Ear Leaf Research Articles

Silicon in the morphometry and germination of corn seeds for silage

As a forage, the objective of this study was to evaluate corn plant, seed development and seed germination in response to silicon application at different doses pathway leaf. The experimental design was randomized blocks with four treatments of different doses of silicon, equivalent to 0.0, 100.0, 200.0 and 300.0kg ha-1 of calcium silicate, at 22%, and four replications, applied pathway leaf. It was observed that the applied silicon did not influence any of the plant morphometric variables, however it altered the ear characteristics regarding weight and diameter, at which the best response was observed in the application equivalent to 100kg silicate-1 ha-1. The applied silicon doses showed no significant differences in morphological characteristics such as plant height, first ear height, stem diameter, number, and leaf angles. Significant differences were found in the weight of one thousand grains, and by increasing the silicon dose, there was an increase in the weight of one thousand grains and in the germination; in 7 days, it was found a decrease in germination percentage as well as in the percentage of normal seedlings when increasing the calcium silicate doses. It was concluded that the application of calcium silicate via leaf increased the stem diameter, the ear of corn and the weight of one thousand seeds and decreased the germination percentage in seven days and the appearance of normal seedling.

A novel plant growth regulator improves the grain yield of high-density maize crops by reducing stalk lodging and promoting a compact plant type

• DHEAP is a novel plant growth regulator. • DHEAP improved maize lodging resistance. • DHEAP shaped a compact maize plant type. • DHEAP is helpful to increases summer maize planting density in NCP. Increasing the planting density (PD) of maize ( Zea mays L.) crops is the most efficient method for enhancing maize grain yield, but supra-optimum PD leads to an increase in lodged maize, which alters the maize canopy structure. In this study, N, N-Diethyl-2-hexanoyl oxygen radicals-ethyl amine (2-ethyl chloride) phosphonic acid salt (DHEAP, a single compound), a novel plant growth regulator, was sprayed at the seven-expanded-leaf stage under two different PDs (75,000, and 90,000 plants ha -1 ) using two maize hybrids, ZD958 (lodging-resistance) and XY335 (lodging-susceptible), to reduce maize lodging rates and improve the maize canopy structure under high PD. After DHEAP treatment, the maize lodging rate of ZD958 and XY335 decreased by 70.87% and 75.22%, respectively, through a change in the morphological structure (i.e., reduced plant and ear heights and increased mean tilt angle) and an improvement in the basal internode quality (i.e., increased diameter, dry weight per unit length, crushing strength, cellulose content, lignin content, and vascular area, and reduced length). In addition, DHEAP treatment significantly reduced gibberellin (GA 3 ) contents in maize basal internodes. Moreover, the increase in the mean tilt angle (MTA) above the maize ear leaf after DHEAP treatment improved the light penetration in the middle leaf strata, which increased the chlorophyll content (SPAD), net photosynthetic rate (P n ), and Rubisco enzyme activities. Finally, DHEAP treatment increased the grain yield of ZD958 and XY335 under 90,000 PD by 22.28% and 43.14%, respectively. Thus, it was concluded that the spraying of DHEAP effectively reduced maize lodging rates and improved the photosynthetic performance of the maize ear leaf, which increased maize grain yield under high PDs.

Comparison of aerial and ground sprayer fungicide application technologies on canopy coverage, disease severity, lodging, and yield of corn

Fungicides may be applied to corn using an airplane or a ground sprayer. Questions regarding which technology is better at coverage throughout the corn canopy are common among farmers and agronomists. The objectives of this study were to compare the efficacy of three application technologies in terms of canopy coverage, foliar disease management, lodging and yield response. A fungicide was applied to corn at silking (R1) by airplane, a traditional ground sprayer with an overhead spray boom, or a ground sprayer with 360 Undercover sprayers that hang down into the canopy. Replicated on-farm and small-plot trials were conducted across Iowa in 2017 and 2018 for a total of nine site-years. Fungicide coverage was measured as ppm of pyrenetetrasulfonic acid (PTSA) dye detected on corn leaves, percent coverage of water sensitive spray cards, and percent of total application received. Foliar disease data were collected in three zones of the canopy: the upper canopy (UC), the ear leaf (EL), and the lower canopy (LC). Coverage and disease severity were not correlated with yield. In the 2017 on-farm trials, all three application methods delivered similar fungicide coverage on the EL and LC. In 2018, traditional and undercover methods provided greater coverage when compared to aerial application, however, fungicide distribution within the canopy was similar among the application methods. Overall trends indicated the traditional spray method delivered the best coverage to the UC. The aerial spray method delivered the least coverage to the EL and LC for three site-years. The undercover spray method resulted in greater coverage to the LC. Foliar fungicides applied by all three application methods significantly reduced foliar disease severity, and fungicide application methods did not differ from each other, and reduced disease severity to similar levels. Lodging was reduced approximately 50–75% by all application methods. For 8 of 9 site years, fungicide application did not affect yield significantly (P > 0.05), although numerically less yield was consistently recorded in the non-sprayed controls. Our findings indicate these three application technologies were similarly effective in reducing plant disease levels and lodging. But the reduction in disease due to fungicide application did not affect corn yield.

Heterogeneous Light Conditions Reduce the Assimilate Translocation Towards Maize Ears.

The border row crop in strip intercropped maize is often exposed to heterogeneous light conditions, resulting in increased photosynthesis and yield decreased. Previous studies have focused on photosynthetic productivity, whereas carbon allocation could also be one of the major causes of decreased yield. However, carbon distribution remains unclear in partially shaded conditions. In the present study, we applied heterogeneous light conditions (T), and one side of plants was shaded (T-30%), keeping the other side fully exposed to light (T-100%), as compared to control plants that were exposed entirely to full-light (CK). Dry weight, carbon assimilation, 13C abundance, and transport tissue structure were analyzed to clarify the carbon distribution in partial shading of plants. T caused a marked decline in dry weight and harvest index (HI), whereas dry weight in unshaded and shaded leaves did not differ. Net photosynthesis rate (Pn), the activity of sucrose phosphate synthase enzymes (SPS), and sucrose concentration increased in unshaded leaves. Appropriately, 5.7% of the 13C from unshaded leaves was transferred to shaded leaves. Furthermore, plasmodesma density in the unshaded (T-100%) and shaded (T-30%) leaves in T was not significantly different but was lower than that of CK. Similarly, the vascular bundle total area of T was decreased. 13C transfer from unshaded leaves to ear in T was decreased by 18.0% compared with that in CK. Moreover, 13C and sucrose concentration of stem in T were higher than those in CK. Our results suggested that, under heterogeneous light, shaded leaves as a sink imported the carbohydrates from the unshaded leaves. Ear and shaded leaf competed for carbohydrates, and were not conducive to tissue structure of sucrose transport, resulting in a decrease in the carbon proportion in the ear, harvest index, and ear weight.

Effect of reduced spacing on relationship of physiological, morphological and productive traits of corn yield

Increasing corn grain production without devastating new forest areas is a viable alternative to controlling deforestation. However, increasing plant density in the area may alter plant morphophysiological and productive traits. The objective of this study was to characterize relationships between physiological, morphological and yield traits of corn plants, as well as the cause, effect and relationship of the traits on grain yield. The experiment was carried out in randomized complete block design with four replications. The corn hybrids (2B655PW, AG7088PRO3 and P4285YHR) were grown with row spacing of 40 cm, 60 cm, 80 cm, 95 cm. The evaluated traits physiological were: net photosynthesis (PN), stomatal conductance (Gs), intercellular concentration of CO2 (Ci), leaf transpiration (E), water use efficiency (WUE) and carboxylation efficiency (CE). The morphological were: plant height (PH) and ear insertion height (EIH), stem diameter (SD), and leaf area (LA) and the productive traits were the total number of ear per hectare (NE), number of grains per ear (NGE), grain mass per ear (GME), 100 grain weight (100GW) and grain yield (GY). The characteristics of maize hybrids cultivated in environment with reduced spacing (40cm, 60cm, 80cm, 95cm) of the 2016/2017 crop were investigated through the multicollinearity path analysis. The physiological, morphological and productive traits are considered sources of variation of cause and effect of corn yield in reduced spaced. This traits are essential for observations in maize breeding programs to obtain high yielding varieties in reduced spacing. In conclusion, the physiological (PN, CE, WUE, Ci, Gs), morphological (EIH, SD, LA) and productive (NE, GME) traits provide gains in maize grain yield via indirect selection when the crop is subjected to 40 cm row spacing.

Response of Watermelon Pulp (Citrullus colocynthoides) to Intercropped Maize (Zea mays L.) With Plants Distributions Under Different Nitrogen Fertilization Levels

Two field experiments were carried out at the Experimental Farm of Gemmeiza Agriculture Research Station, Agricultural Research Center (ARC), Egypt after 2018 and 2019 summer growing seasons to determine the effect of intercropping pattern of yellow maize hybrid (single cross 168: “SC 168”) with watermelon pulp at three plant distributions (20 cm between hills and one plant/hill, 40 cm between hills and two plants/hill and 60 cm between hills and three plants/hill) and different levels of nitrogen fertilizer (25, 50, 75 and 100% of the recommended dose “120 kg N fad-1”) as well as their interactions on maize and watermelon pulp growth, yield and its attributes as well as competitive relationships and yield advantages. The experiments were carried out in split-plot design with four replicates. The main-plots were assigned to plant distributions of maize, the sub-plots were allocated to levels of nitrogen fertilizer for maize. The obtained results showed that planting maize plants on one side of terraces of 140 cm width with 20 cm between hills and leaving one plant/hill and planting watermelon pulp on the other side of the terraces produced the highest values of plant height, ear height, number of kernels row-1, 100-kernel weight and grain yield fad-1, at the same time the lowest values of ear leaf area, ear length, ear diameter and number of rows ear-1 of maize as well as the lowest values of growth, yield and its attributes of watermelon pulp during the both seasons. Mineral fertilizing maize plants with 75% of the recommended dose (90 kg N/fad) and watermelon pulp with the recommended dose produced the highest values of all studied growth characters, yield and its attributes of maize and watermelon pulp in both seasons. The highest values of land equivalent ratio (LER), relative crowding coefficient (RCC), area time equivalent ratio (ATER), land equivalent coefficient (LEC), aggressivity index (AI), monetary advantage index (MAI), actual yield (L.E.) of watermelon, Total income (L.E.) and economic return (L.E.) were obtained from planting maize plants on one side of terraces of 140 cm width with 60 cm between hills and leaving three plants/hill and planting watermelon pulp on the other side of the terraces besides fertilizing maize plants with 75% of the recommended dose (90 kg N/fad) and watermelon pulp with the recommended dose in both seasons. It can be recommended that planting maize on 60 cm between hills and leaving three plants/hill and planting watermelon pulp on the other side of the terraces besides fertilizing maize plants with 90 kg N/fad and watermelon pulp with the recommended dose to obtain the maximum values growth, yield and its attributes of watermelon pulp and competitive relationships and yield advantages of both crops under the climates conditions of Middle Delta, Egypt.

Effect of humic acid organic fertilizer on growth and yield of sticky maize (Zea mays) in Central Vietnam

The aim of this study was to investigate the effects of application of humic acid organic fertilizer (Hop Tri Super Humic - 95.0%) on the growth and yield of sticky maize plants. Field experiment was conducted in spring summer season of 2019 in Central Vietnam. Four different doses of the fertilizer (0, 2, 4. 6 kg/ha) were applied to the soil. Growing time, plant height, ear length, number of leaves per plant, ear leaf area, ear size, yield and its components were investigated. The results indicated that application of Hop Tri Super Humic fertilizer had a positive effect on all the mentioned parameters across the fertilizer levels. The highest yield of 6.95 t/ha was obtained under 4 kg humic acid organic fertilizer treatment. Based on this outcome, use of Hop Tri Super Humic organic fertilizer @ 4 kg/ha was found an optimal dose as a nutrient supplement for obtaining higher growth and yield of sticky maize grown in Central Vietnam.

Effect of municipal wastewater irrigation and well water on plant and soil characteristics

In order to investigate the effect of treated wastewater on forage yield, nutrient elements and heavy metals in corn plants (Zea maize, 704 single cross), a field experiment was conducted in RCBD with three treatments in four replications in 2017. Irrigation with well water as first treatment, irrigation with wastewater as second treatment and irrigation with well water and wastewater was alternately applied as a third treatment. The results showed that the highest amount of forage corn yield, stalk and ear dry weight, plant height and leaf number and spade index were obtained in irrigation with wastewater. The highest nitrogen content of leaf and stalk and corn grain was obtained in irrigation with wastewater treatment and the least amount in irrigation with well water treatment was obtained. The amount of phosphorus and potassium measured in leaf and stalk of corn in all three treatments were not significantly different. Also, the highest amount of iron and zinc in leaf and stalk of corn was obtained in irrigation with wastewater treatment. The results showed that the amount of heavy metals including lead, cadmium and nickel in soils were not significantly different in all three treatments. According to the results, the use of urban wastewater not only does not cause soil and plant pollution to heavy elements, but also increases plant yield and nutrition.

In Vitro Anthelmintic Activity of Acalypha Indica Leaves Extracts

Anting-anting leaves (Acalypha indica L) is one of the wild plants (weeds) that are often used by the community to treat helminthic diseases such as ascariasis, containing several potentially anthelmintic compounds, namely saponins, tannins and flavonoids. The purpose of this study was to determine the effect of giving Anting-anting leaf extract (Acalypha indica L) as an anthelmintic to the time of death of pork roundworms (Ascaris suum Goeze). The method in this study was pre-experimental with a post test only group design. The subjects of the study were Ascaris suum. The study was conducted at the Parasitology Laboratory of the Surabaya Polytechnic Health Medical Laboratory Technologist Department in December-May 2018. This study used 5 treatment groups, 0.9% NaCl as negative control and 0.25% pirantel pamoate as positive control and 60%, 80% and 100%. Data were analyzed using the Kolmogrov-Smirnov test, then the Kruskal-Wallis test was then continued using a Post-Hoc test to determine the difference in anthelmintic power of ear leaf extract of each concentration with positive control over the time of worm death. The average time of Ascaris suum worm death at a concentration of a concentration of 60% for 228.5 minutes, a concentration of 80% for 174 minutes, and a concentration of 100% for 92 minutes. So it can be concluded that the leaf extract of Acalypha L has an anthelmintic effect on the Ascaris suum worm.
 
 Keywords: anthelmintic; Ascaris suum; anting-anting leaf

干旱胁迫对玉米叶片光合特性和穗发育特征的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 干旱胁迫对玉米叶片光合特性和穗发育特征的影响 DOI: 10.5846/stxb201811022371 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 作物生物学国家重点实验室开放课题（2019KF03）；农业部商丘农业环境科学观测实验站开放课题（FIRI2019-02-0103）；国家"十三五国家重点研发计划"（2016YFD0100503） Effects of drought on photosynthesis and ear development characteristics of maize Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:玉米是需水量较大的粮食作物之一，拔节至开花的穗期是其一生中的需水临界期，研究玉米穗期对干旱胁迫的响应机制对提高玉米干旱适应性具有重要意义。以筛选后的干旱敏感自交系PH6WC （6WC）和抗旱自交系郑58（Z58）为试验材料，采用测坑控水试验，于穗期设置3个水分处理（正常灌水CK、轻度干旱LD、中度干旱MD），研究了穗期不同水分处理对雌雄穗发育特性、开花吐丝间隔以及穗位叶光合特性的影响。结果表明：LD对Z58的株高、雄穗生长特性、叶绿素相对含量和光系统II最大光化学效率没有显著影响，但雌穗长显著降低；MD显著降低了Z58的穗位叶光合特性、雌雄穗的穗长和干物质积累。对于6WC，LD抑制了其植株生长和穗的发育，使雌穗长、雌穗直径、雄穗长、干物质向穗的分配比率、穗位叶的叶绿素a、叶绿素b和光合性能综合指数（PIABS）分别降低了35.3%、11.8%、20.6%、25%、21.1%、20%、23.8%；干旱胁迫程度越重对6WC雌雄穗的发育影响越大。此外，LD与MD分别延长6WC的开花吐丝间隔期（ASI）至5天、9天，LD和MD分别延长Z58的ASI 0、3天。综上所述：穗期的干旱胁迫在不同程度上影响了6WC和Z58穗位叶的光合特性，但是对干旱敏感自交系6WC雌雄穗的生长发育的抑制显著高于Z58，以至于降低了干物质向穗部的积累与分配。 Abstract:Maize is one of the grain crops with a large demand of water. Its ear period from jointing stage to anthesis stage is the critical period of its life. It is significant meaningful to study the response mechanism of ear stage to drought stress for improving drought adaptability of maize. In this paper, drought sensitive inbred line PH6WC (6WC) and drought-resistant inbred line Zheng 58 (Z58) were selected as experimental materials. Water control experiment was performed in the pit, and three water treatments (normal irrigation CK, mild drought LD, and moderate drought MD) were set up at ear period, drought treatment would recover to the normal water level after anthesis stage. The ear and tassel development characteristics, anthesis-silking interval (ASI), and the influence of ear leaf photosynthetic characteristics were measured under different water treatments. The results showed that LD didn't significantly affect plant height, growth characteristics of ear, relative content of chlorophyll, and maximum photochemical efficiency of PSII in Z58, but significantly decreased the length of ear. MD significantly reduced photosynthetic characteristics, ear length and dry matter accumulation of both ear and tassel in Z58. As for 6WC, LD inhibited the growth of plant and the development of ear, reduced the length and diameter of ear, length of tassel, distribution ratio of dry matter to ear, the content of chlorophyll a and b, and composite index of photosynthetic performance (PIABS) by 35.3%, 11.8%, 20.6%, 25.0%, 21.1%, 20.0% and 23.8%, respectively. The higher the degree of drought stress was, the greater the influence on the development of 6WC ear was. In addition, LD and MD resulted in 5 and 9 days' delay in ASI of 6WC, respectively; LD and MD resulted in 0 and 3 days' delay in ASI of Z58, respectively. To sum up, the drought stress at ear stage affected the photosynthesis characteristics of 6WC and Z58 to different degrees, furtherly the growth and development of ear and tassel of the drought sensitive inbred line was inhibited significantly more than that of the drought-resistant inbred line, which reduced the accumulation and distribution of dry matter to ear. 参考文献 相似文献 引证文献

Which plant traits are most strongly related to post-silking nitrogen uptake in maize under water and/or nitrogen stress?

The impact of grain yield on post-silking N uptake (PostN) in maize has been a major focus of previous studies, although results are mixed as to the direction and magnitude of the relationship between these two variables. The objective of this study was to understand how grain yield and other plant traits interact with exogenous N and water availability to regulate PostN in maize. In a greenhouse experiment, maize was subjected to high or low levels of N and water supply pre-silking during vegetative growth, which created large variations in source and sink components such as ear size and leaf area. Notably, these large differences in source and sink components were generated not by cutting off plant organs but instead by relying on maize response to vegetative-stage N and water stress. These plants were then subject to high and low levels of N and water supply post-silking, and the relationship between plant traits and PostN was characterized. Final grain yield was irrevocably reduced in the treatments where pre-silking water stress occurred compared to the well-watered pre-silking treatments (30 g plant−1−1 vs. 106 g plant−1). Because of the reduced ear sink strength in the treatments experiencing pre-silking water stress, post-silking biomass (PostBM) and PostN accumulated in vegetative organs. This resulted in greater PostN at maturity in the lower yielding treatments when post-silking water and/or N stress occurred (1.1 vs. 0.6 g N plant−1). Due to the shift in assimilate and N partitioning towards vegetative organs, leaf CER and root dry weight during grain-fill were better maintained in the lower yielding treatments. We conclude that while biomass accumulation (PostBM) regulates PostN, under post-silking N or water stress, shifting sink organs from the grain to vegetative structures increases PostN by improving vegetative organ function and enhancing post-silking source-sink ratios.

SOME MAIZE LEAF GROWTH TRAITS AS INFLUENCED BY SOME INTEGRATED FERTILIZATION REGIMES

A field experiment was conducted at the summer season of 2017, and then repeated at the summer season of 2018 in Agricultural Research Station. Faculty of Agric., Zigzag Univ., Sharkia Governorate, Egypt. The study investigated the impact of eleven nitrogen and five phosphorus fertilization regimes on some leaf traits 70 days after sowing (DAS) of maize cultivar single hybrid 168. Results showed that, 120kg N/fad., from different sources i.e., chemical fertilizer, compost and biofertilizers were effectless on number of leaves/plant at 70 days after sowing (DAS) of both seasons and their combined analysis. Number of leaves either under or above the ear of mono eared maize plant were not affected due to applying different nitrogen fertilization regimes studied. Leaf area/maize plant was significantly affected in the first season only. The largest leaf erea/plant (4254.22 cm2/plant) was obtained in the first season, with the appliance of the integrated N fertilization regime (90 kg N from chemical fertilizer +30 kg N from compost). Area of leaves under ear resulted from the integrated fertilization regime (cerealine + 60 kg chemical N+ 60 kg N from compost) was larger than that in the control treatment by 30.94% based on combined results. Regarding to the area of leaves above the ear, results of the 1st season displayed that area of leaves above the ear were at par in treatments N2, N3, N4, N5 and N6. Application of either 120kg chemical fertilizer (N2) or 90 kg chemical N +30 kg N from compost (N3) was conjucated with larger values of leaf area index comparably with other regimes. According to combined analysis, ear leaf area ranged from 481.87 cm2 in control treatment to 625.89 cm2 in the integrated nitrogen fertilization regimes comprised of cerealine + 60 kg chemical N/fad. + 60 kgN from compost. From the results of combined analysis, it could be noted that tassel leaf area ranged between 150.99 to 217.87 cm2 under biofertilization (N11) and the integrated fertilization regimes (N8)in the same order. Insignificant phosphorus fertilization effect under study on maize leaf traits studied at 70DAS, was recorded in both seasons and the combined analysis.

Agronomic Responses of Maize Hybrids to Row Spacing and Plant Population in the Summer and Winter Seasons in Brazil

Brazil has two growing seasons for maize (Zea mays L.) production: summer and winter. The additional maize produced in the winter and the high‐yielding opportunities in the summer season make it important to understand responses of maize hybrids to row spacing and plant population across the two annual Brazilian growing seasons. In the 2015 to 2016 summer season and the 2016 winter season, maize response to plant population, ranging from 60,000 to 90,000 plants ha−1, was evaluated for three hybrids in 0.45‐, 0.60‐, 0.75‐, and 0.90‐m row spacing. Plant architecture traits, grain yield and yield components did not differ with row spacing, and their responses to plant population were not affected by hybrid type and/or row spacing. The DKB390PRO2 hybrid (single cross) demonstrated better grain yield performance in the summer, whereas the BG7049YH hybrid (three‐way cross) had the highest yield in the winter. Plant and ear height increased linearly in response to plant population in the summer season, whereas other plant architecture traits, ear leaf chlorophyll concentration, and grain yield components decreased linearly with increasing plant populations in both seasons. There was a quadratic response in maize grain yield to plant population, and it was maximized with 78,688 plants ha−1 in the summer, and 71,206 plants ha−1 in the winter. Our results show preliminary evidence that regardless of row spacing, maize grain yield can be maximized with DKB390 hybrid (single cross) with 78,500 plants ha−1 in the summer, and BG7049YH hybrid (three‐way) with 71,000 plants ha−1 in the winter season.Core Ideas Regardless of summer or winter seasons, hybrid performance was not affected by row spacing. Maize hybrids exhibited similar yield responses to row spacing and plant population. Most of the yield components and plant architecture traits decreased linearly with increasing plant population. The maximum grain yield occurring at lower plant population (71,000 plants ha−1) in the winter than in the summer season (78,500 plants ha−1).

Maize Yield and the Associated Weeds as Affected by Plant Population Density and Weed Control Treatments

Two field experiments were carried out in the Farm of Agricultural Research and the Experimental Center of Faculty of Agriculture at Moshtohor, (Toukh Directorate, Qalyubia Governorate) Benha Univ. Egypt, during 2017 and 2018 seasons to investigate the effect of five plant population densities, i.e. 18, 21, 24, 27 and 30 thousand maize plants/feddan (fed) {one fed = 4200 m2} and five weed control treatments, i.e.pendimethalin 682.5 g a.i./fed (stomp extra 45.5 % CS),acetochlor840 g a.i./fed (harness 84 % EC), nicosulfuron24 g a.i./fed (active 6 % SC), hand hoeingtwice and the unweeded check (the control) on yield, some of its components and associated weeds in maize (single cross hybrid 2036 for MisrHytech Seed Int.). Increasing plant population density from 18 to 30 thousand maize plants/fed reduced weed biomass at 50 days after sowing as well as significantly increased mean values of silking date, leaf area index at 80 days after sowing, plant height, ear height, No. of barren plants/fed, No. of ears/fed and stover yield/fed in both seasons. On the other hand, mean values of area of topmost ear leaf at 80 days after sowing, leaf area/plant at 80 days after sowing, stem diameter, No. of plants carried two ears/fed, ear length, No. of kernels/ear, weight of kernels/ear, shelling %, 100-kernel weight and harvest index were significantly decreased in the two seasons.Maize planted at 24000 plants/fed produced the highest mean values of grain and biological yields/fed in both seasons. Weed control by hand hoeing twice or using nicosulfuron herbicide surpassed the other weed control treatments in depressing mean values of fresh and dry weights of broad-leaved, grassy and total annual weeds at 50 days after sowing maize, as well as gave the best mean values of all maize traits without significant difference between them. Maize planted at 30000 plants/fed under mechanical weed control (hand hoeing twice) or using nicosulfuron herbicide gave the lowest mean values of all weed measurements at 50 days after sowing as well as gave the greatest mean values of leaf area index, plant height, ear height, No. of ears/fed and stover yield/fed in both seasons. The greatest mean values of area of topmost ear leaf, leaf area/plant, No. of kernels/ear, weight of kernels/ear and 100-kernel weight were obtained from planting 18000 maize plants/fed with hand hoeing twice. Maize planted at 24000 plants/fed and hand hoeing twice produced the greatest mean values of biological yield/fed in both seasons. The maximummean values of grain yield/fed were obtained by maize planted at 24000 and 21000 plants/fed and hand hoeing twice the first and second seasons, respectively.Planting maize by 21000 plants/fed with hand hoeing twice gave the highest mean values of nitrogen uptake/fed and protein yield/fed in both seasons.

Effects of maize organ-specific drought stress response on yields from transcriptome analysis

BackgroundDrought is a serious causal factor of reduced crop yields than any other abiotic stresses. As one of the most widely distributed crops, maize plants frequently suffer from drought stress, which causes great losses in the final kernel yield. Drought stress response in plants showed tissue- and developmental stage-specific characteristics.ResultsIn this study, the ears at the V9 stage, kernels and ear leaf at the 5DAP (days after pollination) stage of maize were used for morphological, physiological and comparative transcriptomics analysis to understand the different features of “sink” or “source” organs and the effects on kernel yield under drought stress conditions. The ABA-, NAC-mediate signaling pathway, osmotic protective substance synthesis and protein folding response were identified as common drought stress response in the three organs. Tissue-specific drought stress responses and the regulators were identified, they were highly correlated with growth, physiological adaptation and yield loss under drought stress. For ears, drought stress inhibited ear elongation, led to the abnormal differentiation of the paired spikelet, and auxin signaling involved in the regulation of cell division and growth and primordium development changes. In the kernels, reduced kernel size caused by drought stress was observed, and the obvious differences of auxin, BR and cytokine signaling transduction appeared, which indicated the modification in carbohydrate metabolism, cell differentiation and growth retardation. For the ear leaf, dramatically and synergistically reduced the expression of photosynthesis genes were observed when suffered from drought stress, the ABA- and NAC- mediate signaling pathway played important roles in the regulation of photosynthesis.ConclusionsTranscriptomic changes caused by drought were highly correlated with developmental and physiological adaptation, which was closely related to the final yield of maize, and a sketch of tissue- and developmental stage-specific responses to drought stress in maize was drafted.

Planting Density Tolerance of High-Yielding Maize and the Mechanisms Underlying Yield Improvement with Subsoiling and Increased Planting Density

This study examined the planting density tolerance, grain yield improvement potential, and mechanisms of high-yielding spring maize varieties under increasing planting density and subsoiling. We planted two high-yielding spring maize varieties with a high or low tolerance to high planting densities (LM33 and XD20, respectively) at five different densities (D1: 60,000 plants ha−1, D2: 75,000 plants ha−1, D3: 90,000 plants ha−1, D4: 105,000 plants ha−1, and D5: 120,000 plants ha−1) using two tillage methods (35-cm subsoiling and 15-cm traditional rotary tillage). The response characteristics used to compare the performance of the two maize varieties under different planting densities and tillage methods included root characteristics, canopy physiology, yield, and yield components. The results show that: (1) Under rotary tillage, with the increase of planting density from 75,000 plants ha−1 to 90,000 plants ha−1, yields of high-yielding spring maize varieties improved. However, when the planting densities were beyond 90,000 plants ha−1, the yields stopped increase, or even decrease. Subsoiling increased the planting density by 15,000 plants ha−1, enhanced the highest yield by 1080 kg ha−1–1940 kg ha−1, and raised the yield gain by 11.17–30.72%. (2) Under rotary tillage, the functional indexes of the roots and canopy of high-yielding spring maize decreased as planting density increased, and the largest reductions of root dry weight, leaf area index (LAI) of post-anthesis, light transmission percentage (LTP) of ear leaves, bottom leaves LTP, and dry matter accumulation all occurred between D2 and D4. The largest decline of high tolerance variety emerged between D3 and D5, and the extent was smaller than the low tolerance variety. (3) Compared with rotary tillage, subsoiling reduced the extent declines in root dry weight, root length, and root surface area; delayed the attenuation of LAI and the relative chlorophyll content (SPAD) determined in leaves; and improved the LTP of ear layers and bottom layer during the late growth stage. The post-anthesis populations dry matter accumulation of XD20 and LM33 increased by 7.07% and 13.18%, respectively. In addition, subsoiling significantly increased the number of kernels/spike and 1000-grain weight as the planting density increased. Meanwhile, the planting densities at which dry root weight, population LAI, ear leaf LTP, bottom leaf LTP, and dry matter accumulation arose the largest reductions was raised to 15,000 plants ha−1. The effects of subsoiling in the high density-tolerant variety were more pronounced than the low density-tolerant variety.

Genetical studies of corn crop to exploit heterosis, proportional contribution and gene action at diverse water regimes

The study is based on mating fashion of line × tester and its relative analysis to exploit the heterosis, proportional contribution of diverse lines, testers, their interaction and gene action in cross combinations of different corn genotypes under different water regimes. Total 12 parents comprised of eight lines and four testers; crossed to produce 32F1 hybrids. Parents including their hybrids were evaluated in CRD with three water treatments under controlled conditions with three replications in two seasons. Heterosis, percent contribution of lines, testers and line × tester interaction and gene action were studied for the traits i.e. ear leaf area, number of kernel rows per ear, 100 grain weight, biological yield, vegetative dry matter and anthesis-silking interval. Variable heterosis both in magnitude and direction was observed. Both additive and non-additive gene effects have role in the control of anthesis-silking interval; whereas non-additive gene effects were observed for ear leaf area, number of kernel rows per ear, 100 grain weight, biological yield and vegetative dry matter. However100 seed weight was mainly affected by dominance effects under this study that helped for the selection of parents to be used for the development of synthetics and hybrids durable for different water regimes. Keywords: Additive; Hybrid; Line × tester; Susceptible; Water stress http://dx.doi.org/10.19045/bspab.2019.80077

The foliar application of a mixture of semisynthetic chitosan derivatives induces tolerance to water deficit in maize, improving the antioxidant system and increasing photosynthesis and grain yield

Research has shown that chitosan induces plant stress tolerance and protection, but few studies have explored chemical modifications of chitosan and their effects on plants under water stress. Chitosan and its derivatives were applied (isolated or in mixture) to maize hybrids sensitive to water deficit under greenhouse conditions through foliar spraying at the pre-flowering stage. After the application, water deficit was induced for 15 days. Analyses of leaves and biochemical gas exchange in the ear leaf were performed on the first and fifteenth days of the stress period. Production attributes were also analysed at the end of the experiment. In general, the application of the two chitosan derivatives or their mixture potentiated the activities of the antioxidant enzymes superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and guaiacol peroxidase at the beginning of the stress period, in addition to reducing lipid peroxidation (malonaldehyde content) and increasing gas exchange and proline contents at the end of the stress period. The derivatives also increased the content of phenolic compounds and the activity of enzymes involved in their production (phenylalanine ammonia lyase and tyrosine ammonia lyase). Dehydroascorbate reductase and compounds such as total soluble sugars, total amino acids, starch, grain yield and harvest index increased for both the derivatives and chitosan. However, the mixture of derivatives was the treatment that led to the higher increase in grain yield and harvest index compared to the other treatments. The application of semisynthetic molecules derived from chitosan yielded greater leaf gas exchange and a higher incidence of the biochemical conditions that relieve plant stress.

Corn Response to Long‐Term Phosphorus Fertilizer Application Rate and Placement with Strip‐Tillage

Core Ideas Results showed a significant effect of P fertilizer rate and placement in early season whole plant P uptake, ear leaf P concentration, grain P concentration, and yield over the course of this study but particularly after multiple years of treatment application. Early P uptake in corn was consistently higher with deep band P fertilizer applications and with starter fertilizer with the planter. The long‐term evaluation of P fertilizer placement showed that deep‐band P placement only seldom resulted in higher yields. The use of starter fertilizer increased average grain yield, particularly for high‐yielding systems. Multiple years of phosphorus (P) fertilizer application may be needed before the agronomic and environmental effect of P fertilizer placement and application rate become noticeable. The objective of this study was to evaluate the long‐term effects of P placement on corn (Zea mays L.) with strip‐tillage. The study was conducted for 10 yr at two locations in Kansas in a corn and soybean (Glycine max L.) rotation from 2006 to 2015. Strip‐tillage was conducted before corn and soybean were planted without previous tillage. Phosphorus fertilizer placement and rate treatments included a control, broadcast at 20 kg P ha−1 and 39 kg P ha−1, deep‐band at 20 kg P ha−1, and 39 kg P ha−1, in a factorial combination with two starter fertilizer treatments (with and without starter fertilizer). Response parameters included V6 whole plant P uptake, ear leaf P, grain P concentration, and yield. Phosphorus fertilizer increased crop response parameters when compared to the control including yield for some years or across years at the two locations. However, corn response was similar among the P rate‐place treatments with generally higher values for the P rate of 39 kg P ha−1. The use of starter fertilizers in combination with broadcast or deep‐band P fertilizer resulted in greater P uptake, ear leaf P and grain P; however only increased yield at one location. Results from this study showed similar corn yield for deep‐band and broadcast P fertilizer under strip‐tillage and starter fertilizer increased yield for a high‐yielding, low soil test P location.

Reaction of popcorn lines (s7) cultivated in distinct phosphorus levels to Bipolaris maydis infection

ABSTRACT Popcorn culture is highly susceptible to helminthosporiosis (Bipolaris maydis) (h-Bm). The genetic breeding of this culture should prioritize resistance to h-Bm and develop cultivars that offer greater crop sustainability, especially in soils with phosphorus (P) scarcity. P-mineral is usually supplied to maize culture by the application of phosphate fertilizers, which are produced from mineral sources rich in P, the natural reserves of which will be depleted in the medium term. With the aim of selecting popcorn genotypes resistant to h-Bm and with higher P utilization capacity, the present study evaluated h-Bm incidence and severity for 25 popcorn lines (S7) cultivated under high and low phosphorus conditions. There was a significant interaction between genotype (lines) and P fertilization for h-Bm resistance, expressed as disease severity values in the first ear leaf. There was genetic variability for disease resistance. The incidence analysis identifies the lines L-65 L-69, L-70 and L-76 as potentially resistant genotypes, presenting low mean values of h-Bm. The severity analysis, however, presents L-69, L-76, P-3 and P-7 genotypes as potentially resistant in environments with fertilization and without fertilization. The obtained data show that the lines L-69 and L-76 had the best resistance performance in both environments. The genetic resistance to h-Bm can somehow correlate with the response to P fertilization at planting in soils with low natural fertility.