16S r RNA基因序列与变栖克雷伯氏菌(Klebsiella variicola)的相似性高达99%,在培养液中添加CMC和甘油对菌株W12的生长无明显促进和抑制效果,但均提高了固氮酶活性。添加甘油制备的接种剂在盆栽和大田玉米叶面喷施后,在玉米生长末期叶际回收到的W12类似菌分别为4.3×105 CFU/g叶片和1.7×105 CFU/g叶片,显著高于未接种的处理;而且大田玉米籽粒、茎部和叶片的含氮量高于不接种的对照处理。经过90 d贮藏后,4°C保存的接种剂剩余活菌数均高于1.0×108 CFU/m L。【结论】羧甲基纤维素和甘油的添加不仅有利于固氮菌液体接种剂在叶片的附着,并能显著提高联合固氮菌菌株W12的固氮酶活性,低温冷藏可保证液体接种剂的有效活菌数;液体接种剂在玉米叶际喷施后,菌株W12能够成功定殖,并显著提高玉米植株和籽粒含氮量。研究结果为固氮菌叶面接种剂的制备和应用,以及实现农业氮肥减施保产的目标提供了借鉴意义。     

Zn application through seed priming improves productivity and grain nutritional quality of silage corn

The micronutrient application in agriculture takes place through soil application, foliar spraying or added as seed treatments. The latter method, the nutri-priming, is an appealing option due to the easiness in handling it, environment-friendly, cost effectiveness and efficient against multiple environmental stressors. To assess the feasibility of Zn-priming technique on seeds germination, two experiments were conducted and assessed the efficiency on the growth rate, yield and biofortification on the forage maize (Zea mays L.). The first laboratory experiment assessed the effect of Zn-priming for three-time exposures (i.e., 8, 16 and 24 h) on germination parameters. The second experiment was done in a greenhouse, by using the 10 seeds obtained from 24 h priming. Five seed pretreatments were studied (0, 0.1, 0.5, 1 and 11 2 % of zinc sulfate heptahydrate (ZnSO₄·7H₂O)) compared to the recommended dose (5 ppm of Zn at 5–9 leaf stage) provided by soil application. The obtained results revealed that all seed priming, including hydro-priming, improve seed germination performance. Zn-priming increased the grain yield and helped to enrich the seeds in this element, especially seedlings treated with 0.5 % Zn sulphate for 24 h leading to an increase in yield by 47 % and in Zn content by 15 %. The comparison of the results from both techniques showed that Zn-priming could be was very effective than the traditional direct application in soil.     

幼穗分化期喷施磷钾肥对早稻抵御低温及产量和生理特性的影响

以超级杂交早稻品种淦鑫203为材料,以叶面喷清水为对照(CK),设置0.1%(P1)、0.3%(P3)和0.5%(P5)3个浓度的磷酸二氢钾以及撒施草木灰(MH)处理,研究了双季早稻幼穗分化期遭遇低温条件下喷施磷钾肥对水稻叶温、产量和生理特性的影响.结果表明: 低温期间6:00—18:00所有时间段,喷施磷酸二氢钾和草木灰的稻株叶片温度均高于CK;低温胁迫下各处理稻株叶片叶绿素含量和净光合速率均逐渐降低,以P3处理降低幅度最小;各处理抗氧化酶活性产生不同程度的变化,P3处理的超氧化物歧化酶(SOD)、过氧化物酶(POD)活性上升幅度均高于其余处理,而过氧化氢酶(CAT)活性降低幅度低于其余处理;低温处理结束后,以CK处理的丙二醛(MDA)含量最高;低温胁迫下喷施磷酸二氢钾和草木灰处理均能不同程度提高植株干物质积累,达到减缓产量降低的效果,其中以P3处理最佳;从产量结构上看,各处理较CK每穗总粒数、结实率、千粒重均有明显改善.叶面喷施0.3%磷酸二氢钾是增强双季超级杂交早稻幼穗分化期低温抵御能力的较为实用的农艺措施.     

Effects of nitrogen spraying on the post-anthesis stage of winter wheat under waterlogging stress

Waterlogging is a main stress factor during the late growing stage of winter wheat (Triticum aestivum L.) in the southern Huanghuai and Yangtze Valley regions of China. The effects of nitrogen spraying on post-anthesis of winter wheat under waterlogging stress were studied in continuous growing seasons from 2009 to 2011. The results showed that waterlogging after the anthesis stage significantly reduced root respiratory activity, leaf greenness (SPAD reading), photosynthetic rate (P _n), stomatal conductance (G _s) and transpiration rate (T _r) by averages of 11.09, 10.75, 15.18, 8.97 and 8.82 %, respectively, increased intercellular CO₂ concentration (C _i) by 9.74 % and decreased grain number per spike, 1,000-grain weight and grain yield by 8.07, 12.68 and 20.11 %, respectively. Nitrogen spraying significantly improved root respiratory activity, leaf greenness (SPAD reading), photosynthetic rate (P _n), stomatal conductance (G _s) and transpiration rate (T _r) by 4.96, 7.35, 7.01, 5.09 and 5.09 %, respectively, reduced intercellular CO₂ concentration (C _i) by 9.74 % and increased grain number per spike, 1,000-grain weight and grain yield by 4.71, 6.45 and 11.48 %, respectively. However, neither nitrogen spraying nor waterlogging had significant effects on spike number. There was significant interaction between waterlogging and nitrogen spraying. Our results suggest that nitrogen spraying is an effective way to alleviate the negative effects of waterlogging stress after anthesis stage in winter wheat.     

Compensating effect of fulvic acid and super-absorbent polymer on leaf gas exchange and water use efficiency of maize under moderate water deficit conditions

A field-based pot experiment with maize plants was conducted to examine the effect of combined fulvic acid (FA) and super-absorbent polymer (SAP) on leaf gas exchange, water use efficiency, and grain yield under soil water deficit. SAP (45 kg hm^?2) was applied to the topsoil at sowing. Plants were well-watered (80% field capacity), but subjected to water deficit (50% field capacity) from tassel stage to grain-fill. FA solution (2 g L^?1) was sprayed onto plant leaves at 2 and 9 days after imposing water deficit. Under water deficit, SAP and FA application did not affect evapotranspiration, but increased leaf abscisic acid and decreased leaf transpiration rate with a little change in photosynthesis, thus improving instantaneous water use efficiency. Applying SAP and FA under water deficit also increased grain yield by 19% and grain water use efficiency by 24%, largely attributed to an increase in kernel number. In contrast, under well-watered condition the two chemicals increased stomatal conductance, leaf transpiration, photosynthesis and chlorophyll content, but did not change kernel number and were relatively less effective in respect to water use efficiency compared to water-stressed condition. This study showed that application of foliar FA and soil SAP had little effect on evapotranspiration but maintained high photosynthesis and kernel number, and improved water use efficiency under soil water deficit.     

Epibrassinolide Application Regulates Some Key Physio-biochemical Attributes As Well As Oxidative Defense System in Maize Plants Grown Under Saline Stress

It was aimed to investigate the ameliorative effect of exogenously applied 24-epibrassinolide (EBR) on some key growth parameters and mineral elements in two salt-stressed maize (PR 32T83 and PR 34N24) cultivars. A factorial experiment was designed with two electrical permeability (EC) levels (1.1 and 8.0 dS/m) and two levels (1.5 and 2.0 µM) of EBR supplied as a seed treatment, foliar spray, or both in combination. The foliar application of EBR was done once a week during the experiment. After 42 days of these treatments, the plants were harvested to assess growth, water relations, and oxidative and antioxidative systems. Salt stress markedly reduced plant fresh and dry weights, maximum fluorescence yield of PS-II, chlorophyll contents, leaf water potential, and leaf K and Ca, but it increased membrane permeability, the activities of superoxide dismutase (SOD; EC 1.15.1.1), peroxidase (POD; EC. 1.11.1.7), and catalase (CAT; EC. 1.11.1.6) enzymes, and the contents of proline and glycine betaine, leaf sap osmotic pressure, lipid peroxidation, hydrogen peroxide, and leaf Na and Cl. However, both seed treatment and foliar application of EBR to the maize plants exposed to saline conditions enhanced key growth attributes, water relations, and the activities of various antioxidant enzymes as well as the levels of proline, but they reduced electrolyte leakage, and H₂O₂ and MDA contents. Saline stress reduced leaf N, Ca²⁺, K⁺, and P contents as compared to those in the non-stressed plants. Both seed treatment and foliar application of EBR reduced Na⁺ and Cl^? concentrations, but increased those of N, Ca²⁺, K⁺, and P. Foliar application of EBR was more effective in increasing nutrient levels of plants grown at the high saline regime compared to the seed treatment of EBR. The study clearly indicates that both seed treatment and foliar application of EBR at the rate of 2.0 µM can overcome the detrimental effect of salinity stress on maize growth, which was found to be significantly linked to reduced concentrations of Na, Cl, MDA, and H₂O₂ as well as EL and increased activities of key antioxidant enzymes in the maize plants.     

Effects of foliar application of BAP on source and sink strength in four six-rowed barley (Hordeum vulgare L.) cultivars

A field experiment was conducted to investigate the effects of foliar application of a synthetic cytokinin (BAP) on source and sink strength of four different six-rowed barley (Hordeum vulgare L.) cultivars. Different spraying treatments consisting of spraying on whole plant, spraying only on leaves and spraying only on ears started at anthesis and continued for 7 days. One additional spraying was carried out on late period of grain filling. Results showed that spraying only on leaves did not affect ear weight, grain yield and 1,000-grain weight, while the two other treatments increased all above mentioned traits. Neither of treatments affected stem weight, biological yield and contribution of stem reserves in grain filling. Exogenous cytokinin did not increase photosynthetic rate and chlorophyll content in treated leaves until late period of grain filling, although there was no significant increase in final grain weight due to late application of BAP. Our results suggested that effects of foliar application of BAP were mostly due to increased sink size soon after anthesis and increased sink demand probably met by current photosynthesis of organs other than leaves, like ear green tissues. An erratum to this article is available at .     

Isozymes as Genetic Markers in Maize Breeding

The major objective of the research is to identify and locate quantitative trait loci (QTL_s) in the Yugoslav maize population. The plants (F2) were selected for the analysis at seedling stage and were selfed to obtain F3 generation. The analysis covered about 15 enzymes controlled by about 30 loci. The seeds of F3 family planted in the greenhouse for measuring some quantitative traits, recorded tasselling and silking during vegetation. At the end of vegetation grain yield, and some other quantitative traits of grain in F3 family were assessed. The relationship between marker loci and the loci for quantitative traits (QTL_s) were estimated by computerized statistical method.     

Combined effects of selenium and drought on photosynthesis and mitochondrial respiration in potato.

The possible effects of selenium (Se) foliar spraying and drought were studied for 3 months in potato (Solanum tuberosum L.) cultivar Desiree in Ljubljana, Slovenia. Four combinations of treatments were conducted: well-watered plants with and without Se foliar spraying, and drought exposed plants with and without Se foliar spraying. The following parameters were monitored 2 and 4 weeks after treatments: net photosynthesis, transpiration rate, quantum yield of photosystem II (PSII), and respiratory potential measured by electron transport system activity. After 3 months of treatments, leaf water potential and tuber yield were determined. The content of Se in tubers was measured after harvesting time. Several effects of drought and Se foliar spraying and their combinations were found. Net photosynthesis and respiratory potential were lower in drought exposed plants 4 weeks after treatments. Se induced higher respiratory potential in the leaves 4 weeks after treatments. Higher efficiency of energy conversion in PSII, expressed by a higher effective quantum yield, was observed in Se treated plants 2 weeks after treatments. Foliarly applied Se was efficiently absorbed by plant leaves and transported to the tubers.     

Effectiveness of potassium sulfate in mitigating salt-induced adverse effects on different physio-biochemical attributes in sunflower (Helianthus annuus L.)

To assess whether foliar application of K+S as potassium sulfate (K₂SO₄) could alleviate the adverse effects of salt on sunflower (Helianthus annuus L. cv. SF-187) plants, a greenhouse experiment was conducted. There were two NaCl levels (0 and 150 mM) applied to the growth medium and six levels of K+S as K₂SO₄ (NS (no spray), WS (spray of water+0.1% Tween 20 solution), 0.5% K+0.21% S, 1.0% K+0.41% S, 1.5% K+0.62% S, and 2.0% K+0.82% S in 0.1% Tween-20 solution) applied two times foliarly to non-stressed and salt-stressed sunflower plants. Salt stress markedly repressed the growth, yield, photosynthetic pigments, water relations and photosynthetic attributes, quantum yield (F_v/F_m), leaf and root K⁺, Mg²⁺, P, Ca²⁺, N as well as K⁺/Na⁺ ratios, while it enhanced the cell membrane permeability, and leaf and root Na⁺ and Cl⁻ concentrations. Foliar application of potassium sulfate significantly improved growth, achene yield, photosynthetic and transpiration rates, stomatal conductance, water use efficiency, leaf turgor and enhanced shoot and leaf K⁺ of the salt-stressed sunflower plants, but it did not improve leaf and root Na⁺, Cl⁻, Mg²⁺, P, Ca²⁺, N as well as K⁺/Na⁺ ratios. The most effective dose of K+S for improving growth and achene yield was found to be 1.5% K+0.62% S and 1% K+0.41% S, respectively. Improvement in growth of sunflower plants due to exogenously applied K₂SO₄ was found to be linked to enhanced photosynthetic capacity, water use efficiency, leaf turgor and relative water content.     

玉米品种耐阴性指标的筛选与评价

采用大田试验,研究了24个玉米品种在50%遮光处理下的形态、生理与产量性状的变化.结果表明：与自然光照相比,遮光处理后,玉米的株高降低,茎粗减小,雌雄间隔期延长,净光合速率减小,比叶重减小,地上部干物质量减少,果穗缩短变细,穗轴直径减小,行粒数减少,籽粒产量显著降低,其中雌雄间隔期、净光合速率、比叶重和行粒数变化的百分率与地上部干物质量和籽粒产量减少的百分率之间呈显著或极显著相关,可作为田间鉴定玉米耐阴性的有效指标.采用综合耐阴性状作为评价参数,经聚类分析表明,郑单958、浚单20、登海602等14个品种属耐阴型品种,安玉12、豫玉22等10个品种属非耐阴型品种.表明以形态、生理指标结合产量性状来评价玉米耐阴性较为客观,且简单易行.     

植物多糖类复合制剂对冬小麦产量及物质转运的影响

在大田栽培条件下,采用生物质多糖(P₁)、生物质多糖和5 氨基乙酰丙酸复配(P₂),以及生物质多糖、5-氨基乙酰丙酸和缩节胺为有效成分复配(P₃)的3种不同制剂,研究在冬小麦始花期叶面喷施制剂对其产量构成、蔗糖、可溶性总糖、干物质贮运以及氮磷养分累积与转移的影响.结果表明: 喷施3种制剂使冬小麦穗粒数和千粒重增加,增产8.5%以上;喷施20 d内,小麦旗叶蔗糖含量较对照明显增加;喷施P₁和P₃使小麦籽粒可溶性糖含量分别比对照增加4.5%和11.0%.P₃增加了小麦花后干物质及氮磷养分累积量,分别较对照增加48.5%、116.9%和18.1%,P₃还显著提高了小麦花后干物质及养分累积对产量的贡献,但花前养分向籽粒转移对产量的贡献小于其他处理.小麦增产与植物多糖类复合制剂有效调控营养器官光合产物输出、籽粒可溶性糖积累,以及促进花后干物质和氮磷养分累积有关.     

Relationship between Photosynthesis and Protein Synthesis in Maize: II. Interconversions of the Photoassimilated Carbon in the Ear Leaf and in the Intermediary Organs to Synthesize the Seed Storage Proteins and Starch

The mechanisms priming the production, the movement, and the transient and final storage of the photoassimilated carbon in the maize plant were examined at the metabolic level during the formation of the seed, with the ultimate aim to identify metabolic steps restricting grain yield and explaining the delay of formation of the reserve molecules. Under normal field conditions, we show that maize directly supplies the developing seed with the photoassimilated carbon which undergoes numerous interconversions from the ear leaf to the grain. The proteins, either in the leaf or in the seed, are primarily synthesized from incoming amino acids. Nevertheless, a secondary in situ synthesis of amino acids provides the proteins with new amino acids. The amino acids of this second set, slowly synthesized in the seed from the photosynthetic carbon skeletons, are not detected in their free form but immediately and regularly incorporated into the seed proteins, in such a way that, after 4 days of chase, the proportion of the radioactive labeling of the amino acids of the different storage protein groups corresponds to their amino acid composition. In the leaf, the labeling of proteins also arises from different metabolisms, but mainly from the photosynthetic metabolism. Contrary to the seed proteins, the time course of the labeled leaf proteins implies a rapid turnover. The second labeling of starch and proteins in the ear leaf involves a reassimilation of CO₂, a process optimizing the carbon uptake in maize.     

Exogenously applied polyamines increase drought tolerance of rice by improving leaf water status,photosynthesis and membrane properties

Drought stress hampers rice performance principally by disrupting the plant–water relations and structure of biological membranes. This study appraised the role of polyamines (PAs) in improving drought tolerance in fine grain aromatic rice (Oryza sativa L.). Three PAs [putrescine (Put), spermidine (Spd) and spermine (Spm)] were used each at 10 μM as seed priming (by soaking seeds in solution) and foliar spray. Primed and non-primed seeds were sown in plastic pots with normal irrigation in a phytotron. At four-leaf stage, plants were subjected to drought stress by bringing the soil moisture down to 50% of field capacity by halting water supply. For foliar application, 10 μM solutions each of Put, Spd and Spm were sprayed at five-leaf stage. Results revealed that drought stress severely reduced the rice fresh and dry weights, while PAs application improved net photosynthesis, water use efficiency, leaf water status, production of free proline, anthocyanins and soluble phenolics and improved membrane properties. PAs improved drought tolerance in terms of dry matter yield and net photosynthesis was associated with the maintenance of leaf water status and improved water use efficiency. Among the antioxidants, catalase activity was negatively related to H₂O₂ and membrane permeability, which indicated alleviation of oxidative damage on cellular membranes by PAs application. Foliar application was more effective than the seed priming, and among the PAs, Spm was the most effective in improving drought tolerance.     

Effect of the change of leaf angle arrangement on productivity of maize (Zea mays L.) stands

Leaf angles, frequency distribution of leaf area inclinations, leaf area index, amount of intercepted radiation, biological, vegetative and grain yields and grain yield proportion of biological yield were determined in maize stands of two population densities, 55 555 plants ha^?1 (S ₁), and 80 000 plants ha^?1 (S ₂). Also the effect of the artificial change of leaf angle upon these indices was studied. We classified normal maize stand (N) as the interstage between a planophile and a plagiophile type of canopy, that with artificially changed leaf angle (V) as an erectophile type of canopy. The relative interception of the incoming radiation in the variantsV S ₁ andV S ₂ was lower than in the variantsN S ₁ andN S ₂. The variantsV in comparison with variants N increased grain yield and biological yield.     

Nutritional, growth, and reproductive responses of maize (Zea mays L.) to arbuscular mycorrhizal inoculation during and after drought stress at tasselling

The effects of root colonization by the arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck & Smith on nutritional, growth, and reproductive attributes of two tropical maize cultivars with different sensitivities to drought were studied. Freshly regenerated seeds of selection cycles 0 (cv. C0, drought-sensitive) and 8 (cv. C8, drought-resistant) of the lowland tropical maize population "Tuxpeño sequía" were used in this greenhouse experiment. Maize plants were subjected to drought stress for 3 weeks following tasselling (75–95 days after sowing) and rewatered for the subsequent 5 weeks until harvest. Mycorrhizal (M+) plants had significantly higher uptake of N, P, K, Mg, Mn, and Zn into grain than non-mycorrhizal (M–) plants under drought conditions. AM inoculation also produced significantly greater shoot masses in C0 and C8 regardless of the drought-stress treatment. In the sensitive cultivar C0, drought stress reduced the shoot mass and grain yield by 23% and 55%, respectively, when roots were not colonized, while the reductions were only 12% and 31%, respectively, with mycorrhizal association. In addition, the emergence of tassels and silks was earlier in M+ plants than in M– plants under drought conditions. Mycorrhizal response was more pronounced under both well-watered and drought conditions in C0 than in the C8 cultivar. The overall results suggest that AM inoculation affects host plant nutritional status and growth and thereby alters the reproductive behaviour of maize under drought conditions.