Agronomic Performance and Nutrient Concentration of Maize (Zea mays L.) as Influenced by Nitrogen Fertilization and Plant Density

A field experiment was conducted at Samaru, Nigeria to study the influence of nitrogen fertilization and plant density on the agronomic performance and nutrient concentration of maize ( Zea mays L.). The treatments were factorial combinations of five nitrogen fertilization rates (0, 50, 100, 150 and 200 kg N/ha) and three plant density levels (25000, 50000 and 75000 plants/ha).
Nitrogen fertilization up to 150 kg N/ha enhanced grain and stover yields and increased kernel number and weight up to 100 kg N/ha. Nitrogen supply also increased maize ear length. Increased N fertilization rates increased concentrations of N, K and Mg but had no effect on P and Ca concentrations. Higher grain yield was closely associated with higher N concentration in ear leaf; with 0.1 % change in N concentration causing 177 kg/ha change in grain yield. Increased plant density increased stover yield up to 50 or 75 thousand plants/ha but depressed kernel number and weight and ear length.     

Growth Patterns of Early Maturing Maize Cultivars

Growth patterns of two early maturing maize cultivars were analyzed, harvesting shoots twice weekly in 1983. Until the end of leaf expansion the leaf dry matter accumulation was highly synchronized in both hybrids. After a short cessation leaf dry weight accumulation was resumed at low to medium rates during the main part of August, during September losses prevailed. During these two months fluctuations in rates were frequent and synchronisation between genotypes small. For stems no transitory cessation of dry matter accumulation occurred; synchronisation between genotypes and fluctuation in rates were less than observed for leaf dry matter accumulation. Losses in stem dry weight mostly coincided with rapid ear growth. Ear dry weight accumulation steeply increased during the first three weeks of August. Fluctuations in rates were large during the following 30 days of rapid growth. This period ended by a sharp decline in rates. Phosphofructokinase activity of upper leaves was maximum in early July followed by a first minimum shortly before anthesis; thereafter the average activity did not change much. The hybrid with higher initial shoot growth rates had a higher phosphofructokinase activity at the same time.     

Smut Disease and Yield Performance in Corn (Zea mays L.) as Influenced by Nitrapyrin, Urea and Zinc Applications in Coarse-textured Soils

The effects of nitrapyrin (NI), urea (U) and Zn rates on rhizosphere pH, smut incidence (S.I.), dry matter (D.M.), grain yield (G.Y.) and ear leaf N and Zn contents were studied in cemented plots, containing calcareous and non-calcareous soils. Treatments were comprised of 3 U applications (46, 92 and 138 kg N acre⁻¹), combined with 2 NI rates (0 and 0.22 kg acre-¹) and 2 levels of Zn (0 and 8 kg acre-¹). Corn seeds, cv 'Amoun' were planted in 1993 and 1994 and the seedlings were artificially infected with U. maydis-spores at the 6 and 10 leaf growth stages. Results have shown that corn plants grown in calcareous soil imposed greater advantage in D.M. and G.Y., accompanied by a relatively low smut infection than those grown in non-calcareous soil. Unlike the diversion effects of NI on soil pH and plant Zn content, its application was beneficial for improving yield and plant Zn content. Urea applications decreased the soil pH by 0.6 unit at the highest N rate and exerted stimulatory effects on ear leaf N and Zn contents. By increasing U rate to 138 kg N acre-¹, smut severity was increased by 6%. In contrast, by Zn fertilization, smut severity was decreased by 10.3%, accompanied by marked increases in G.Y. and leaf Zn content. Mixed results were detected on S.I. data, when NI was combined with U rates. In the presence of Zn, smut severity was dropped to 20.1% at 138 kg N acre-¹. The results also showed that in the absence of Zn supply, S.I. was dominated in NI-treated plants and the reverse was true when Zn was included. Satisfactory results were achieved when 92 kg N acre-¹ were combined with 0.22 and 8 kg acre-¹ of NI and Zn, respectively.     

The Effect of Plastic Mulch and Greenhouse-Raised Seedlings on Yield of Maize

The yield of maize ( Zea mays L.) can be increased appreciably if canopy closure is brought forward. In France and Germany, the use of plastic mulch has boosted dry matter yields of silage maize by approximately 4 t/ha. In Germany, the grain yield of maize plants grown from greenhouse-raised seedlings was 2.4 t/ha more than that of plants grown conventionally. The present study aimed to review and quantify the effect of the use of plastic mulch and greenhouse-raised seedlings on yield of maize. In field trials the effect of a photo-degradable transparent plastic mulch on the yield of two hybrids: Clipper (early-maturing) and Dea (late-maturing) was tested. In two of these trials the effect of using seedlings raised in the greenhouse up to the five-leaf stage was also tested. Crops with plastic mulch required 10 % fewer growing degree days from planting to silking than the unmulched crops, and this number was more constant between years and sites. On average, plastic mulch increased whole plant dry matter content from 29 % to 33 %, and the dry matter of the ear from 45 % to 52 %. In Dea , dry matter yields of the whole plant and of the ear rose by 2.6 and 2.1 t/ha respectively. In Clipper the yield increases were half as large. The regression of whole plant dry matter yield on the sum of global radiation from silking to harvest was similar for mulched and unmulched crops. This suggests that the yield increases obtained with the plastic mulch were largely attributable to advancement of canopy establishment. The whole-plant dry matter yield of plants initially raised in the greenhouse was similar to that of maize sown in situ, but the ear dry matter yield was 2.4 t/ha higher.     

玉米杂交种水分利用效率及相关性状分析

为充分发挥玉米杂交种的水分利用效率,实现玉米高产、高效的目的,本研究以中国生产和推广应用的玉米杂交种为材料,在多变低水条件下,根据成熟期产量水分利用效率剖析其高效性。研究结果表明,不同玉米杂交种间其水分利用效率存在较大的变异范围,玉米杂交种水分利用效率存在着丰富多样的类型;水分利用效率相关性状方差分析结果表明,产量水分利用效率各构成性状在品种间存在着较大差异,不同玉米品种可利用不同性状达到水分的高效利用;简单相关和偏相关分析结果表明,与水分利用效率密切相关的性状是穗行数、行粒数和百粒重。因此,在生产应用中应因地制宜选用不同玉米杂交种,在品种选育过程中应重视相关性状的选择。     

盐胁迫对不同耐盐型玉米品种叶片光合性能和干物质积累与分配的影响

研究盐胁迫对不同耐盐型玉米品种叶片光合性能、干物质积累与分配特征的影响, 为培育耐盐型玉米品种和轻中度盐碱地玉米丰产抗逆栽培提供理论依据。试验于2022—2023年进行, 以耐盐型玉米品种万盛69 (WS69)和盐敏感型玉米品种登海605 (DH605)为材料, 以不施盐处理为对照(CK), 设置低(1.5‰, MS)、高(3.0‰, HS) 2个盐分浓度, 研究土壤盐分对不同耐盐型玉米品种物质生产性能的胁迫效应。盐胁迫显著降低夏玉米叶面积指数、叶绿素相对含量(SPAD值)和叶片光合势; 高盐胁迫处理DH605和WS69夏玉米叶片的平均光合速率(P_n)、气孔导度(G_s)和蒸腾速率(E)较CK分别降低22.11%、19.99%、11.63%和13.51%、13.42%、8.81%, 胞间二氧化碳浓度(C_i)升高19.83%和10.79%。盐胁迫阻碍夏玉米干物质积累速率, 植株生物量、积累速率最大时的生长量(W_max)和最大积累速率(R_max)显著降低, 达到最大积累速率所需天数(T_max)增加。耐盐型品种花后干物质积累所占比例增加, 而盐敏感型品种则降低; 同时盐胁迫降低了干物质向生殖器官的分配比例, 进而造成减产。在MS和HS处理下, DH605平均产量较CK分别降低16.12%和27.42%; WS69平均产量分别降低6.90%和9.12%。盐胁迫后, 耐盐品种保持了较高的叶面积指数、SPAD值和光合势, 叶片光合性能受胁迫程度小, 有利于保持较高光合产物的积累; 盐胁迫显著降低夏玉米花后干物质积累和向生殖器官的分配, 降低收获指数, 从而导致产量降低。     

Effects of Stem-Injected Sucrose on Photosynthesis and Productivity of Water Stressed Corn Plants

Water stress during silking or early kernel development decreases the number of kernels set by corn (Zea mays L.) plants. Previous work has suggested that lack of assimilate supply due to water stress at silking was a major factor in the resulting reproductive failure. A greenhouse experiment was conducted to test the hypothesis that sucrose supplementation of water stressed corn plants can prevent decreased kernel set. Sucrose was injected into corn stems at three concentrations [0 (distilled water), 150 and 300 g L^?1] for 30 days starting at silking. Water availability was controlled by either maintaining a water table at 50 cm from the soil surface (well watered) or by withholding water starting one week before silking (water stress) until the fifth day after silking. The photosynthesis rate of water stressed plants was 25% that of well-water plants on the first day of silking. On average, the daily injection rate for distilled water was 1 mL higher than that of the sucrose treatments over a 30 day injection period. No difference in daily uptake rate was observed between the 150 and 300 g sucrose L^?1 treatments. Over water availability treatments approximately 17 g sucrose were injected into corn plants during the 30 day injection period. Corn plants receiving sufficient water supply produced bigger ears, with more seeds and greater 100-seed weight values, leading to higher total plant dry matter accumulation than water stressed plants. Injection of 300 g sucrose L^?1 increased the weight of the injected internodes by 28%, compared with distilled water injection. The highest grain yield was for the plants injected with 150 g sucrose L^?1, but only under sufficient water supply. The plants injected with 300 g sucrose L^?1 produced the least grain regardless of moisture availability. Thus, the exogenous sucrose supplementation influenced kernel set only under conditions of sufficient soil water supply. These results indicate that plant reproductive development after silking was limited more by water availability than assimilate supply, suggesting that some overall plant response to water stress, perhaps mediated by hormonal signalling, was more important than carbohydrate supply. These results indicated that plant desiccation occurred during floral development or pollination; irreversible loss of florets on unsuccessful pollination could result, thus, grain yield would be limited more by sink size than by availability of photosynthate.     

Allometric Relationships of Growth Components in Maize (Zen mays L.) Cultivars

Allometric relationship (W₁=αW₂^β, where α and β are the parameters) was fitted among growth components in two maize cultivars viz., Decani hybrid and Deccan 101 in order to obtain estimates of other components of the plant system which are time consuming measurements. The results of the agronomic field trial conducted at the University of Agricultural Sciences, Bangalore were used. This model's predictability was compared with linear regression model. In both the cultivars, allometric model using leaf area (LA - W₂.) and leaf dry matter (LDM - W₂) simulated total dry matter production (DMP - W₂) by 79 to 98 % of actual values. Further allometric model fitted well to predict stem dry matter by 91 to 93 % using LDM and LA 89 to 92 % using LDW. Whereas linear regression model estimated total DMP by 95 to 96 % using cob dry matter. In case of LDM - LA association, linear regression model was found to be the best than other model. The leaf area decreased after silking in both the cultivars and the ratio of growth rates of DMP – LA ( β ₂) was negative. Between cultivars, cv. Deccan 101 had higher R² values in most of the relationships than cv. Deccan hybrid indicating the varietal difference.     

‘吉单’玉米品种对种植密度的响应

因吉林省品种层出不穷,却鲜有能够实现大面积推广,本研究以吉林省不同熟期玉米品种‘吉单441’、‘吉单631’和‘吉单558’为试验材料,研究‘吉单’品种在不同种植密度条件下的产量表现,及其在吉林省东部、中部和西部的适宜种植密度。结果表明,‘吉单558’和‘吉单631’在种植密度为7.5×10^4株/hm2时干物质累积量达到最大值,开花期不同种植密度条件下叶面积指数大小顺序均为种植密度(×10^4株/hm^2) 9.0跃7.5跃6.0跃4.5跃3.0。根据实际种植情况、品种特性及方程模拟情况,在吉林省东部适宜种植密度为6.7伊104株/hm^2左右,中部适宜种植密度为6.5伊104株/hm2左右且可根据当地条件适当增加种植密度,在吉林省西部适宜种植密度为6.0伊104株/hm^2左右。随种植密度增加,未见‘吉单’品种倒伏显著相关,6展叶期和乳熟期,干物质累积量与叶面积指数显著相关;开花期(R1)叶绿素相对含量(SPAD值)与叶面积指数均极显著相关,‘吉单558’干物质累积量与产量显著相关,‘吉单631’干物质累积量与叶绿素值显著相关;成熟期仅‘吉单558’表现为干物质累积量与产量显著相关。应根据品种的特性进行合理密植,才能充分发挥品种光合特性,进而提高作物产量。‘吉单’品种为吉林省自主研发玉米品种,本研究可为提高吉林省玉米品种综合竞争力提供理论支持,为吉林省玉米持续丰产提供参考。     

三江地区主栽水稻品种高产群体优化研究

采用裂区设计,于2009 ～2010年对三江地区主栽的4个品种进行高产群体结构优化研究,以明确各品种高产栽培的株行距和穴苗数配置.结果表明,在此地区采用5～8苗/穴、株距10 cm、行距24 cm的配置可以获得高产.建三江科研所的龙粳20号和垦粳3号较生产中常规配置为4苗/穴、株距13.3 cm、行距30 cm的理论产量分别增产43.1％和29.4％,且差异均达到极显著水平;七星研发中心的空育131和龙粳26号的理论产量较常规配置分别增产57.3％和47.9％,差异也达到极显著水平;株、行距与产量均呈负相关,其中株距与产量的负相关多达到显著或极显著水平,株距是3个因子中获得高产的最重要限制因子.因此,对于三江地区从农机上加以改造,这是充分利用当地的自然资源,实现水稻更高产的最为快捷、经济有效的的技术措施.     

Grain Yields and Grain Nitrogen Concentration of Corn as Influenced by Fertilizer Nitrogen Rate

Knowledge of optimum fertilization for com production is required to increase crop yields while minimizing fertilizer costs. Field experiments were carried out from 1988 to 1993 to study the effects of fertilizer N rates on yield and N concentration of corn ( Zea mays L.) grain on a clay soil in Quebec. Grain yields and grain N concentrations generally followed a exponential relationship with increasing N fertilizer rates. The critical grain N concentration, defined as that associated with the highest grain yield, occurred at 285 kg N ha^-1 for all years except 1969 when it occurred at 170 kg N ha^-1. The critical grain N concentrations and grain yields over the years were found to be linearly related. The relationship between the critical grain N concentration and grain yield could serve as a diagnostic tool for N applications.     

Role of Sulphydryl Compounds in Improving Dry Matter Partitioning and Grain Production of Maize (Zea mays L.)

Three sulphydryl compounds, viz., 2-mercaptoethanol, 2-mercaptoethylamine and thiourea, were tested for improving dry matter partitioning and grain production of maize in field culture. The chemicals were applied ca. 0.1 % concentration as foliar spray at grain formation stage. Mercaptoethanol, mercaptoethylamine and thiourea increased grain yield ha⁻¹ by 18.1, 29.2 and 34.1 %, respectively compared with water control Significant improvement in harvest index, a measure of dry matter partitioning for grain production, was also noted with the spray chemicals but stover and biological yields ha⁻¹ remained uninfluenced. Foliar spray of 0.1 % urea did not have any effects on the above parameter and thus the effects of thiourea were largely a function of sulphydryl group. It is suggested that sulphydryl compounds have a considerable potential for increasing grain production of maize and perhaps of similar other cereals.     

不同株行配置与密度对油菜产量的影响

本文系统地研究了4种不同种植密度条件下,3种等行距、3种宽窄行共6种株行配置对油菜经济性状和产量的影响差异,结果表明：不同株行距配置方式对密度在15×104株/hm2油菜产量影响不显著,但对密度45×104株/hm2油菜影响达极显著水平,适宜株行距配置增产效果最高达到19.1%;认为20 cm~40 cm的行距配置有利于当前较高密度直播油菜的生产。     

新疆机采模式下棉花株行距配置对冠层结构指标及产量的影响

【目的】为了研究不同株行距配置对机采棉花冠层结构指标及产量的影响。【方法】在田间条件下,选用棉花杂交种鲁棉研24号和常规品种新陆早60号为供试材料,设置适宜机采的1膜3行等行距(76 cm+76cm+76 cm)低密度、1膜6行宽窄行(66 cm+10 cm)高密度及1膜3行等行距(76 cm+76 cm+76 cm)双株高密度3种配置方式进行试验。【结果】等行距低密度下,棉花生育前期生长旺盛,叶面积指数与光吸收率迅速增加至最高值;生育后期,叶面积指数及光吸收率下降幅度分别为10.4%~13.6%、3.7%~4.2%,低于其他两种处理,且干物质积累量较高。等行距低密度下杂交棉产量最高。【结论】等行距低密度下杂交棉实现高产的生理基础主要是:生育前期叶面积指数及光吸收率增长迅速,干物质积累较快;生育后期叶面积指数及光吸收率下降缓慢,能维持较高水平,光合生产能力较高,干物质积累量最大。