Iron‐stress response of inoculated and non‐inoculated roots of an iron inefficient soybean cultivar in a split‐root system

The objective of this study was to establish whether the iron‐stress responses observed in T203 soybean (Fe‐inefficient) with active nodules are products of the nodules or of the entire root system. A split‐root system was used in which half the roots of each plant were inoculated and actively fixing nitrogen and the other half were not. Soybean cultivar T203 is normally Fe‐inefficient and does not exhibit the Fe‐stress responses, however an iron‐stress response did occur during active N₂ fixation in earlier studies. This implies that the active nodules influenced the plant's ability to respond to Fe‐deficiency stress. In this study, the Fe‐stress response (H⁺ and reductant release) observed in T203 soybean was limited to the inoculated side of the split‐root system. The severe Fe chlorosis which developed in these plants was overcome in a manner similar to Fe‐efficient cultivars undergoing normal Fe‐stress response and the T203 plants completely regreened. Exudation of H⁺ ions was similar in both the presence and absence of Fe, and was generally limited to inoculated roots. Reductant release was nearly nonexistent from the non‐inoculated roots and was greater for the Fe‐stressed (‐Fe) plants than for non‐stressed (+Fe) plants. Thus, the response observed, which alleviated Fe chlorosis, appeared to be associated with N₂ fixation of the active nodules.     

Acid soil tolerances of two wheat cultivars related to soil Ph,KCl‐extractable aluminum and degree of aluminum saturation

Aluminum toxicity, associated with soil acidity, is a major growth‐limiting factor for plants in many parts of the world. More precise criteria are needed for the identification of potential Al toxicity in acid soils. The objective of the current study was to relate the acid soil tolerances of two wheat cultivars to three characteristics of an acid Tatum subsoil (clayey, mixed, thermic, typic Hapludult): pH in a 1:1 soil to water suspension; KCl‐extractable Al; and degree of Al saturation. Aluminum‐tolerant ‘BH 1146’ (Brazil) and Al‐sensitive ‘Sonora 63’ (Mexico) wheat cultivars were grown in greenhouse pots of soil treated with CaCO₃ to establish final soil pH levels of 4.1, 4.6, 4.7, 4.9, 5.2 and 7.3. Soil Al, Ca and Mg were extracted with 1 N KCl, and Al saturation was calculated as KCl‐Al/KCl Al + Ca + Mg%.

Within the soil pH range of 4.1 to 4.9, BH 1146 tops and roots produced significantly more dry matter than did those of Sonora 63; however, at pH 5.2 and 7.3, the top and root yields of the two cultivars were not significantly different. Significant cultivar differences in yield occurred over a range of 36 to 82% saturation of the Tatum soil. Graphs of relative top or root yields against soil pH, KCl‐extractable Al and Al saturation indicated that the two cultivars could be separated for tolerance to Tatum soil under the following conditions: pH less than 5.2 (1:1 soil‐water); KCl‐Al levels greater than 2 c mole kg^‐1 and Al saturations greater than 20%. Results demonstrated that any soil test used to predict Al toxicity in acid soils must take into account the Al tolerances of the plant cultivars involved.     

Effect of aluminum on soybean nodulation and nodule activity in a vertical split‐root system

Soybean plants (Glycine max L. cv Santa Rosa) grown hydroponically in nutrient solutions had reduced nodule mass and numbers in the presence of aluminum (Al). Reduced nodule number was attributed mainly to hydrogen (H) ion toxicity, whereas Al had a stronger effect on nodule growth. Using a vertical split‐root system with Al exclusively in the lower (hydroponic) layer also resulted in a significant reduction of nodulation and nodule growth in the surface compartment (vermiculite). This indirect effect could be attributed mainly to Al rather than H. Subsurface Al had no apparent effect on shoot growth or root growth of the upper compartment, but significantly limited root growth in the lower compartment where it was applied. The indirect effect of Al on nodulation could be a reflection of the abnormal root growth in the lower compartment. Split‐root experiments with a high Al soil, however, produced different effects. High Al in soil used exclusively in the lower compartment did not reduce nodule numbers or mass in the upper compartment despite being more harmful than the Al solutions to nodulation and growth of plants when used in a single compartment. Growth of roots in the subsurface compartment was also much less affected by the high soil Al compared with the Al‐containing nutrient solutions. Nodule activity, as estimated by xylem sap ureide levels, was only reduced after direct exposure of nodules to Al. A pronounced increase in the ratio of asparagine/glutamine occurred in all Al treatments where nodulation was reduced, and in some cases, there was an increase in total amino acid concentration of the xylem sap.     

Effects of long‐term nitrogen dioxide fumigation and nitrate supply on nitrite and Leghemoglobin concentrations,pH, and nitrogenase activity of soybean root nodules

Exposing 12‐day‐old soybean plants to 0.2 ppm nitrogen dioxide (NO₂) for four weeks increased the nitrite concentration and acidity, and decreased the Leghemoglobin (LHb) concentration and the nitrogenase activity of root nodules. The supply of 1 mol.m^‐3 nitrate to the roots intensified the nitrite accumulation, decreased the acidity of the nodules, and alleviated the inhibition of nitrogenase activity by NO₂ fumigation. These results suggested that the inhibition of nitrogen (N₂) fixation by N fertilizer supply might relate to the acid‐alkali balance in nodules.     

Aluminum tolerances of two snapbean cultivars related to organic acid content evaluated by high‐performance liquid chromatography

High‐performance liquid chromatography (HPLC) was used to determine aluminum (Al)‐induced changes in organic acid (OA) concentrations of Al‐tolerant ‘Dade’ and Al‐sensitive ‘Romano’ snapbean cultivars. Two week old ‘Dade’ and ‘Romano’ snapbean were grown in 1/5‐strength Steinberg nutrient solution for 10 days and then subjected to 0, 2, 4, 6, and 8 mg L^‐1 Al treatments at pH 4.5 for an additional 3–15 days. Current studies confirmed earlier findings that the Dade cultivar was significantly more tolerant to Al than the Romano variety. Organic acid analyses were performed on extracts of root and leaf, and on stem exudates. The organic acids were separated on an ion exclusion column using a mobile phase of 0.01 N H₃PO₄. Individual OA were quantified with a variable wavelength detector operating at 210 nm. Aluminum stress tended to reduce the concentrations of citric, malonlc, malic, glycolic, fumaric, and acetic acids in the roots and increased the OA concentrations in stem exudates. In the presence or absence of Al stress, the Al tolerant Dade cultivar contained higher OA concentrations than did the Al‐sensitlve Romano. Aluminum stress reduced total OA levels in root extracts from Al‐sensltive Romano plants to a greater extent than in those of the Al‐tolerant Dade. Malic and citric acid concentrations were decreased more than those of the other organic acids examined. Results indicate that the Al‐tolerant Dade snapbean cultivar has a higher potential for Al‐chelation and detoxification than does the Al‐sensitive Romano. Hence, an Al‐chelation mechansism may be involved in differential Al tolerance within this species.     

Distribution of cations in leaves of salt‐tolerant and salt‐sensitive lines of sunflower under saline conditions

Two lines of sunflower (Helianthrus annuus L.), a salt‐tolerant Euroflor and a salt‐sensitive SMH‐24, were grown for three weeks in sand culture containing 0 or 150 mol/m³ NaCl in full strength Hoagland nutrient solution. Distribution of cations in the leaves of varying ages was determined. The older leaves of SMH‐24 contained more sodium (Na) in the laminae than the younger leaves at the salt treatment, whereas laminae of leaves of varying ages of Euroflor maintained Na concentration almost uniform. Distribution of potassium (K), calcium (Ca), and magnesium (Mg) in the laminae was strongly age‐dependent in both lines, i.e., the older leaves contained greater concentrations of these cations than did the younger leaves. The lines did not differ in concentrations of the three cations. The older leaves of SMH‐24 had significantly lower K/Na ratios than those of Euroflor, but the lines did not differ in lamina Ca/Na ratios. It is concluded that distribution of K, Ca, and Mg in the leaf laminae is age‐dependent. Salt‐tolerance in sunflower is related to exclusion of Na in the leaf laminae and to maintenance of almost uniform concentrations of this ion in leaves of all ages.     

Inadaptive changes in pH with Zn‐stress tolerance in some cultivars of cotton and peanut

The effects of Zn‐stress on pH of the nutrient medium and the occurrence of Zn deficiency symptoms were examined in 12 cotton and 10 peanut cultivars widely grown in several parts of India. It was found that many of the cotton cultivars were able to reduce the pH, but however unable to recover from Zn deficiency. In contrast, all the peanut cultivars tested did not develop Zn‐chlorosis when subjected to Zn‐stress, although the pH reduction was less significant. The study with these crop cultivars revealed that Zn‐stress tolerance response was not related to pH changes in general. The mechanism by which the peanut cultivars made Zn available and thus averted the onset of Zn‐chlorosis was therefore not adaptive to the changes in pH. This feature appeared to be different from the pattern of correlative pH reduction and recovery from Fe‐chlorosis observed in several Fe‐stress tolerant crop cultivars.     

Soil‐boron affects straw quality and other agronomic traits in two cultivars of barley

Abstract

Boron (B) toxicity in crops occurs in many dry areas. However, the effect of high external B levels on straw quality is not known. In this greenhouse study, the responses of straw yield, straw quality, and other characters to high soil B levels were investigated in barley. Two cultivars, Galleon and Harmal, were tested. In Experiment I, three B levels were prepared by mixing 0, 25, and 50 mg B kg^‐1 soil‐mix (designated as B0, B25, and B50, respectively). Straw yield, straw quality (nutritional value), and other characters were measured. In Experiment II, an additional soil B level, prepared by adding 12.5 mg B kg^‐1 soil‐mix (designated as B12), was used. Shoots and roots were harvested at tillering and after heading. In Experiment 1, the B50 treatment improved straw quality, had no effect on straw yield, but decreased grain yield, and harvest index. Considering the shoot B concentrations and B uptake at the tillering stage at moderate to high levels of soil B in both experiments, Galleon was able to restrict B uptake better than Harmal. However, Harmal, unlike Galleon, had a better growth and more tillers at moderate levels of soil‐B than at BO. Since Harmal had higher or similar B concentrations as Galleon, Harmal appeared to tolerate higher tissue B concentrations than Galleon. The limitation of selecting genotypes tolerant to high‐B soil was pointed out, and the need to study adult performance after the initial selection was suggested. The finding on straw quality and yield would be a positive finding for sheep owners in dry areas, where barley straw and stubble are a valuable ruminant feed.     

Ion interactions in calcium‐efficient and calcium‐inefficient tomato lines 1

Two Ca‐efficient and 3 Ca‐inefficient tomato lines selected on the basis of dry matter production, Ca concentrations in tissues, and severity of Ca deficiency symptoms were grown in nutrient solutions containing 6 levels of total Ca ranging from 15 to 365 mg in 70 mg increments. All lines responded to increased Ca supply by increasing in dry weight and by accumulating Ca. The critical Ca concentrations in the shoots were 0.25% and 0.40% on a dry weight basis for the efficient and inefficient lines, respectively. Concentrations of Ca, K, Mg, P, and NO₃ ^‐ were lower in shoots and except for Mg were lower in roots of efficient plants than in the inefficient plants. For all lines as more Ca was available in the media and as Ca increased in the shoots and roots, the concentrations of the nutrients other than Ca declined. The declines in concentrations of K and Mg were not due to dilution by higher dry matter production in the efficient lines relative to the inefficient ones, although the total accumulation of Ca, P, and NO₃ ^‐ did not vary with Ca supplied. Antagonism among cations may account for differences in efficiency among lines of tomato.     

Response of soybean to foliar‐applied boron and magnesium and soil‐applied boron 1

Annual plants may partition carbon (C) preferentially to reproductive structures slowing root elongation and subsequent nutrient uptake. Although foliar applications of nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) supplement uptake by roots, soybean [Glycine max (L.) Merr.] yield increases have not been found in most studies. Experiments were designed to determine if foliar applications of boron (B), magnesium (Mg), or B+Mg would increase soybean yield and if soybean would respond to B applied to the soil several weeks prior to planting. Foliar B or Mg applied separately four times during reproductive growth did not affect soybean yield. However, four foliar applications of B+Mg increased soybean yield 12% at Mt. Vernon and 4% at Columbia over a three‐year period. Two foliar applications of B+Mg during the late reproductive stages increased soybean yield 8% over a two‐year period. The yield increase from foliar B+Mg treatment resulted from an increased number of pods on the main stem (18%) and branches (44%). A 2.8 kg/ha B application to soil eight weeks prior to planting increased soybean yield 11% during the first year and 13% the second year but had no effect on soybean yield by the third year after application. When results from the first two years were combined, 2.8 kg/ha B applied to soil increased the number of pods per branch by 17% and the number of branch pods per plant by 39%. Foliar applications of B+Mg increased soybean yield in four of six site‐years in the three‐year experiments at two locations.     

Agronomic effectiveness of phosphate rock and superphosphate for aluminum‐tolerant and non‐tolerant sorghum cultivars

Abstract

About 35% of soils in Venezuela are acid and low in available phosphorus (P). To solve this problem farmers lime and apply phosphate fertilizers to the soils, but both lime and fertilizers are expensive. A good alternative to overcome soil acidity is the use of aluminum (Al)‐tolerant cultivars. The objective of this study was to test the hypothesis, by use of a pot experiment, that sorghum cultivars tolerant to Al toxicity are able to use P from phosphate rock more efficiently than are susceptible cultivars. Three sorghum (Sorghum bicolor L. Moench) cultivars, Chaguaramas III (Ch), AI‐tolerant, Decalb D59 (D59), and Pioneer 8225 (Pi), both Al‐susceptible, were grown in the greenhouse for 20 and 35 days in two acid soils fertilized with 0 and 100 mg P kg^‐1 as triple superphosphate (SP) and Riecito phosphate rock (PR). Santa Maria soil was very low in available P (2 mg kg^‐1) and highly saturated in Al saturation (64.5%) and Pao soil was higher in available P (20 mg kg^‐1) and low in Al saturation (6.5%). Chaguaramas dry matter production, P uptake and root length was higher in Santa Maria soil as compared with Pi and D59 when grown with both SP and PR fertilization. Chaguaramas response to PR in Pao soil was not as good as in Santa Maria soil. The results of our experiment suggest that Al‐tolerant Ch is able to utilize P from PR more efficiently in soils like Santa Maria than Al‐susceptible cultivare Pi and D59.     

Fe‐deficiency stress tolerance and pH reduction: Some contrasts in the cultivars of sesame and lentil

Fe‐deficiency chlorosis was induced in 4 lentil (Lens esculenta Moench) and 7 sesame (Sesamum indicum L.) cultivars by growing them in full nutrient solution for 20 days and then in the nutrient medium without Fe. In lentil cv. VL‐1, a mild chlorosis appeared but turned green after 14 days of stress. However, this recovery was not paralleled by a decrease in pH of the medium. In sesame, there were differences in the degree of tolerance. The cv. T‐13 did not develop any chlorosis, and the pH was found to steadily decrease to 4.5. The cv. SP‐1181 lowered the pH to only 5.6, and did not recover from the chlorosis. A second pattern was noted in VS‐2, TS‐25, TMV‐3 and TMV‐4; these cultivars reduced the pH to between 4.1 and 4.5; these showed a mild chlorosis which disappeared later.

The results show that the pH reduction is not a requisite for chlorosis recovery, at least in some crop cultivars. There are obviously some other mechanism which makes Fe available to the chlorotic leaves. It is suggested that a retranslocatlon of Fe from the older leaves may take place under the stress condition through some physiological process.     

Application of near‐infrared spectroscopy in analysis of soil mineral nutrients

Abstract

The feasibility of using near‐infrared reflectance spectroscopy (NIRS) was investigated for the analysis of pH, electrical conductivity (EC), phosphorus (P), sulfur (S), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), iron (Fe), and manganese (Mn) in 28 Canadian soil samples from three boreholes down to 10 m in depth. Field moist soil samples were scanned for pH and EC, and air‐dry samples were scanned for the analysis of the elements. Calibrations were developed between the near‐infrared spectral data and results obtained by conventional analyses. The NIR‐predicted values were highly correlated to the measured values obtained by the conventional methods (r²>0.9) for P, Ca, Mg, K, Fe, and Mn, and almost as highly correlated (r²>0.8) for S and Na Results for pH were somewhat less successful (r²>0.6), and appeared to be useful only for screening purposes, whereas EC was not successfully predicted by NIRS in this study. It appeared that NIRS could be a useful method for the rapid, non‐destructive, simultaneous analysis of elemental concentrations in dry soils, useful in routine analysis.     

Aluminium‐induced increase of zeatin riboside and dihydrozeatin riboside in Phaseolus vulgaris L. cultivars

Toxic effects of aluminium (Al) on root tips are considered to decrease export of cytokinins to shoots, and deficiency of cytokinins has been made responsible for Al‐induced inhibition of shoot growth. But no experimental data on the influence of Al on endogenous cytokinin levels in higher plants have been reported. In this study, the endogenous levels of zeatin riboside (ZR) and dihydrozeatin riboside (DHZR) of roots, stems, and leaves of two bean cultivars (Phaseolus vulgaris L. cv Contender and cv Strike) exposed to Al in continuously flowing nutrient solution (pH 4.5) was analysed. The supply of a high Al concentration (sum of monomeric Al species, 127 μM) caused severe inhibition of root elongation in both cultivars. The cv Strike was more affected by both Al‐induced mineral nutrient disorders and Al‐induced alteration of leaf water relationships. In both cultivars Al‐supply significantly increased ZR and DHZR. Leaves of Al‐treated plants exhibited a more than three times higher concentration of ribosylated cytokinins than controls. Nevertheless, stomatal resistance was significantly increased by Al in both cultivars. Our results support the hypothesis that Al affects plants not by inducing deficiency of cytokinins but of some other factor necessary for the manifestation of cytokinin action.     

Comparative response of corn and soybean to seed‐placed phosphorus over a range of soil test phosphorus

Abstract

The responses of corn and soybean to seed‐placed fertilizer were compared over NaHCO₃‐extractable soil phosphorus (P) levels ranging from 3 to 35 ppm in a two‐year experiment. Early season corn and soybean shoot‐P concentrations were increased with increasing soil test P and were increased with seed‐placed P regardless of soil test P, although the increases were greater for corn than soybean. Corn grain yield increased with increasing soil test P to a plateau level and increased with seed‐placed P regardless of soil test P. A side‐band (5 cm × 5 cm) application of 39 kg P ha^‐1 at a low soil test P increased yield more (P<0.15) than application of 7 kg P ha^‐1 with the seed. A side‐band application of 9 kg P ha^‐1 at a medium soil P test did not increase yield. Soybean yield was increased with increasing soil test P one year out of two, but did not respond to seed‐placed P in either year. The yield response of corn was attributed to the increased P concentration prior to the 6‐leaf stage.     

Comparing cultivars of three cool‐season turf‐grasses for potassium uptake kinetics and potassium recovery in the field

Efficient use of potassium (K) by turf depends on the ability of roots to absorb a high proportion of the fertilizer K applied to the soil. Among turfgrass genotypes, variation in K absorption kinetics of roots and its inheritance is important in the development of genotypes that are more efficient in K absorption from the soil. Therefore, K uptake kinetics of six cultivars each of Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and tall fescue (Festuca arundinacea Schreb.) were compared under greenhouse conditions. In 1990 and 1991, field studies of the same cultivars were conducted comparing clipping production rate, leaf blade K concentration, K recovery rate in clippings, K efficiency ratio and visual quality under a moderate K fertilization of 59 kg K/ha/year. Significant differences among species and cultivars were obtained for both absorption kinetics and field recovery of K. Significant correlations between some K uptake parameters and field performance were identified. These results show that genetic differences exist among turfgrasses for K utilization at both the interspecific and intraspecific levels and suggest that a screening program could be developed to identify turfgrass genotypes possessing superior K utilization.     

Variation of early growth and nutrient content of no‐till corn and soybean in relation to soil phosphorus and potassium supplies

Abstract

Knowledge of relationships between variation in early plant growth and soil nutrient supply is needed for effective site‐specific management of no‐till fields. This study assessed relationships between soil test phosphorus (STP) and potassium (STK) with early plant growth and P or K content of young corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] plants in eight no‐till fields. Composite soil (0–15 cm depth) and plant (V5‐V6 growth stages) samples were collected from 400‐m² areas at the center of 0.14‐ha cells of a 16‐cell square grid and from 2‐m² areas spaced 3 m along each of two 150‐m intersecting transects. Correlation, regression, multivariate factor analyses were used to study the relationships between the variables. Variability was higher for samples collected from the transects. Plant dry weight (DW), P uptake (PU), and K uptake (KU) usually were correlated with STP and STK but the correlations varied markedly among fields. Relationships between soil and plant variables could not always be explained by known nutrient sufficiency levels for grain production. Plant P concentration (PC) was not always correlated with STP and sometimes it increased linearly with STP, but other times increased curvilinearly until a maximum was reached. Plant K concentration (KC) usually was correlated with STK, however, and increased linearly with increasing STK even in fields with above‐optimum STK. The results suggest greater susceptibility of early growth to STP than to STK and greater plant capacity to accumulate K compared with P over a wide range of soil nutrient supplies. Variation in STK likely is a major direct cause of variation in KC over a wide range of conditions but variation in STP is not likely a major direct cause of variation in PC when high STP predominates.     

Determination op fluoride in plant samples by a potentiometric method and near‐infrared reflectance spectroscopy

Abstract

The determination of fluoride in plant materials was studied using a specific ion electrode following extraction using either deionized water or 0.1 M perchloric acid.

When the extracting agent was water, the amount of fluoride determined was generally 37% less than that obtained using perchloric acid. However, a close relationship was observed between the amounts extracted by either procedure. When perchloric acid is used, the method was found to be precise (variation coefficient 0.74%), accurate (average recovery 98.67%) and sensitive enough to be used in the routine analysis of plant materials.

The determination of fluoride by near‐infrared reflectance analysis (NIRA) was also used which gave generally acceptable results.     

Effects of Dibutyl phthalate and phthalic acid on chlorosis recovery in iron‐deficiency stressed sorghum cultivars

The effects of DBP (Dibutyl phthalate) and PA (Phthalic acid) supplied to the nutrient medium of Fe‐deficiency stressed sorghum cultivars, CSH‐5, 2077‐A, and CS‐3541 were examined. It was found that both the chemicals (50 mg/1) caused recovery of the cultivars CSH‐5 and 2077‐A in 4 days of treatment. Furthermore, the growth of roots, especially the adventitious roots, was increased by the chemicals.     

Effect of potassium salts on alleviation of lime‐induced chlorosis in soybean 1

Studies were conducted to determine the efficacy of K salts in alleviating lime‐induced chlorosis. Greenhouse studies using a Gibbon silt loam [fine‐silty, mixed (calcareous), mesic Typic Haplaquoll] and a 1: 1 mixture of Gibbon soil and washed sand were conducted with KCl, KNO₃, K₂SO₄, K₂HPO₄, or KHCO₃ applied at rates of 0, 250, and 500 mg K/kg soil. An FeEDDHA treatment was included for comparison. Similar studies were conducted at two field sites known to produce lime‐induced chlorosis. Potassium salts were applied at 0, 20, and 40 g K/m of row. In the greenhouse, plants treated with KCl, KNO₃, and K₂SO₄ on Gibbon soil were less chlorotic than controls or plants treated with K₂HPO₄, or KHCO₃. No K treatment totally alleviated chlorosis except FeEDDHA. Chlorophyll correlated positively with chlorosis rating. No relationship was found between leaf Fe uptake and chlorosis. Plants grown in soil/sand exhibited no chlorosis and had lower Fe uptake than plants grown in Gibbon soil. Thus chlorosis was not due strictly to low soil‐Fe availability or inadequate Fe uptake. Bicarbonate in the soil solutions of both growth media treated with KCl was lower than controls which may explain the reduced chlorosis associated with this treatment.

One field site showed positive effects of K treatments on chlorosis rating, chlorophyll concentration, and seed yield. No treatment was as effective as FeEDDHA in influencing plant growth or yield. Total leaf Fe concentration was unrelated to leaf chlorophyll concentration. Inorganic cation/anion ratios in the plant were from 4.4–8.4 which could cause net H⁺ efflux by the plant and alkalinization of plant tissues. One possibility is that H⁺ efflux solubilizes P in the rhizosphere, which after uptake could immobilize Fe in the plant. Application of KCl, KNO₃, and K₂SO₄ generally lowered HCO₃ content of the upper 15 cm of both soils. High bicarbonate could increase rhizosphere P availability and increase immobilization of Fe in the plant.