EFFECTS OF SOAKING TEMPERATURE,STRATIFICATION, POTASSIUM NITRATE AND GIBBERELLIC ACID ON SEED GERMINATION OF LOQUAT TREES

The present study was carried out to increase loquat seed germination with treatments consisting of two soaking temperatures (24 ± 2°C and 38 ± 2°C), chemical agents [control, 0.5% potassium nitrate (KNO₃) and 250 mgL^?1 gibberellic acid (GA₃) each for 20 h], and different moist chilling (MC) periods (1, 2, 3 and 4 weeks under 4–5°C). Compared with 24 ± 2°C, soaking at 38 ± 2°C reduced germination%, mean daily germination (MDG), and mean germination time (MGT), plumule and radicle lengths. Germination percentage, days to 50% emergence, fresh weight and lateral root numbers significantly reduced as MC period increased. KNO₃ and GA₃ had no significant effect on germination percentage, MDG, MGT and lateral root numbers. KNO₃ reduced days to 50% emergence and radicle length, but increased fresh weight compared with control and GA₃. Finally, our results suggest the soaking at 24 ± 2°C followed by 0.5% KNO₃ each for 20 h plus 1 week of MC or soaking at 24 ± 2°C followed by 250 mgL^?1 GA₃ each for 20 h plus 2 week of MC.     

Potassium fertilization and soil diagnostic criteria for forage corn (Zea mays L.) production contributing to lower potassium input in regional fertilizer recommendation

Abstract

Effective soil diagnostic criteria for exchangeable potassium (Ex-K) combined with inorganic potassium (K) application rates were developed to lower K input in forage corn (Zea mays L.) production using experimental fields with different application rates and histories of cattle manure compost. Two corn varieties, ‘Cecilia’ as a low K uptake variety and ‘Yumechikara’ as a high K uptake variety, were selected from among 20 varieties and tested to make diagnostic criteria for K fertilization applicable to varieties with different K uptakes. The K uptakes increased from 96 to 303 kg K ha^?1 for ‘Cecilia’ and from 123 to 411 kg K ha^?1 for ‘Yumechikara’ with increasing Ex-K content on a dry soil basis from 0.11 to 0.92 g kg^?1 with no inorganic K fertilizer application. The K uptake by corn for achieving the target dry matter yield of 18 Mg ha^?1 was estimated to be approximately 200 kg K ha^?1 in common between the two varieties. Yields of both varieties achieved the target yield at an Ex-K content of approximately 0.30 g kg^?1 with no K fertilization, although ‘Yumechikara’ reached the target yield at a lower Ex-K content. At the low Ex-K content of 0.1 g kg^?1, inorganic K fertilizer application at 83 kg K ha^?1 was needed to gain the target yield, and apparent K recovery rate for K fertilizer was calculated to be 70% for both varieties. The K uptakes for gaining the target yield by the K fertilization were lower than that by soil K supply. Based on these results, diagnostic criteria of Ex-K and inorganic K application rates were set up as follows: at an Ex-K content of < 0.15 g kg^?1, inorganic K fertilizer is applied at 83 kg K ha^?1 (100 kg ha^?1 as potassium oxide (K₂O) equivalent); at an Ex-K content of 0.15–0.30 g kg^?1, the application rate is reduced to 33 kg K ha^?1 (40 kg K₂O ha^?1); at an Ex-K content of ≥ 0.30 g kg^?1, inorganic K fertilizer is not applied because of sufficient K in the soil. Additionally, we propose that cattle manure compost be used to supplement soil K fertility.     

Relation of Toxicity in Corn Seeds Treated with Zinc and Salicylic Acid

The beneficial effect of corn seed treatment with zinc (Zn) is directly related to the source used. The excess of this micronutrient causes seedling stress and reduces growth. Thus, assuming that the use of exogenous phytohormones can minimize such effects, we evaluated different doses and sources of Zn for the treatment of maize seeds with or without salicylic acid. The experiment took place in the laboratory, and two factorial experiments, 2 × 4 + 1, were performed in a randomized design. The seeds were treated with either ZnO or ZnSO₄ at doses of 0.5, 1, 2, and 3 g.kg^?1 seed with four replications, differing only by the addition of 4.14 mg L^?1 salicylic acid. Treating seeds with Zn and salicylic acid did not affect germination. ZnO led to a greater increase in dry mass in corn seedlings as compared with zinc sulfate, especially at higher doses (2 and 3 g kg^?1 seed). Seed treatment with sulfate reduces root and shoot length, and salicylic acid did not attenuate this toxic effect. Dry mass is not affected when oxide is used. Salicylic acid reduces the accumulation of zinc in the treatment of corn seeds, regardless of the source used.     

Nitrogen application and sowing date affect okra pod and seed characteristics

The effect of nitrogen (N) application rate and sowing date on seed quality and pod production of four cultivars of okra (Abelmoschus esculentus L.) were examined. Seeds of four okra cultivars (cv. ‘Boyatiou’, ‘Veloudo’, ‘Clemson’, and ‘Pylaias’) were sown on 13 May (1st sowing) and 2 June (2nd sowing). Plants were subjected to three N levels: F₁, F₂, and F₃ (150, 300, and 450 mg N L^?1). The 2nd sowing improved flower induction and pod set, without however affecting pod size. The number of seeds per pod was not affected by sowing time, but the mean 100 seed weight was generally lower in the 2nd sowing. In all cultivars, except cv. ‘Veloudo’ germination increased in the 2nd sowing mainly as a result of lower seed hardness. Germination was also improved by increasing N levels, or by seed storage, acid scarification, or seed priming.     

EFFECT OF ARSENIC ON GERMINATION,PHOTOSYNTHESIS AND GROWTH PARAMETERS OF TWO WINTER WHEAT VARIETIES IN IRAN

□ Effects of different arsenic (As) concentration (0–30 mg L^?1) on seed germination, root tolerance index, relative shoot height, root and shoot biomass, photosynthetic pigments and arsenic accumulation in two wheat varieties were investigated. Low concentrations of arsenic (0–2.5 mg L^?1) stimulated germination percentage, shoot and root elongation, plant biomass as well as chlorophyll content as compared with control, however, these factors all decreased gradually at high concentrations of arsenic (5–30 mg L^?1). ‘Zarin’ variety had a significantly higher tolerance to arsenic than ‘Sardari.’ Arsenic accumulation by plants root and shoot increased with the increasing arsenic concentrations in medium, which ‘Zarin’ had a higher ability to absorb and translocate arsenic to the shoots. Root accumulated more arsenic than shoot. The similar trend of chlorophyll content and wheat growth under different arsenic concentration suggesting that arsenic toxicity affects the photosynthesis which ultimately results in the reduction of wheat growth and yield.     

Effects of bentonite on water infiltration in a loamy sand soil

Water loss as deep percolation is considerable in furrow irrigation in light soils due to the high infiltration rate. Application of soil conditioners such as bentonite reduces the infiltration rate and improves irrigation application efficiency (E_a) in these soils. The effects of bentonite application rates (BAR) of 0, 2, 4 and 6 g L^?1 on infiltration of a loamy sand soil were determined in a soil column in the laboratory. The exponent of the Kostiakov infiltration equation was not influenced by BAR. Maximum reduction in infiltration equation coefficient and final infiltration rate (i _f) occurred with 2 g bentonite L^?1 and this reduction was lower on increasing BAR from 2 to 4 and 4 to 6 g L^?1 compared with control. The effect of 2 g L^?1 BAR on infiltration and its effect on the design of furrow irrigation in a field with a loamy sand soil indicated that in the first irrigation after field ploughing and seed planting, longer furrow length, lower deep percolation and higher E_a are obtained.     

Solid-Solution Metal Partitioning for the Upper Mero River Basin (NW Spain)

This study determines the seasonal variability of metal partition coefficients [aluminium (Al), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn)] and analyses the importance of suspended sediments (SS), dissolved organic carbon (DOC) concentrations, pH, and discharge (Q) on the seasonal variability of metal partition coefficients (K_Ds) in the headwaters of the Mero River catchment, which drains an agroforestry area in northwestern Spain. Metal partition coefficients were used as an approach to relate dissolved and particulate fractions. Water samples were collected over 3 years (2005–2008) at the catchment outlet. The mean metal dissolved concentrations were: Fe (43.5 μg L^?1) > Al (23.3 μg L^?1) > Zn (1.8 μg L^?1) > Mn (1.2 μg L^?1) > Cu (0.3 μg L^?1). Partition coefficients followed the order Mn > Al > Fe > Zn > Cu, and their values exhibited low variability. Al, Cu, and Zn partition coefficients presented the greatest values in summer, except during 2007–2008, when the greatest K_Ds value was observed in autumn, whereas the K_Ds of Fe showed the greatest values in winter. The K_D of Mn has no seasonality. For Al, Cu, and Zn, the seasonal SS concentrations were closely related to Kd. For Fe, Kd was more closely related to DOC concentration than to SS concentration.     

Effect of nitrogen application on seed yield,pod and seed characteristics of okra

Four okra cultivars [Abelmoschus esculentus (L.) Moench] were cultivated for two growing periods at nitrogen (N) application rates of 150, 300 and 450 mg N L^?1. There was no effect of N on pod size (length and diameter) or on the number of seeds per pod and seed size (mean 1000 seed weight), all these characteristics of which related to the genotype. High N application (450 mg N L^?1), increased the seed yield of the cultivar with the lowest flower induction (Boyiatiou), but only in experiment 2. In Veloudo, seed yield was highest at 300 mg N L^?1, whereas in Pylaias and Clemson 450 mg N L^?1 reduced seed yield. In all cultivars, seeds produced at an N rate of 450 mg N L^?1 exhibited a significantly higher percent germination N, possibly by reducing the incidence of seed hardness.     

Na compound fertilizer stimulates growth and alleviates water deficit in the succulent xerophyte Nitraria tangutorum (Bobr) after breaking seed dormancy

Nitraria tangutorum (Bobr), a typical succulent xerophyte with high level of seed dormancy, is one of the few shrubs found to date that can develop and form fixed dunes in desert regions. Our studies have demonstrated that the strong drought tolerance of the succulent xerophytes was strongly linked to high sodium (Na⁺) accumulation in the photosynthesizing branches (PB) as well as leaves. The study is to explore a method that can rapidly promote the seed germination of N. tangutorum, and then investigate the positive effects of Na compound fertilizer (NaCF) on the growth and drought tolerance of N. tangutorum and ecological environment by short-term pot experiment in a greenhouse and long-term field and pot experiment in a desert environment. The results indicate that the germination rate of seeds obtained a maximum by 69% when seeds were treated with 150 mg L ^?1 gibberellic acid (GA₃) for 48 h followed by soaking in concentrated sulfuric acid (98% H₂SO₄) for 55 min, and then germinated (25/5°C) in darkness for 8 d. After breaking seed dormancy, the NaCF significantly stimulated growth of N. tangutorum and, concomitantly, improved its ability to cope with water deficit (30% of field water capacity) by increasing Na⁺ more than Potassium (K⁺) accumulation for osmotic adjustment in greenhouse and desert conditions. The contribution (take the pot experiment in the desert, for example) of Na⁺ to the osmotic potential (compared with control) varied from 13.9% in plants subjected to diammonium phosphate [(NH₄)₂HPO₄] to, surprisingly, 63.9% in plants grown in the presence of NaCF under water deficit. The distribution characteristics of the total Na⁺ (1620 mg) in the NaCF indicate that 691.2 mg (42.7%) is absorbed by plants, 848.8 mg (52.4%) remained in the pot and 80 mg (4.9%) leached, which accounted for 2.2% of the nursery soil, respectively. The positive effect of NaCF on the drought resistance of N. tangutorum and the ecological environment were also confirmed in the field experiments. These findings suggest that the rapid seed germination technology of N. tangutorum combined with the popularization and application of NaCF can shorten the seed germination period and make the seedling establishment much easier, which may be an effective strategy to restore and reconstruct degraded vegetation in many desert regions.     

N-Application Methods and Precipitation Pattern Effects on Subsurface Drainage Nitrate Losses and Crop Yields

Diverting the infiltrating water away from the zone of N application can reduce nitrate–nitrogen (NO₃–N) leaching losses to groundwater from agricultural fields. This study was conducted from 2001 through 2005 to determine the effects of N-application methods using a localized compaction and doming (LCD) applicator and spoke injector on NO₃–N leaching losses to subsurface drainage water and corn (Zea mays L.)–soybean (Glycine max L.) yields. The field experiments were conducted at the Iowa State University’s northeastern research center near Nashua, Iowa, on corn–soybean rotation plots under chisel plow system having subsurface drainage ‘tile’ system installed in 1979. The soils at the site are glacial till derived soils. The N-application rates of 168 kg-N ha^?1 were applied to corn only for both the treatments each replicated three times in a randomized complete block design. For combined 5 years, the LCD N-applicator in comparison with spoke injector showed lower flow weighted NO₃–N concentrations in tile water (16.8 vs. 20.1 mg L^?1) from corn plots, greater tile flow (66 vs. 49 mm), almost equivalent NO₃–N leaching loss with tile water (11.5 vs. 11.3 kg-N ha^?1) and similar corn grain yields (11.17 vs. 11.37 Mg ha^?1), respectively, although treatments effects were found to be non-significant (p?=?0.05) statistically. The analysis, however, revealed that amount and temporal distribution of the growing season precipitation also affected the tile flow, NO₃–N leaching loss to subsurface drain water, and corn–soybean yields. Moreover, the spatial variability effects from plot to plot in some cases, resulted in differences of tile flow and NO₃–N leaching losses in the range of three to four times despite being treated with the same management practices. These results indicate that the LCD N-applicator in comparison with spoke injector resulted in lower flow weighted NO₃–N concentrations in subsurface drain water of corn plots; however, strategies need to be developed to reduce the offsite transport of nitrate leaching losses during early spring period from March through June.     

Effects of Some Organic Nitrogen Sources and Antibiotics on Callus Growth of Indica Rice Cultivars

A factorial experiment based on a completely randomized design with three replicates was conducted to evaluate effects of sixteen different mixtures of organic nitrogen sources and antibiotics which were supplemented to an Murashige and Skoog (MS) medium containing 4 mg L^?1 2,4-Dichlorophenoxyacetic acid (2,4-D), 0.4 mg L^?1 benzyl-aminopurine (BAP), 30 g L^?1 sucrose, 8 g L^?1 Agar-agar on fresh weight and dry weight (assessed after three days of drying at 70°C) of calli and in vitro callogenesis from scutellum of four indigenous Iranian Indica rice (Oryza sativa L.) cultivars, including ‘Hashemi’, ‘Gerdeh’, ‘Hasani’, and ‘Gharib’. It was found that proline at 2.8 g L^?1 is the most effective source of organic nitrogen in enhancing growth, whereas asparagine at 0.75 g L^?1 inhibited the calli growth. Hygromycin at 50 mg L^?1, with slight differences between the cultivars, could effectively stunt the growth of untransformed calli. Mixture of cefotaxime (250 mg L^?1) and vancomycin (250 mg L^?1) did not have any significant effects on calli growth, although this treatment was slightly phytotoxic.     

Evaluation of nanosilicon dioxide and chitosan on tissue culture of apple under agar-induced osmotic stress

In vitro, applications of nanosilicon dioxide (SiO₂) and chitosan were investigated for their effects on growth and proliferation of apple (Malus domestica Borkh. ‘Gala’) explants under osmotic stress induced by agar to simulate drought stress and under non-stressed conditions. The experiment included five levels of SiO₂ (0, 25, 50, 100, and 200 mg L^?1), two levels of chitosan (0 and 40 mg L^?1), and two levels of agar (7 g L^?1 and 9 g L^?1) added to Murashige and Skoog medium. Under non-stressed conditions (7 g L^?1 agar), application of SiO₂ at 50 or 100 mg ^?1 increased proliferation of apple explants. Use of 50 or 100 mg L^?1 SiO₂ or 40 mg L^?1 chitosan increased growth of apple explants under osmotic stress (9 g L^?1 agar). This research suggests that use of SiO₂ or chitosan may improve plant growth and tolerance to stress.     

Fulvic acid in foliar spray is more effective than humic acid via soil in improving coffee seedlings growth

ABSTRACT

Humic (HA) and fulvic (FA) acids improve the nutrient availability and uptake by plants but some aspects of their agronomic use still need to be clarified. The effects of HA soil application and FA foliar application on the growth, Zn and B uptake by coffee seedlings were evaluated. HA was added to an Oxisol at concentrations 0, 10, 25, 50, 75 and 100 mg kg^?1 (C-HA), in both limed (pH 6.2) and overlimed (pH 7.2) conditions. FA (0, 0.2, 0.5 and 1 g L^?1 C-FA) was applied to coffee leaves in three different application modes (M): with 0.3% Zn and 0.6% B supplied via foliar (M₁), 0.6% B and 1.2% Zn supplied via foliar (M₂) and 1.2 mg kg^?1 B and 6 mg kg^?1 Zn supplied via soil (M₃). HA addition in soil significantly (p < 0.05) reduced leaf B and Zn accumulation and coffee growth in both pH conditions. In the M₁ and M₂, FA application significantly (p < 0.05) increased the shoot growth at 0.59 and 0.45 g L^?1 and B accumulation at 0.96 and 0.45 g L^?1 C-FA. Foliar application of C-FA, instead soil application of C-HA, is a suitable practice to improve coffee seedlings growth and nutrition on Oxisol.     

Occurrence and Geochemistry of Arsenic in Groundwater of Punjab,Northwest India

Abstract

Arsenic (As) is a deadly poison at high concentrations. It is mysterious in the sense that people are exposed to it most of the time through drinking groundwater, fortunately at much lower concentrations than the deadly levels, and usually without knowing it. Arsenic content in alluvial aquifers of Punjab varied from 3.5 to 688 µg L^?1. Arsenic status of groundwater is classified into low (<10 µg L^?1), moderate (≥10 to <25 µg L^?1), high (≥25 to <50 µg L^?1), and very high (>50 µg L^?1). In zone I, the concentration of As in groundwater varied from 3.5 to 42 µg L^?1 with a mean value of 23.4 µg L^?1. On the basis of these limits, only 8% of samples were low, whereas 51 and 41% of the total samples collected from this region fall in the moderate and high As categories. The concentration of As in groundwater of zone II varied from 9.8 to 42.5 µg L^?1 with a mean value of 24.1 µg L^?1. Arsenic concentration in the alluvial aquifers of the central plain of zone II is 2 and 52% in the low and moderate limits. In this region, 46% of groundwater sites contain high As concentrations. Arsenic concentrations in the aridic southwestern parts are significantly different from other two provinces. The As concentration ranged from 11.4 to 688 µg L^?1 with average value of 76.8 µg L^?1. Eleven percent of the aquifers of the southwestern region of zone III are in the moderate category, 54% in the high, and 35% in the very high. According to safe As limits (<10 µg L^?1), only 3 and 1% of the groundwater samples collected from zones I and II were fit for dinking purposes with respect to As content. In the aridic southwest, zone III, all water samples contained As concentrations greater than the safe limits and thus are not suitable for drinking purposes. The presence of elevated As concentrations in groundwater are generally due to the results of natural occurrences of As in the aquifer materials. The concentration of other competitive oxyanions in waters such as phosphate, sulfate, and borate also depressed the adsorption of As on the sorption sites of aquifer materials and thereby eventually elevate the As concentration in groundwaters. In groundwater of alluvial aquifers of Punjab, released from sulfide oxidation and oxyhydroxide of iron, elevated (>10 µg L^?1) concentrations of As were widespread because of high pH (>8.0) and higher concentrations of phosphate, borate, sulfate, and hydroxyl anions. It is conclusively evident that geochemical conditions, such as pH, oxidation–reduction, associated or competing ions, and evaporative environments have significant effects on As concentration in groundwater. These conditions influence how much As is dissolved or precipitated into the water and how much is bound to the aquifer materials or the solid particles in water.     

Impact of Boron Deficiency on Changes in Biochemical Attributes,Yield, and Seed Reserves in Chickpea

To determine the effect of boron (B) deficiency on biomass, reproductive yield, metabolism, and alterations in seed reserves of chickpea (Cicer arietinum L.) cv. ‘13.G‐256,’ plants were grown in refined sand until maturity at deficient (0.033 mg L^?1) and adequate (0.33 mg L^?1) B, supplied as boric acid (H₃BO₃). Boron‐deficient plants exhibited visible deficiency symptoms in addition to reduced number of pods and seeds, resulting in lowered biomass and economic yield. Boron deficiency lowered the concentration of B in leaves and seeds, photosynthetic pigments (leaves), Hill reaction activity, starch (in leaves and seeds), and proteins and protein N (in seeds), whereas phenols, sugars (in leaves and seeds), and nonprotein N (in seeds) were elevated. Specific activity of peroxidase (POX) increased in leaves and pod wall and decreased in seeds, while activity of acid phosphate and ribonuclease were stimulated in leaves, seeds, and pod wall in B‐deficient chickpea.     

N-Source Effects on Temporal Distribution of NO3-N Leaching Losses to Subsurface Drainage Water

Understanding the temporal distribution of NO₃-N leaching losses from subsurface drained ‘tile’ fields as a function of climate and management practices can help develop strategies for its mitigation. A field study was conducted from 1999 through 2003 to investigate effects of the most vulnerable application of pig manure (fall application and chisel plow), safe application of pig manure (spring application and no-tillage) and common application of artificial nitrogen (UAN spring application and chisel plow) on NO₃-N leaching losses to subsurface drainage water beneath corn (Zea mays L.)–soybean (Glycine max L.) rotation systems as a randomized complete block design. The N application rates averaged over five years ranged from 166 kg-N ha^?1 for spring applied manure to 170 kg-N ha^?1 for UAN and 172 kg-N ha^?1 for fall applied manure. Tillage and nitrogen source effects on tile flow and NO₃-N leaching losses were not significant (P?<?0.05). Fall applied manure with CP resulted in significantly greater corn grain yield (10.8 vs 10.4 Mg ha^?1) compared with the spring manure-NT system. Corn plots with the spring applied manure-NT system gave relatively lower flow weighted NO₃-N concentration of 13.2 mg l^?1 in comparison to corn plots with fall manure-CP (21.6 mg l^?1) and UAN-CP systems (15.9 mg l^?1). Averaged across five years, about 60% of tile flow and NO₃-N leaching losses exited the fields during March through May. Growing season precipitation and cycles of wet and dry years primarily controlled NO₃-N leaching losses from tile drained fields. These results suggest that spring applied manure has potential to reduce NO₃-N concentrations in subsurface drainage water and also strategies need to be developed to reduce early spring NO₃-N leaching losses.     

Establishment of seed germination and micropropagation protocols for Senegalia nigrescens,a potential anti-virulent species

This study describes seed germination and micropropagation of Senegalia nigrescens, an economic, medicinal and nitrogen-fixing species of South Africa. Seeds of S. nigrescens were subjected to pre-sowing treatments including soaking in cold water for 24?h, sulphuric acid (H₂SO₄) or hydrochloric acid (HCl) for 4, 8 and 12?min and mechanically scarifying seeds before sowing on Petri plates with wet filter paper. Mechanically-scarified seeds were also sown aseptically on a filter paper bridge, plain agar, ½ or full strength Murashige and Skoog (MS) basal medium. Single nodal explants from MS-derived seedlings were grown on MS media supplemented with 0.0, 0.5, 1.0 and 2.0 mg?L^?1 of benzylaminopurine (BAP) or kinetin (KIN) and a combination of 0.5 mg?L^?1 of BAP and KIN to investigate shoot multiplication. No significant differences were observed in the number of shoots produced across all treatments. However, the treatment containing 1.0 mg?L^?1 KIN produced a significantly higher shoot length (14.17?±?5.20 mm) than 0.5, 1.0 and 2.0 mg?L^?1 BAP (7.67?±?3.87, 6.75?±?2.93 and 8.70?±?3.56 mm, respectively). The highest rooting rate (16.7%) was obtained on ¼ strength MS supplemented with either indole-3-acetic acid (IAA) or indole-3-butyric acid (IBA) at concentrations 1.0 and 0.5 mg?L^?1, respectively. Rooted plantlets were successfully acclimatised with a 66.7% survival rate. The findings from this study would be of great benefit for the commercial propagation of S. nigrescens.     

Evaluation of growth indices and quantitative traits of safflower under organic farming and conventional agriculture

Application of organic fertilizers in sustainable agriculture systems improves yield sustainability of field crop production. The current research has been formed to investigate the effects of various levels of vermicompost (zero, 3, 6 and 9 t ha^?1) in combination with foliar spraying of potassium humate (0, 1, 2 and 3 mL L^?1) on spring safflower, in Iran during 2012–2013. In addition, inorganic fertilization has been considered as conventional agriculture (CA). In the current experiment, growth indices, seed yield, yield components and flower yield were evaluated. The results showed that the maximum leaf area index, total dry weight and crop growth rate have been determined at 9 t ha^?1 vermicompost and 3 mL L^?1 K-humate while the maximum netto assimilation rate has existed in CA at the emergence of flower buds. Likewise, the results indicated that vermicompost leads to a significant increase in seed yield, flower yield and yield components except 1000 seed weight. Flower yield, head number per plant and seed number per head were affected by K-humate concentrations and increased significantly from 1 to 3 mL L^?1. It should be mentioned that 9 t ha^?1 vermicompost and 3 mL L^?1 K-humate produced the highest seed and flower yield.     

Role of sulfur nutrition in plant and seed metabolism of Glycine max L.

The aim of present investigation has been to explore the effect of sulfur application on plant metabolism, seed yield and seed quality in soybean. The sulfur was supplied in different doses ranging as 1, 2, 4, 6 and 8 meq S L^?1. Plant supplied with 4 meq S L^?1 showed optimal growth. Plant growth and dry matter was reduced under sulfur deficiency (1 and 2 meq S L^?1) and toxicity (6 and 8 meq S L^?1). Application of sulfur increases the tissue sulfur and cysteine concentration in both leaves and seeds. The critical concentration for deficiency (CCD) and toxicity (CCT) of sulfur was observed 0.194 to 0.277% dry weight respectively. Pod yield and seed yield was also suppressed in sulfur deficiency and toxicity. In leaves sugar (reducing, non-reducing and total sugar) and starch was found to be accumulated while in seeds both were depleted under sulfur deficiency and toxicty. Seed storage proteins (albumins, globulins, glutelins and prolamins) were also reduced under sulfur stress. Thus, we conclude that sulfur deficiency and toxicity both affects the plant metabolism, yield and seed quality in terms of carbohydrates and storage proteins of soybean.     

Effects of Seasonal Nitrate Flush on Nitrogen Metabolism and Soluble Fractions Accumulation in Two Rice Varieties

ABSTRACT

Two rice varieties, ‘Piaui’ (a landrace) and ‘IAC-47’ (an improved variety), were grown in nutrient solution containing 20 mg nitrate (NO₃ ^?)-nitrogen (N) L^{? 1} up to 32 days after germination (DAG). After this, a group of plants received 200 mg NO₃ ^?NL^{? 1}, while the other was kept at 20 mg NO₃ ^?NL^{? 1} up to 42 DAG. From 42 until 56 DAG, all plants received 5 mg NO₃ ^?NL^{? 1}. Plants were collected at 42 and 56 DAG, soluble fractions, nitrate reductase (NR) and GS enzymatic activities were determined. The nutritional history of the plants affected significantly the uptake and use of nitrogen (N), and should be taken into consideration in the studies of N-use efficiency. The variety ‘Piaui’ was more efficient than ‘IAC-47’ in N-uptake use, accumulating more NO₃ ^? in its tissues at the initial phases of its cycle for subsequent utilization.