Direct and Residual Contributions of Symbiotic Nitrogen Fixation by Legumes to the Yield and Nitrogen Uptake of Maize (Zea mays L.) in the Nigerian Savannah

Field experiments were conducted to determine the direct and residual contributions of legumes to the yield and nitrogen (N) uptake of maize during the wet seasons of 1994 and 1995 at the University Farm, Abubakar Tafawa Balewa University, Bauchi, Nigeria, located in the Northern Guinea savannah of Nigeria. Nodulating soybean, lablab, green gram and black gram contributed to the yield and N uptake of maize either intercropped with the legumes or grown after legumes as a sole crop. Direct transfer of N from the nodulating soybean, lablab, green gram and black gram to the intercropped maize was 24.9–28.1, 23.8–29.2, 19.7–22.1 and 18.4–18.6 kg N ha^–1, respectively. However, the transfer of residual N from these legumes to the succeeding maize crop was 18.4–20.0, 19.5–29.9, 12.0–13.7 and 9.3–10.3 kg N ha^–1, respectively. Four years of continuous lablab cropping resulted in yields and N uptake of the succeeding maize crop grown without fertilizer N that were comparable to the yields and N uptake of the succeeding maize crop supplied with 40–45 kg N ha^–1 and grown after 4 years of continuous sorghum cropping. It may therefore be concluded that nodulating soybean, lablab, green gram and black gram may be either intercropped or grown in rotation with cereals in order to economize the use of fertilizer N for maize production in the Nigerian savannah.     

施氮对大豆根瘤生长和结瘤固氮的影响

采用框栽试验研究了施氮对大豆根瘤生长和结瘤固氮的影响,结果表明,施氮对大豆根瘤形成、生长和固氮能力有显著影响,随着N用量的增加,根瘤干质量、根瘤数量呈现先逐渐增加而后降低的趋势,而固氮酶活性和豆血红蛋白含量则表现为持续下降的趋势,适量施氮对根瘤生长有显著的促进作用,当氮素供应不足时则会抑制根瘤的生长,但当氮素供应过量时也会抑制根瘤的形成.从根瘤干质量和根瘤数量来看,各处理间表现为N100>N200>N50>N25>NO,以N100处理下根瘤干质量最大,根瘤数量最多,显著高于不施氮(N0)和其他施氮处理,从不同生育时期来看,根瘤干质量表现为从苗期到花期再到鼓粒期,大豆根瘤的数量呈现出先明显增加后逐渐减少的趋势,高峰出现在花期,而根瘤数量表现为花期>苗期.施氮显著抑制了固氮酶活性和豆血红蛋白含量,随施氮水平的增加,固氮酶活性和豆血红蛋白含量显著降低,表现为NO>N25>N50>N100>N200,表明施氮使大豆根瘤的固氮效率显著降低,因此,从大豆固氮效率来讲,施氮对大豆根瘤固氮具有抑制作用.方差分析结果表明,施氮和不施氮处理间均达到了5%的差异显著水平.因此,从大豆固氮和氮肥施用平衡的角度来看,应适量施用氮肥,既可以充分利用大豆的固氮功能,节约氮肥,又可以获得较高的产量.     

Nitrogen and Carbofuran Effects on the Growth and Yield Performance of Mungbean (Vigna radiata [L.] Wilczek)

Studies were carried out both in the semi-controlled environment and in the field to evaluate the influence of nitrogen and carbofuran in the growth, dry matter partitioning and yield of mungbean. Both nitrogen and carbofuran increased leaf area, leaf N content, NAR, dry matter, most of the yield attributes, and grain yield. Dry matter accumulation during the reproductive phase was significantly influenced by nitrogen and carbofuran, and method of N application. Plants treated with nitrogen fertilizer and carbofuran produced higher amount of dry matter after flowering; but gave low harvest index values compared to control. The results suggest that mungbean yield can be substantially increased through efficient dry matter partitioning employing agronomic manipulations.     

Responses of Root Nodule Formation and Nitrogen Fixation Activity to Nitrate in a Split-Root System in Peanut (Arachis hypogaea L.)

Peanut is an important constituent of crop rotation systems with various vegetable crops, which need large amounts of inorganic nitrogen. Nitrate inhibits nodule formation and nitrogen fixation of the peanut plants in these cropping systems. To elucidate this nitrate-induced inhibition, an experimental method using a split-root system was designed and the inhibitory level of nitrate (14 m M ) was applied to half of the roots for 5 or 30 days in pot experiments. In the application of nitrate for 5 days, the dry weight, the nitrogen content, and both the number and the fresh weight of nodules for each half of the roots were unaffected by the nitrate applied to the other half. However, the nitrate induced significantly lower nitrogenase activity in the applied half. In the application for 30 days, nitrate induced a significantly higher nitrogen content in the applied half of the roots, and the inhibitory effect on nodulation and nodule development was observed not only in the applied half but also in the other half. Thus, the inhibitory effect of long-term nitrate application on the nodulation and nitrogenase activity of peanut may be systemic, but that of short-term nitrate application, in which external nitrate may regulate nitrogen fixation, may not be systemic.     

Differential Growth, Nodulation and Nitrogen Fixation Efficiency of Groundnut Cultivars Inoculated with Different Rhizobium Strains

Growth, nodulation and nitrogen (N) fixation efficiency of Banki (Local) and ICGS-44 (exotic) varieties of groundnut was significantly ( P < 0.05) improved by their inoculation either with NC-92 or Rudy Patric (R.P.) strains of rhizobium. Nodules did not form without inoculation in plants growing in sterilized sand. Inoculation with R.P. strain of rhizobium resulted in greater shoot growth, N content in shoot and number and weight of nodules in groundnut varieties. The R.P. inoculant increased agronomic efficiency by 112.5 % in Banki and 100 % in ICGS-44 variety of groundnut. Improvement in N fixation efficiency by inoculation with R.P. inoculant was 334 and 286% in Banki and ICGS-44 variety, respectively. However, Physiological efficiency was maximum in Banki variety when inoculated with NC-92 strain of rhizobium.     

Effect of Bradyrhizobium Strain on Combining Ability for Nitrogen Fixation in Peanut (Arachis hypogaea L.)*

Improving the host genotype is one method of increasing biological nitrogen fixation by Bradyrhizobium in symbiosis with peanut (Arachis hypogaea L.), but host-strain interactions also must be considered. The objective of this study was to estimate the effect of Bradyrhizobium strains on the inheritance of traits related to nitrogen fixation. Eight parents and the F₁ generation of a diallel cross were evaluated in symbiosis with two bacterial strains for combining ability in a factorial arrangement in the greenhouse. The parents represented three taxa of cultivated peanuts. The two Bradyrhizobium strains NC 92 and NC 123 produced different general and specific combining ability, maternal (reciprocal general) effects, and reciprocal specific effects for the host genotypes. With strain NC 92, the peanut cultivars NC 7 and NC Ac 2821 had the best general combining ability for all traits evaluated; while, with strain NC 123, Robut 33-1 exhibited a high general combining ability (GCA) for nitrogenase activity and specific activity. Genotype NC Ac 2821, when inoculated with strain NC 123, had a negative GCA effect for nodule number, while with strain NC 92 this cultivar had the highest GCA effect. The importance of strain selection in evaluating lines in a breeding program is discussed.     

Inheritance of Cercospora Leaf Spot Resistance in Mung Bean, Vigna radiata (L.) Wilczek

Inheritance of Cercospora leaf spot resistance in mungbean was studied in 20 crosses involving crosses of resistant × susceptible, resistant × resistant, susceptible × susceptible lines. 3:1 ratio was observed in all 14 F₂s involving resistant × susceptible parents. The inheritance of Cercospora leaf spot resistance is thus controlled by a single recessive gene. Our results are contradictory to observations of Thaklk et al. (1977 a, b) who found monogenic dominant inheritance of Cercospora leaf spot resistance in mungbean.     

Growth, Oxidative Damage and Antioxidant Responses in Greengram (Vigna radiata L.) under Short-term Salinity Stress and its Recovery

Spatio-temporal differences under short-term NaCl-salinity (0, 50, 100, 150 m m l⁻¹) stress for 24 h and post-NaCl recovery after 24 h on the growth, water relations, ionic composition, proline and antioxidants of 12-day-old roots, stem and leaves of Vigna radiata were observed. Fresh and dry weight, relative water content and K⁺ ion decreased, whereas, Na⁺ ion and Na⁺/K⁺ ratio increased significantly in roots, stem and leaves. Post-NaCl recovered roots, stem and leaves showed similar results with lower values. Chlorophyll and carotenoid pigments decreased significantly in the leaves. Peroxide and lipid peroxidation level increased significantly with higher ratio in stressed compared to recovered leaves. Ascorbate and proline content increased significantly with no significant change in glutathione content in stressed roots, stem and leaves. Significant decrease in protein content, SOD, CAT, POX, APX and GR activities was observed in roots with no significant change in stem and leaves. The recovered parts showed similar results except increased POX and GR activities showing a tissue-specific response to NaCl-salinity stress. Improved tolerance to salt stress may be accomplished by increased capacity of antioxidative defence system and by lower level of lipid peroxidation and improvement in the plant water status, activities of some of the antioxidants in the recovered parts suggest that significant tissue differences in response to salt stress in V. radiata is closely related to differences in the activities of antioxidants, ion and proline content.     

Effects of Temperature and Photoperiod on Vegetative and Reproductive Growth of Groundnut (Arachis hypogaea L.)*

Effects of temperature × photoperiod interaction on vegetative and reproductive growth were examined in three selected groundnut genotypes by growing them in controlled-environment growth chambers with three temperature regimes (22/18, 26/22, and 30/26°C, day/night) under long (12 h, long day), and short (9 h, short day) photoperiods. The effect of photoperiod on the total dry-matter production (TDM) was significant with the genotypes producing 32–72% greater dry matter under LD than SD. Temperature × genotype interaction effects were significant, with the dry-matter production being greatest at 26/22°C and least at 30/26°C and 22/18°C in two of the three genotypes. Leaf area (LA) was greater under LD than SD at all temperature regimes. LA accounted for 76% of the variation in shoot + root dry weight (R²= 0.76, P < 0.01). A lack of relationship between LA and pod weight or pod numbers suggested that the pod development is controlled by factors other than carbon assimilation. The temperature × photoperiod interaction was significant for root growth, with the root weight being maximal and photoperiod effects being minimal at 22/18°C, while at 26/22°C, root weight declined and photoperiod effects became prominent. Low temperature (22/18°C) affected the reproductive development by reducing the proportion of reproductive nodes in total (vegetative + reproductive) nodes. The conversion of pegs into pods, as indicated by pod to peg ratio (PPR), was lower in LD than in SD conditions. Results suggested that the PPR could be used as an indicator of genotypic sensitivity to photoperiod in groundnut.     

Effect of CCC on the Growth and Yield of Mung Bean (Vigna radiata [L.] Wilczek var. Guj-2)

Pot experiments were conducted on mung bean by spraying 500, 1000 and 1500 ppm CCC, 14 days after the emergence of seedlings. Results showed that:
CCC application at 1000 and 1500 ppm led to stem shortening.
Dry weight of shoot system, leaf area, leaf thickness and total chlorophyll content were significantly increased by 1000 ppm CCC.
CCC at 1000 ppm increased amylase and invertase activity in the leaf tissue.
CCC at 1000 ppm increased the pod number/plant, seed number/pod, leading to increased seed yield/plant.
CCC had no effect on the 1000 seed weight.     

Interactive Effects of Salinity and Biological Nitrogen Fixation on Chickpea (Cicer arietinum L.) Growth

The effect of salinity on the nodulation, N-fixation and plant growth of selected chickpea- Rhizobium symbionts was studied- Eighteen chickpea rhizobial strains were evaluated for their growth in a broth culture at salinity levels of 0 to 20 dS m⁻¹ of NaCl + Na₂SO₄. Variability in response was high. Salinity generally reduced the lag phase and/or slowed the log phase of multiplication of Rhizobium. Nine chickpea genotypes were also evaluated for salt tolerance during germination and early seedling growth in Petri dishes at five salinity levels (0–32 dS m⁻¹). Chickpea genotypes ILC-205 and ILC-1919 were the most salt-tolerant genotypes. The selected rhizobial strains and chickpea cultivars were combined in a pot experiment aimed at investigating the interactive effect of salinity (3, 6 and 9 dS m⁻¹) and N source (symbiosis vs. inorganic N) on plant growth. Symbiotic plants were more sensitive to salinity than plants fed mineral N. Significant reductions in nodule dry weight (59.8 %) and N fixation (63.5 %) were evident even at the lowest salinity level of 3 dS m-¹. Although nodules were observed in inoculated plants grown at 6 dS m-¹, N-fixation was completely inhibited. The findings indicate that symbiosis is more salt-sensitive than both Rhizobium and the host plant, probably due to a breakdown in one of the processes involved in symbiotic-N fixation. Improvement of salinity tolerance in field grown chickpea may be achieved by application of sufficient amounts of mineral nitrogen.     

Grain Yield of Intercropped Sorghum and Pearl Millet as Influenced by Sorghum Genotype and Cropping Pattern

Intercropping of sorghum and pearl millet with different growth cycles is used widely in third-world countries to ensure and increase yields. However, it is questionable whether yield increases because of intercropping can be maintained under more developed systems, since temporal differences are necessary to allow mechanized planting and harvesting.
Three sorghum hybrids with expected growth cycles from 90 to 110 days were planted in sole stands and in alternate rows and mixed within the rows with a pearl millet hybrid having a growth cycle similar to that of the early sorghum. Sole stands of millet also were included. The plots were planted at three locations in Kansas, two dryland and one including dryland and irrigated. Results show that yields were consistently highest in sole stands of sorghum, owing to the higher yield level of sorghum. No yield increase could be found on a land equivalent ratio basis, indicating no intercropping advantages. However, under good moisture conditions, a tendency toward yield increase was observed with the later maturing sorghums, which had 1–2 weeks of grain filling after the millet was mature. When moisture supply was insufficient, millet showed higher competitiveness for water than sorghum, and sorghum was adversely affected more than pearl millet was favored. It was concluded that moisture conditions have to be good and that temporal differences between sorghum and millet have to be greater than those used in this experiment to achieve intercropping yield advantages.     

Effects of Thiourea, Thiamine and Ascorbic Acid on Growth and Yield of Maize (Zea mays L.)

Three chemicals, viz., thiourea, thiamine and ascorbic acid capable of potentiating-SH turnover, were tested with the objective to improve growth and productivity of maize. Thiourea was tested as seed-soaking and foliar-applied treatments as also in combination. Thiamine and ascorbic acid were tested as foliar sprays alone. Foliar treatments were applied at vegetative stage (30 and 45 days after sowing).
The results of the field experiment showed that seed soaking with thiourea (500 ppm) tended to improve grain yield (13.4 per cent over control), but improvement in biological yield was significant. However, seed soaking plus foliar treatment of thiourea significantly increased both biological and grain yields, besides causing significant improvement in leaf area index and number of green leaves plant^-1. The increase in grain yield ha^-1 was of the order of 34.6 per cent over control.
It was further noted that foliar sprays of thiourea (1000 ppm), thiamine (100 ppm) and ascorbic acid (100 ppm) significantly increased leaf area index, number of green leaves plant^-1 and biological yield ha^-1. These treatments also significantly increased grain yield ha^-1 by 40.6, 20.2 and 26.3 per cent, respectively over control. Improvement in maize yield with thiourea, thiamine and ascorbic acid treatments appeared to have resulted from increased photosynthetic efficiency and canopy photosynthesis on account of the biological activity of -SH group. It was also apparent that leaf senescence was delayed under the influence of these chemicals. It is therefore suggested that thiourea, thiamine and ascorbic acid are the potential bioregulators for improving photosynthetic efficiency and grain yield of maize and possibly other cereals, and that thiourea, a sulphydryl compound, holds considerable promise in this context.     

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.     

玉米籽粒发育性状的遗传及与产量性状关系的研究

在含有 BA(6-苄基腺嘌呤)2.5毫克/升、NAA(萘乙酸)0.1毫克/升的 MS 培养基上诱导苎麻(Boehmeria niveaL.)试管苗未离体叶面生芽。比较了不同激素的效果,在诱导芽形成中 BA 优于 ZT(玉米素)和 KT(激动素)。在叶脉处,特别是在中脉维管束的薄壁细胞容易分裂和脱分化,且具有较强的分化能力。芽在叶面上发生有一定的规律,并对叶面     

Resin-Extractable Phosphorus, Vanadium, Calcium and Magnesium as Factors in Maize (Zea mays L.) Yield

Resin extraction of soil permits evaluation of ratios of readily extracted elements and correlation of concentrations obtained with crop yield. This information provides guidance on potential genotype selection and fertility management. Two hybrids of maize ( Zea mays L.), designated 2292 and 3895, were grown annually in rotational succession on a 3.2-ha site with soybean ( Glycine max L.) and wheat ( Triticum aestivum L.). Soil samples (0–15 cm) were extracted with ion-exchange resins and extracts were analysed with inductively coupled plasma. Data were regressed against crop yield using stepwise multiple correlation methods. Each hybrid was sensitive to unique combinations of extracted chemistries. Both hybrids of maize were sensitive to the resin-extractable V : (V + P) molar ratio and potential losses of ≥ 20 % were indicated as the ratio approached 0.2. A positive response to the Mg : (Mg + Ca) resin-extractable ratio was noted for maize hybrid 2292 in each of three successive years. Changes of yield potentials associated with the Mg : (Mg + Ca) ratio for hybrid 2292 ranged from none to ≥ 20 % as the ratio ranged from 0.2 to about 0.8. The results indicate that, in the presence of large extractable concentrations of competing or inhibitory ions, different approaches to nutrient management in the form of fertilizer nutrient analysis, application, and genotype selection are needed to overcome effects of competing ions.     

Legume Production and Irrigation Strategies in the Aral Sea Basin: Yield,Yield Components,Water Relations and Crop Development of Common Bean (Phaseolus vulgaris L.) and Mungbean (Vigna radiata (L.) Wilczek)

With world population expected to reach 9.2 billion people by 2050, improved irrigation methods will be needed to increase the productivity of agricultural land and improve food supply worldwide. The objective of this work was to examine the effect of regulated deficit irrigation (RDI) and alternate furrow irrigation (AFI) on the yield and yield components of two legume species (common bean and mungbean) produced as a second crop following winter wheat in Uzbekistan, Central Asia. Water relations and crop development were also examined. The research was conducted during two successive growing seasons in the Fergana valley. Production of mungbean using the severe stress RDI treatment in combination with AFI resulted in the highest yields with the lowest quantity of applied water in 2004. In addition, yields of common bean in the moderate stress treatment were not different from the recommended schedule, although irrigation events were decreased from 4 to 2. AFI did not reduce yields, and it did not interact with RDI to reduce yields further. In general, mungbean yields were higher than those of common bean. The combination of AFI and RDI can allow legume production with reduced water inputs.     

Differences between Maize Cultivars in Yield Formation, Nitrogen Uptake and associated Depletion of Soil Nitrate

In a 3-year field experiment conducted on a Gleyic Luvisol in Stuttgart-Hohenheim, ten maize cultivars (nine commercial and one experimental hybrid) were compared in their ability to utilize a high soil nitrogen (N) supply. Total N content of the shoots at about silage maturity ranged from 213 to 328 kg N ha⁻¹ (1986), from 177 to 223 kg N ha⁻¹ (1987) and from 185 to 226 kg N ha⁻¹ (1988). In all three experimental years, total shoot N uptake was significantly positively correlated to stover yield, and also to N concentrations in the ears and in the total plant dry matter. In contrast, a negative correlation between ear yields of the cultivars and total N uptake was indicated. Differences between the cultivars in N uptake were reflected in a corresponding soil nitrate depletion. At harvest, residual nitrate-N in the 0–90 cm soil layer ranged from 34–63 kg N ha⁻¹ m 1987 and 32–71 kg N ha⁻¹ in 1988. The results indicate, that growing of cultivars selected for high N uptake-capactiy of the shoots may contribute to an increased utilization of a high soil N supply and thus to a reduction of nitrate leaching.     

Effect of Deep Placement of Slow-release Fertilizer (Lime Nitrogen) Applied at Different Rates on Growth, N2 Fixation and Yield of Soya Bean (Glycine max [L.] Merr.)

A new fertilization method with deep placement of slow‐release N fertilizers, such as coated urea and lime nitrogen (LN) (calcium cyanamide) at 20 cm depth was found to promote soy bean seed yield. In the present study, the effect of deep placement of LN was investigated on different parameters such as growth, N accumulation, N₂ fixation activity and yield of soy bean by applying LN at different rates in the rotated paddy field of Niigata, Japan. In addition to the basal fertilizer, ammonium sulphate (16 kg N ha^?1), deep placement of LN was conducted by applying various amounts such as 50 kg N ha^?1 (A50), 100 kg N ha^?1 (A100) and 200 kg N ha^?1 (A200) at 20 cm depth in separate plots. A ¹⁵N‐labelled LN fertilizer was also employed for each of the above treatments to calculate N utilization from LN in separate plots. Soya bean plant growth and N₂ fixation activity were periodically analysed. Both plant growth and N accumulation were found to increase with LN treatment compared with control plants. An increase in N₂ fixation activity was found in the A100 plots. The total seed yield was the highest in the deep placement of LN with A100 (73 g per plant) compared with other treatments. The visual quality of harvested seeds also showed that A100 enhanced the quality of seeds compared with other treatments. Thus, it is suggested that N fertilization management with particular reference to optimum amount of fertilizers is important for maximum growth, N₂ fixation and enhancement of seed yield of soy bean.