Effect of iron chlorosis-inducing factors on the pH of the cytoplasm of sunflower (Helianthus annuus)

Summary Growth chamber experiments with sunflower in nutrient solution were performed to investigate the effect of phosphorus and bicarbonate in inducing iron chlorosis.Iron chlorosis as proved by lower dry matter yield and reduced chlorophyll content was induced by bicarbonate alone and more pronounced by a combination of bicarbonate and phosphate, but not by phosphate alone.Iron content of roots and aerial plant parts was reduced by bicarbonate in all experiments, but only in one experiment by phosphate alone.Bicarbonate in the nutrient medium increased the pH of the cytoplasm in leaf cells, while phosphate had no effect.A daily adjustment of the pH in the nutrient medium to a value comparable to that in the bicarbonate trial, did not affect the pH of the cytoplasm.It is concluded that the pH of the cytoplasm plays an important role in establishing plant resistance or susceptibility to Fe chlorosis.     

Bicarbonate concentration as affected by soil water content controls iron nutrition of peanut plants in a calcareous soil.

Strategy I peanut plants are frequently subjected to iron deficiency when growing in calcareous soils, which contain high concentrations of bicarbonate. In calcareous soils under field conditions, it has been noted that chlorosis increases in severity after excessive rainfall or irrigation, but the chlorosis symptoms of peanuts are alleviated after waterlogged soils dry. A pot experiment was conducted simulating the chlorosis symptom observed in the field when peanut plants are exposed to fluctuating soil water content induced from rainfall or irrigation. We investigated the bicarbonate fluctuations resulting from adjustable soil water content (SWC) that could lead to bicarbonate-induced iron chlorosis of peanuts growing in calcareous soil. The experiments included three treatments of SWC (50% of water holding capacity (WHC), 80% of WHC, and 100% of WHC) under two levels of CaCO(3) concentrations (at 8.67% and 18.67%.) The results showed that the iron nutrition of peanuts could be regulated by different SWC at both CaCO(3) levels. Our observations indicate that iron deficiency chlorosis symptoms in peanuts grown in high soil water content were more severe, compared to those of peanuts in lower soil water content. A shift from high soil water content to lower soil water content could improve or eliminate the iron deficiency chlorosis symptom of peanuts. The HCO(3)(-) concentration in the peanut rhizosphere increased with increasing SWC and CaCO(3) content and it correlated with the level of soil water content. We suggest that variations in the soil water content could induce HCO(3)(-) concentration variation in the rhizosphere of peanuts. Consequently, the high HCO(3)(-) concentration, which is induced by a high water content in calcareous soil and a high CaCO(3) level, could inhibit the physiological response to iron deficiency of peanuts, resulting in iron deficiency chlorosis. The study indicates that a reasonable agricultural practice of irrigation and drainage should be considered to improve and prevent iron deficiency chlorosis of strategy I plants in calcareous soil.     

The influence of organic fertilizers,obtained from poplar barks,on the correction of iron chlorosis ofLupinus albus L.

Summary The influence exerted by organic matter on the correction of iron chlorosis inLupinus albus L., grown in calcareous soil, was studied through a pot experiment by incorporating two rates (1.5 per cent and 3 per cent on the soil) of three organic fertilizers obtained from poplar barks. The fertilizers differed in the length of humification process and in the integration with different materials,i.e.: H fertilizer: 8 months humified poplar barks without any addition, HF fertilizer: 4 years humified poplar barks with 4 per cent of metallic iron, HP fertilizer: 18 months humified poplar barks with 25 per cent of poultry manure. The higher rate (3 per cent) of the H fertilizer was the most efficient in reducing chlorosis symptoms and gave the greatest dry matter yield. Among the treatments with the lower rate (1.5 per cent), the HF fertilizer gave the best results; conversely, the HP fertilizer failed to correct chlorosis and to enhance yield. Therefore the experiment suggested that organic fertilizers are useful to correct iron chlorosis, provided their phosphorus content is low and they have undergone a prolonged humification process; furthermore, integration with small amounts of iron leads to a considerable saving of organic fertilizer.     

Physiological and biochemical responses of the iron chlorosis tolerant grapevine rootstock 140 Ruggeri to iron deficiency and bicarbonate

Background and aims

Iron (Fe) deficiency chlorosis associated with high levels of soil bicarbonate is one of the main nutritional disorders observed in sensitive grapevine genotypes. The aim of the experiment was to assess both the independent and combined effects of Fe and bicarbonate nutrition in grapevine.

Methods

Plants of the Fe chlorosis tolerant 140 Ruggeri rootstock were grown with and without Fe(III)-EDTA and bicarbonate in the nutrient solution. SPAD index, plant growth, root enzyme (PEPC, MDH, CS, NADP⁺ ?IDH) activities, kinetic properties of root PEPC, organic acid concentrations in roots and xylem sap and xylem sap pH were determined. A factorial statistical design with two factors (Fe and BIC) and two levels of each factor was adopted: +Fe and ?Fe, and +BIC and ?BIC.

Results

This rootstock strongly reacted to Fe deficiency by activating several response mechanisms at different physiological levels. The presence of bicarbonate in the nutrient solution changed the activity of PEPC and TCA related enzymes (CS, NADP⁺-IDH) and the accumulation/translocation of organic acids in roots of Fe-deprived plants. Moreover, this genotype increased root biomass and root malic acid concentration in response to high bicarbonate levels in the substrate. Bicarbonate also enhanced leaf chlorophyll content.

Conclusions

Along with a clear independent effect on Fe nutrition, our data support a modulating role of bicarbonate on Fe deficiency response mechanisms at root level.     

石灰性土壤上HCO3-诱导花生缺铁失绿机制

采用土壤-营养液结合的分根培养方法,研究了部分根系供应HCO- 3或铁对花生铁营养的调控及其作用机制。结果表明,对花生部分根系供应HCO- 3或铁可以调控花生的铁营养,仅供HCO- 3可以诱导缺铁,而只供铁能矫正失绿,同时供应HCO- 3和铁时则不引起失绿。在花生新生叶失绿和复绿的过程中,其中的活性铁含量和全铁含量也有相应的消长。当花生表现缺铁失绿症状时,地上各部分的全铁含量显著降低,而土中根的全铁含量不降低、质外体铁含量升高。在HCO- 3存在的条件下,不同部分根系的铁( )还原酶活性因其生长介质而不同,营养液中根系的铁( )还原酶活性降低而土中根的铁( )还原酶活性不受影响。当花生表现缺铁失绿症状时,土壤中HCO- 3含量升高,有效铁含量不高,p H值无变化。因此,本试验证实了石灰性土壤上的高HCO- 3含量,主要是降低了花生地上部的铁含量而引起失绿,而且花生缺铁失绿又导致土壤HCO- 3含量升高     

Varietal differences in mungbean (Vigna radiata) for growth, yield, toxicity symptoms and cadmium accumulation

Increased cadmium (Cd) contamination of soils resulting from industrial activities is critical to crop production. The objective of this study was to find varietal differences for foliar chlorosis and necrosis, growth and Cd accumulation in mungbean (Vigna radiata). Despite substantial varietal differences, increased Cd levels reduced the shoot and root dry weight and the number and area of leaves at different growth stages. Applied Cd stress produced the foliar symptoms such as marginal and intervein chlorosis and scattered necrotic spots on younger leaves while accelerating the senescence of older leaves. Slope of regression equation and correlations of shoot Cd content with foliar Cd toxicity revealed that leaf chlorosis was more damaging than necrosis. At maturity, number of pods per plant and seeds per pod were maximally reduced to 37% and 26%, while 100‐seed weight, seed yield and harvest index showed 61%, 79% and 54% reduction, respectively, as a result of Cd toxicity. Results suggested that although varietal difference exists, the accumulated Cd is mainly toxic to the mesophyll tissue, most probably by interfering with the uptake of essential nutrients, thereby reducing growth and yield at various stages. Therefore, selection programmes based on foliar toxicity criteria may be beneficial for better utilisation of Cd‐polluted soils.     

Yield-loss Models for Tobacco Infected with Meloidogyne incognita as Affected by Soil Moisture

Yield-loss models were developed for tobacco infected with Meloidogyne incognita grown in microplots under various irrigation regimes. The rate of relative yield loss per initial nematode density (Pi), where relative yield is a proportion of the value of the harvested leaves in uninfected plants with the same irrigation treatment, was greater under conditions of water stress or with high irrigation than at an intermediate level of soil moisture. The maximum rate of plant growth per degree-day (base 10 C) was reduced as nematode Pi increased when plots contained adequate water. When plants were under water stress, increasing Pi did not luther reduce the maximum rate of plant growth (water stress was the limiting factor). Cumulative soil matric potential values were calculated to describe the relationship between available water in the soil (matric potential) due to the irrigation treatments and subsequent plant growth.     

Crop production and management under saline conditions

Summary This review evaluates management practices that may minimize yield reduction under saline conditions according to three strategies: (I) control of root-zone salinity; (II) reduced damage to the crop; (III) reduced damage to individual plants. Plant response to salinity is described by an unchanged yield up to a threshold soil salinity (a), then a linear reduction in relative yield (b), to a maximum soil salinity that corresponds to zero yield (Y_o). Strategies I and II do not take into consideration any change in the parameters of the response curve, while strategy III is aimed at modifying them.Control of root zone salinity is obtained by irrigation and leaching. From the review of existing data it is concluded that the effective soil salinity parameter should be taken as the mean electrical conductivity of the saturated paste extract or of the soil solution over time and space. Several irrigation and leaching practices are discussed. It is shown that intermittent leaching is more advantageous than leaching at each irrigation. Specific cultivation and irrigation practices that result in soil salinity reduction adjacent to young seedlings and the use of water of low salinity at specifically sensitive growth stages may be highly beneficial. Recent data do not show that reduced irrigation intervals improve crop response more under saline than under nonsaline irrigation. Alternate use of water of different salt concentrations results in mixing in the soil and the crop responds to the mean water salinity.Reduced damage at the fiel level when soil or irrigation water salinity is too high to maintain full yield of single plants requires a larger crop stand. For row crops reduced inter-row spacing is more effective than reduced intra-row spacing.Reduced damage at the plant level while the salinity tolerance of the plants remains constant shows up in the response curve parameters as larger threshold and slope and constant salinity at zero yield. This is the effect of a reduced atmospheric water demand that results in reduced stress in the plant under given salinity. Management can also change the salt tolerance of the crop. This will show up as higher salinity at zero yield, as well as changes in threshold and slope. Such changes in the response curve were found at different growth stages, under different atmospheric CO₂, under different fertilization, and when sprinkler irrigation was compared with drip irrigation.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 1111-E 1984 series.     

A physiological study ofTeucrium scorodonia ecotypes which differ in their susceptibility to lime-induced chlorosis and iron-deficiency chlorosis

Summary Edaphic ecotypes ofTeucrium scorodonia have been shown which differ in their susceptibility to lime-induced chlorosis. Plants especially resistant or susceptible to lime-induced chlorosis were found to be similarly resistant or susceptible to iron-deficiency chlorosis. Differences were found in the chlorophyll-iron and dry weight-chlorophyll relationships of the leaves of green and chloroticTeucrium plants, similar effects being produced by growth on a calcareous soil, in iron-deficient culture or by bicarbonate treatment. Chlorotic leaves had less chlorophyll per unit iron but had a greater dry weight per unit chlorophyll than green material. Chlorotic leaves were found to be reduced in both leaf area and dry weight compared with green ones, the reduction in dry weight being the greatest. Common root abnormalities were noted in chlorotic material induced by the above three methods.Evidence was produced which suggested that the difference between chlorosis-resistant and susceptible plants lay in qualitative differences in their iron transport compounds produced within the rootstock. Differential iron uptake was not suggested as a cause of the differences in behaviour. There was, however, evidence of a key role of the root iron pool in population differences in chlorosis susceptibility.Bicarbonate was found to suppress first iron uptake and then iron translocation. A possible causal role of the bicarbonate ion in lime-induced chlorosis was suggested through these effects and through its possible effect on the production of iron-transport compounds.     

Distribution of Nitrogen during Growth of Sunflower (Helianthus annuus L.)

The accumulation, distribution and redistribution of dry matterand nitrogen is described for Helianthus annuus L. cv. Hysun21 grown on 6 mM urea in glasshouse culture. Seed dry matterand nitrogen were transferred to seedlings with net efficienciesof 40 and 86 per cent respectively. At flowering, the stem hadmost of the plant's dry matter and the leaves most of its nitrogen.About 35 per cent of the plant's nitrogen accumulated afterthree-row anthesis. The amount of protein in vegetative parts,especially leaves, declined after flowering. Concentrationsof free amino compounds also decreased during growth. Matureseeds had 38 per cent of the total plant dry weight and 68 percent of the total nitrogen. Seeds acquired 33 per cent of theirdry matter and nitrogen from redistribution from above-groundplant parts. The stem was most important for storage of carbohydrate,leaves the most important for nitrogen. Over 50 per cent ofthe nitrogen in the stem and leaves was redistributed. Plantsthat received 6 mM nitrate accumulated more dry matter thanurea-grown plants. Seeds from nitrate-grown plants were heavier(58 mg) than those of urea-grown plants (46 mg), and their percentageoil was greater (50 and 41 respectively). The amount of nitrogenper seed was the same. Little or no urea was detected in xylem sap of plants suppliedwith 5 mM urea, but it was detected in sap of plants which received25 mM. Concentrations of urea and amino compounds in the sapdecreased up the stem. Plants supplied with nitrate had mostof the nitrogen in xylem sap as NO₂^–, suggesting littlenitrate reduction in roots. Plants grown on 6 mM nitrate andchanged to high levels of urea-nitrogen for 14 days still hadhigh levels of nitrate; little nitrate remained in plants receivinglow levels of urea. When urea is applied in irrigation waterto field-grown sunflower, the nitrogen is subsequently takenup as nitrate due to rapid nitrogen transformations in the soil. Helianthus annuus L., sunflower, urea, nitrate, nitrogen transport, xylem sap, nitrogen accumulation nitrogen distribution     

Iron and ferritin accumulate in separate cellular locations in <Emphasis Type="Italic">Phaseolus</Emphasis> seeds

Background  

Iron is an important micronutrient for all living organisms. Almost 25% of the world population is affected by iron deficiency, a leading cause of anemia. In plants, iron deficiency leads to chlorosis and reduced yield. Both animals and plants may suffer from iron deficiency when their diet or environment lacks bioavailable iron. A sustainable way to reduce iron malnutrition in humans is to develop staple crops with increased content of bioavailable iron. Knowledge of where and how iron accumulates in seeds of crop plants will increase the understanding of plant iron metabolism and will assist in the production of staples with increased bioavailable iron.     

The Influence of Urea and Other Nitrogen Sources on Growth Rate of Scots Pine Seedlings

The growth rate and water content of urea-fed seedlings of Pinus silvestris L. were compared with those of nitrate-and ammonium-fed seedlings grown in continuously renewed nutrient solutions, in which the hydrolysis of urea to ammonia and carbon dioxide was minimized. The growth rate of seedlings grown in an ammonium nutrient solution, in an urea nutrient solution and in a nitrate nutrient solution was about 90 per cent, 75 per cent and 60 per cent, respectively, of that of seedlings grown in a mixture of ammonium and nitrate. Seedlings with urea as the sole nitrogen source developed very severe chlorosis of the needles, the old roots were dark-coloured, the whole root system was very fragile, and the lateral roots of the third order were missing. Urea-grown seedlings had the highest nitrogen contents, closely followed by the ammonium and the ammonium + nitrate seedlings. The lowest nitrogen level was in nitrate seedlings. The low growth rate and the chlorosis of urea-fed seedlings were suggested to be the result of a hydrolysis of urea inside the root, causing an increase in pH and an accumulation of ammonia in the root.     

Effects of irrigation rhythm on growth,fruit-set,yield and quality of egg plant (Solanum melongena) in southern France

Summary Responses of egg plant crop to 3 irrigation rhythms based on the daily potential evapotranspiration were investigated. Results showed that the shorter the rhythm (5 times per week) the better the plant growth expressed in terms of plant length (Fig. 2) and/or yield shown as fruit number (Fig. 3) or fruit fresh weight (Fig. 4). The twice per week rhythm gave the medium, whereas the 10 days one gave the least plant growth and yield. Also the frequent rhythm (5 times per week) gave an earlier crop presented as flower-setting (Table 2).The three rhythms did not show an effect on crop quality expressed as mineral content of leaf blades, petioles or fruits. But results showed that leaf blades usually have higher mineral content than the fruits especially with the micro elements. re]19750305     

石羊河流域干旱荒漠绿洲区不同滴灌模式下葡萄茎液流变化及其与环境因子的关系

研究了石羊河流域干旱荒漠绿洲区交替滴灌（ADI）、固定滴灌（FDI）和常规滴灌（CDI）模式下葡萄茎液流的变化规律及其与气象因子和土壤含水率的相关关系.结果表明：研究区葡萄茎液流表现出与太阳辐射同步的昼夜变化节律;新梢生长期和开花期CDI处理的茎液流量显著大于其它两个处理;影响瞬时茎液流的主要气象因子是太阳辐射和气温,日茎液流量与平均气温和风速具有线性相关关系;不同灌溉方式下葡萄茎液流与气象因素的相关程度依次为：CDI>ADI>FDI;葡萄日茎液流量与参考作物蒸发蒸腾量（ET₀）呈显著线性相关关系.与CDI相比,ADI节省50%水量,而茎液流总量仅降低6.56%,且其葡萄茎液流和水分传导具有明显的补偿效应.     

Iron deficiency in lentil: Yield loss and geographic distribution in a germplasm collection

Iron deficiency symptoms are observed on some genotypes of lentil (Lens culinaris Medikus) grown in calcareous soil. A germplasm collection of 3512 accessions originating from 18 countries was characterized for iron deficiency in a Calcic Rhodoxeralf soil at ICARDA, Tel Hadya, Syria in the 1979/80 season. At 105 days after sowing, 592 accessions, representing 16.9% of the collection, showed chlorosis symptoms characteristic of iron (Fe) deficiency. The Fe deficiency was verified by foliar application of Fe-chelate. Germplasm from different countries showed differences in iron deficiency, with those accessions exhibiting symptoms of iron deficiency mostly originating from relatively warm climates such as India (37.5% accessions showing Fe deficiency) and Ethiopia (30%). Populations from those Mediterranean countries where lentil originated (Syria and Turkey) exhibited Fe-deficiency symptoms only at very low frequencies. Fe-deficiency induced chlorosis was positively correlated with cold susceptibility. Fe chlorosis was transient, the deficiency symptoms largely disappearing during reproductive growth at a time, coinciding with increases in soil temperature and daylength-conditions favorable for plant growth. In Indian germplasm, mild deficiency symptoms did not lead to reduced seed yield, but there was a major yield reduction of 47% in those accessions with the most severe symptoms. Straw yields was reduced commensurately with the severity of symptoms. ei]Section editor: B G Rolfe     

Tolerance of wheat and pea to boron in irrigation water

In a micro-plot experiment 1.5 ppm boron in the irrigation water was toxic for wheat. Its concentration in the soil solution increased to 1.53 ppm and in the plant tissue to 58 ppm. In pea plants 4 ppm B in the irrigation water was toxic with 2.00 ppm soil solution B and 213 ppm tissue B. Nitrogen in both species increased significantly and calcium decreased with the increase in B in irrigation water. The yield of wheat grain declined by 13, 20 and 32 per cent at the 4.0, 6.0 and 8.0 ppm B respectively. The yield of straw and grains of pea declined by 31, 56 and 41, 56 per cent at 6.0 and 8.0 ppm B levels respectively. Thus tolerance to B in irrigation water was between 3.0 and 4.0 ppm for wheat and 4.0 and 6.0 ppm for pea.     

Effect of cellulose wastes upon the growth of Phragmites australis

Growth responses of Phragmites australis (Cav.) Trin. Ex Steud, (reed grass), a helophyte species, were examined under in vitro and greenhouse conditions in the presence of various residues from a Kraft pulp mill. Plant tolerance to solid residues (ashes, dregs, flyashes, grits, primary sludge, and brown stock rejects) was tested in vitro. Solid residues were added separately up to 30% (w/v), as well a liquid residue up to 30% (v/v), to a Murashige and Skoog (1962) sucrose-free nutrient media with (5 mg l(-1)) 6-benzylaminopurine. After 2 mo in vitro, plantlets developed well in the presence of up to 10% solid or liquid wastes, but higher concentrations of either limited growth. This effect was mainly attributed to the plant's uptake and accumulation of various elements such as sodium, iron, copper, manganese, and boron, which are common to these waste types, thus showing an efficient phytoremediation potential. When added to MS media, the concentration of these elements generally decreased in the residual media after 2 mo of culture: the initial sodium, iron, and copper content in the growth media was reduced ca. 10-fold detected; a 5-fold reduction occurred for manganese and boron. In experiments under greenhouse conditions with in vitro propagated plantlets potted in mixtures of a commercial organic soil and residues, significant differences in plant development (plant size and fresh weight increase) were observed in the presence of ashes mixed at levels of 20% and 30%, compared to the control in organic soil. For other solid wastes, plant growth was inhibited as the concentration of each waste increased, causing chlorosis and/or plant necrosis.     

The effect of calcium bicarbonate on iron absorption and distribution byChrysanthemum morifolium, (Ram.)

Summary Plants grown for two weeks in high-bicarbonate nutrient solution with iron became chlorotic, absorbed less iron, and translocated a lower percentage of absorbed iron than did green plants grown under low bicarbonate with iron. Chlorotic plants, pretreated in low-bicarbonate solutions lacking iron, absorbed more iron and translocated a higher percentage to leaves than the green plants. Plants induced to chlorosis by high bicarbonate absorbed less iron after transfer to low-bicarbonate solution containing iron than did chlorotic plants pretreated with low-carbonate solution lacking iron. Initial localization of iron occurred in the roots. A considerable amount of the iron initially found on the roots was translocated to developing shoots over a nine-week period unless the plants were grown in high bicarbonate solutions. More iron was translocated from roots of plants in minus-iron solutions following initial absorption than when iron was supplied in the nutrient solutions. Journal Series Paper736. University of Georgia, College of Agriculture Experiment Stations, College Station, Athens, Ga. 30601.     

Relationships between Nitrate Reductase Activity, Plant Weight and Nitrogen Content in Seedlings of Triticum, Aegilops and Triticale

Seedlings of 12 genotypes were grown in pots and watered withnutrient solutions providing 0, 1, 6 and 20 mg equivalents ofnitrate per I. Increasing the external nitrate supply broughtabout increases in plant weight, nitrate, reduced nitrogen concentrationsand in vivo nitrate reductase activity. When given solutioncontaining 6 mg equivalents of nitrate per litre, the plantscontained approximately 0.1 per cent nitrate, a concentrationsimilarto that found in field-grown plantsat thesamestage of growth.At the 6 mg equivalent level nitrate supply, nitrate reductaseactivity was strongly positively correlated with the concentrationsof nitrate and reduced nitrogen and negatively correlated withplant weight. Similar, though weaker, correlations were foundat the lower and higher levels of nitrate supply. The two Triticalegenotypes however, had higher than average plant weights andnitrate reductase activities, while plants of the two Aegilopsspecies weighed much less, especially at the higher levels ofnitrate supply, than the average of all 12 genotypes and generallyhad correspondingly greater nitrate and reduced nitrogen concentrationsand nitrate reductase activities. For individual genotypes,plant weight at a given level of nitrate supply was stronglycorrelated with weight at all other levels. In a second experiment seedlings of 150 genotypes were grownin compost watered with 10 mM Ca(NO₃)₂ Nitrate and reduced nitrogenconcentrations were negatively correlated with plant weightbut there was no significant correlation between nitrate reductaseactivityand either plant weight, nitrate or reduced nitrogen concentration. The results are taken to indicate that genetic factors, otherthan those determining the supply of reduced nitrogen, werelimiting growth and that as a consequence small plants accumulatednitrate and reduced nitrogen compounds in greater concentrationsthan large ones. The greater nitrate concentrations in smallplants may have induced the increased nitrate reductase activityfound in these, as compared with larger plants. Because plantweight varied more than did reduced nitrogen concentration,variation in reduced nitrogen per plant was more highly correlatedwith plant weight than with per cent reduced nitrogen.     

Effect of irrigation,plant density and fertilisers on yield and NPK uptake by groundnut

Summary Three levels of irrigation, three plant densities and three fertiliser schedules were tested in 3³ factorial confounded design with two replications in winter on sandy loam soils of Tirupati campus of Andhra Pradesh Agricultural University. Pod yield did not vary due to the plant densities and the fertiliser schedules when the crop was sown in optimum time during 1980. When the sowings were delayed, as in 1979, 444000 plants per ha and 60 kg N ha⁻¹, 40 kg P ha⁻¹ and 100 kg K ha⁻¹ was optimum. Scheduling irrigation at 25 or 50% DASM (depletion of available soil moisture) was optimum for the groundnut crop. There was no difference in the uptake of NPK due to irrigations at 25 and 50% DASM in both the years. Low plant density was as effective as high plant density for efficient use of fertilisers. Uptake of NPK by the crop was relatively high at higher fertiliser levels. However, this higher uptake did not contribute to high pod yield, probably due to utilisation of absorbed nutrients for rank vegetative growth.