Shoot Dry Matter Yield Research Articles

Effect of Glomus etunicatum inoculation on aluminum, phosphorus, calcium, and magnesium uptake of two barley genotypes with different aluminum tolerance

This study was conducted to evaluate the effect of vesicular‐arbuscular mycorrhizal (VAM) fungus Glomus etunicatum on growth, absorption, and distribution of calcium (Ca), magnesium (Mg), phosphorus (P), and aluminum (Al) in one Al‐tolerant and one Al‐sensitive barley cultivar. The plants were grown in sand daily irrigated with nutrient solution containing 0 or 600 μM Al at pH 4.8. Significant interaction (P=0.05) among variety, mycorrhiza, and aluminum (VxMxAl) were noted for both shoot and root dry matter (DM); shoot concentration and content of Al, P, Ca, and Mg; root concentration of Al, P, and Mg; and root content of Al, P, Ca, and Mg. With VAM inoculation: i) root colonization degree was about 50% in all treatment, ii) shoot DM yield increased between 30 and 70%, iii) Al concentration and content decrease down to a half both in shoots and roots of sensitive barley, iv) Ca concentration in shoots of sensitive barley showed a high increase at 600 μM Al, and v) P concentration and content in shoots of both varieties increased significantly.

In vitro selection for improved seedling vigour in birdsfoot trefoil (Lotus corniculatus L.)

Establishment of productive stands of birdsfoot trefoil (Lotus corniculatus L.) is often difficult due to poor seedling vigour. Objectives of this study were to evaluate the relative effectiveness of in vitro selection conditions for seedling vigour and to choose the best lines for further evaluation. Birdsfoot trefoil seedlings from cvs. Leo and Upstart were selected on the basis of in vitro rate of germination at 5, 12 and 20 °C and subsequent seedling growth at 20 °C. Two cycles of recurrent selection were carried out. Progeny from both cycles of selection were evaluated under controlled and field conditions. In general, selection temperatures did not significantly affect emergence, individual shoot dry matter production or total shoot dry matter production. Emergence and total shoot dry matter yield were higher for selections within cv. Upstart than for selections within cv. Leo. Seedling vigour of cycle-2 selections was not superior to cycle-1 selections. Failure to make gains during the second cycle of selection is believed to be due to seed sterilization procedures during cycle-2 selection. Germplasms chosen for further evaluation include the 12 °C and 20 °C cycle-1 selections and the 20 °C cycle-2 selection from cv. Upstart. Key words: Lotus corniculatus L., birdsfoot trefoil, seedling vigour, in vitro selection, temperature

Effects of paclobutrazol and nitrogen fertilizer on the growth and yield of maize

In two field experiments conducted in 1991 and 1992 at Akure, Nigeria, 0–12 and 0–24 ml/l of the plant growth regulator, paclobutrazol, and 0, 75 and 150 kg N/ha were applied to maize in factorial combinations. Substantial vegetative growth occurred with increasing N rates in 1991 and this accelerated 50% silking date. Paclobutrazol influenced maize growth at this stage only in 1992 when 12 and 24 ml/l depressed plant height and increased both stem girth and leaf number/plant.Higher paclobutrazol application rates decreased plant height at maturity in both years while, in 1991, 150 kg N/ha enhanced it, and also stem girth and shoot dry matter yield. In 1991, both ear and grain dry weight yield/m2 increased with higher N rates while in 1992 4–24 ml/l paclobutrazol enhanced ear dry yield/m2 compared with untreated maize.Both chlorophyll a and b in the ear leaf increased with higher rates of paclobutrazol and N fertilizer, except in 1992 when high leaf N tended to mask the effect of paclobutrazol. N fertilizer in 1991 enhanced the contents of N and Ca in the ear leaf while depressing P, compared with untreated maize.

PROPORTION OF TOTAL NITROGEN AND FIXED NITROGEN IN SHOOTS OF LENTIL AND CHICKPEA GROWN IN A MEDITERRANEAN-TYPE ENVIRONMENT

Shoot dry matter yield, shoot nitrogen yield and amount of nitrogen derived from fixation are collated for chickpea (Cicer arietinum L.) cv. ILC482 and lentil (Lens culinaris Medic.) cv. ILL8 grown at the ICARDA research station Tel Hadya, Syria over a period of 17 years. Regression analyses of shoot nitrogen yield on shoot dry matter and of the amount of nitrogen fixed on shoot nitrogen yield were undertaken for both species. The intercepts for both analyses with lentil were not significantly different from zero, so the slopes of the lines represented the concentration of nitrogen in the plant tissue (20.6 g kg−1 dry matter) and the proportion of nitrogen derived from fixation 0.75. Data for other cultivars of lentil grown at Tel Hadya and at four other locations in Syria fell within the 95% confidence limits of the original analyses. The intercept of the regression of shoot nitrogen yield on shoot dry matter yield for chickpea grown at Tel Hadya was not significantly different from zero, so the concentration of nitrogen in the plant tissue was constant (17.8 g kg−1 dry matter). The proportion of nitrogen derived from fixation increased asymptotically as the shoot nitrogen yield increased. Data for other cultivars of chickpea grown in different locations were generally similar to those for cv. ILC482 grown at Tel Hadya. It is proposed that generalized relationships between shoot nitrogen yield and shoot dry matter yield, and between amount of nitrogen fixed and shoot nitrogen yield can be established for lentil and chickpea grown in the West Asia–North Africa region. Consequently the amounts of nitrogen fixed by the two crops could be predicted from a knowledge of dry matter production alone.

Nitrate leaching from ploughed pasture and the effectiveness of winter catch crops in reducing leaching losses

Abstract The effect of five catch crops (ryecorn, ryegrass, mustard, lupin, bean) on nitrogen (N) leaching following the autumn ploughing of a grass ley was compared with N leaching from bare fallow soil. The concentrations of nitrate N and ammonium N in the drainage water and the quantities of drainage water from the various treatments were measured over a winter period using undisturbed soil monolith lysimeters. Nitrate was the dominant form of N leached. The amount of N leached from soils with the ryegrass catch crop (2.5 kg N/ha) was considerably less than that leached from fallow soil (33 kg N/ha). Nitrate concentrations in the drainage water from soils growing ryecorn and ryegrass were less than 10 mg N/litre, whereas that from lysimeters growing lupins or beans and from the fallow soil exceeded this value. Shoot dry matter yield for mustard (5.91 t/ha) and ryecorn (5.25 t/ ha) was at least twice that of the other crops and very much higher than the 0.49 t/ha produced by the weeds in the fallow trea...

Effect of glutamate transport and catabolism on symbiotic effectiveness in Rhizobium leguminosarum bv. phaseoli

Seven Tn5 induced mutants unable to use glutamate as sole carbon and nitrogen source were isolated from the effective Rhizobium leguminosarum bv. phaseoli strain P121-R. As indicated by restriction and hybridisation analysis, all the mutants arose from a single Tn5 insertion in the chromosome. The 14C-glutamate uptake rate of the mutants was 76 to 88% lower than that of strain P121-R. Inoculation of Phaseolus vulgaris cv. Labrador with these mutants significantly decreased shoot dry matter yield and the total nitrogen content respectively, as compared to inoculation with the parental strain P121-R. All the mutants formed nodules, however they were smaller, white to greenish and approximately 30% less numerous than those formed by strain P121-R. These observations suggest that glutamate transport and catabolism in R. leguminosarum bv. phaseoli P121-R may play an important role in the establishment of an effective symbiosis in field bean. None of the mutants isolated was an auxotroph. All mutants were unable to grow on aspartate suggesting that glutamate and aspartate, probably have the same transporter as indicated in Rhizobium meliloti and in Bacillus subtilis. All mutants readily used glutamine, proline, arginine as sole carbon and nitrogen source, but grew more slowly than the wild type strain. On the other hand, all the mutants were impaired in growth on histidine and γ-aminobutyrate as sole carbon and nitrogen source. As the catabolism of these amino acids occurs predominantly through glutamate, our results indicate that mutants are also impaired in their ability to use histidine and γ-aminobutyrate as a nitrogen source. Our results also suggest that other amino acids catabolized through the glutamate pathways may be an additional important carbon source for bacteroids in nodules.

Plant and animal constraints to voluntary feed intake associated with fibre characteristics and particle breakdown and passage in ruminants

Effects of artificial shading to 50% sunlight of nitrogen (N) limited tropical pastures of different grass species on a high (clay loam) and low (granitic loam) fertility soil type were evaluated in a semi-arid. subtropical environment over 3 years. The hypothesis was tested that shade can stimulate shoot growth by providing a modified environment more conducive to organic matter breakdown leading to increased mineralisation and availability of soil N, and the ability of tropical grasses to take advantage of this effect was examined. Unfertilised pastures of green panic (Panicum maximum var. trichoglume), buffel (Cenchrus ciliaris). rhodes (Chloris gayana), and speargrass (Heteropogon contortus) in full sun or shaded by sarlon cloth were sampled on 9 occasions. Additional green panic plots on both soils were irrigated for the first 2 years, and all other plots were dependent on natural rainfall. Shoot and root dry matter and N yield, and soil nitrate and ammonia N, were measured. In one set of green panic plots on each soil, canopy. litter, and surface soil temperatures were monitored continuously, and soil moisture at different depths was measured fortnightly. Shade stimulated shoot dry matter yield over the 3 years by up to 37% in green panic. 22% in rhodes, and 9% in speargrass. Shade decreased buffel yield on the clay soil but had no effect on the granitic soil. Relative increases in yield of shoot N were similar to those for shoot dry matter, except for buffel on the granitic soil where N yield was increased by 39% with no increase in shoot growth. Positive shade responses occurred in all 3 years but were reduced by extreme drought in year 3, particularly on the clay soil. Irrigation gave a greater shade response on the clay but not on the granitic soil. Root mass was lower under shade than in full sun. but there was no long-term trend of progressive decrease. and the change in N yield of roots did not appear to explain the gain in shoot N of the shaded pastures. Nitrogen percentage in the youngest expanded leaf was higher in the shade than the sun leaves only after about 2 to 2 5 months of shading. Surface soil nitrate and ammonia concentrations tended to be higher under shade for most harvests. Shade lowered temperature extremes of surface soil and litter by up to 10-12�C, and improved soil water status. compared with the sun plots. Soil water data were analysed to separate effects on plant water stress and soil microbial activity. The consistent positive response of shoot N yield to shade across grass species. weeds, and soil type. the delay in it becoming evident, and its longevity all support the hypothesis that shade enhances organic matter breakdown and N cycling. Harsh surface temperatures and low soil moisture in open sun pastures appear inimical to high microbial activity. Implications for pasture management are discussed. with the caveat that the outlined benefits of artificial shade may not necessarily arise with tree canopies.

Dependency ofCassia siameaon vesicular arbuscular mycorrhizal fungi

Abstract Thirty‐day‐old seedlings of Cassia siamea were transplanted into pots containing a subsurface Oxisol uninoculated or inoculated with Glomus agaregatum at two target soil solution phosphorus (P) concentrations. While no evidence of Vesicular‐arbuscular mycorrhizal fungal (VAMF) colonization was noted in the uninoculated soil, C. siamea roots were colonized to the extent of 63 and 61% at soil P concentrations of 0.02 and 0.2 mg/L, respectively. VAMF colonization led to significant increases in tissue P concentrations measured at harvest at both soil P concentrations. However, shoot dry matter yield was significantly increased only at the first soil P concentration. Shoot dry matter yield of mycorrhizal C. siamea at soil P concentration of 0.02 mg/L was comparable to mycorrhizal growth of C. siamea at soil P concentration of 0.2 mg/L but inferior to the nonmycorrhizal growth of the legume. Based on these response patterns, C. siamea was classified as a highly mycorrhizal dependent species.

Growth and Essential Oil Content ofAngelica archangelicaas Influenced by Light Intensity and Growing Media

ABSTRACT The effects of light levels and growing media on growth and essential oil content in Angelica archangelica were investigated under greenhouse conditions. Eight months after seed sowing, the highest shoot and root dry matter yield (810 g/plant and 438 g/plant respectively) was recorded from sand-hydroponic (SH) grown variants under supplemental light (SL). The highest oil yield (4.03 mg/plant) was produced by SH-grown plants under SL, while the lowest oil yield (1.74 mg/plant) was obtained from plants grown under organic culture with natural light (NL). The contribution of SL to dry matter (DM) shoot production under SH culture was 57%, while for root production this was found to be 61%. The DM root and total shoot yields of organically grown plants under SL declined by 11% and 18%, respectively, due to increased light intensity. Significant differences were found in the distribution of oil content in different organs, root sizes and the grinding of angelica samples. Thick and thin roots were foun...

Greenhouse evaluation of agronomic potential of different sources of phosphate fertilizer in a typical concretionary soil of Northern Ghana

The concretionary soils of Northern Ghana, which are near neutral with respect to pH and which comprise mostly lateritic ferruginous nodules are known to sorb significant amounts of phosphate. Instead of imported superphosphate, the use of less expensive indigenous Togo rock phosphate (PR) or partially acidulated (50%) Togo rock phosphate (PAPR-50), are possible alternative phosphate fertilizer options for these soils. The objective of this research was to evaluate the effectiveness of freshly-applied SSP, PR and PAPR-50, and the effectiveness of the residues of these fertilizers in a glasshouse pot study. Laboratory studies were also undertaken to study the transformation of these fertilizers after their application to the concretionary ferruginous soils. In the greenhouse study, yield of dried tops and the P uptake by the tops of maize var. Dobidi (Zea mays) was used to measure fertilizer effectiveness. One level of P was applied for each fertilizer (26.4 kg P ha−1). Plants were grown for 28 days. After harvesting the first crop, subsequent cropping was carried out to evaluate the effects of the residual P in the pots. The results showed that increases in dry matter yield of shoot and total P uptake followed the trend SSP > PAPR-50 > PR > control. The relative agronomic effciency (RAE) of PAPR-50 was 58% that of commercial SSP in increasing growth of the crop, while that of PR was only 23%. The residual effect of either PAPR-50 or PR on dry matter yield and total P uptake was found to be negligible compared with SSP, suggesting that apatitic P was poorly effective relative to SSP in the used soils. The P fractionation results confirmed that PR and PAPR-50 did not significantly increase any of the P fractions in either the soil fines or nodules after the first crop. By contrast, application of SSP increased all extractable Pi fractions, most of the P added being recovered from the nodules in forms associated with Fe (hydroxide and residual Pi). It is concluded that, relative to SSP, the P from residues of PAPR-50 and PR are poorly effective in the soils studied for sustainable plant production.

The impact of carbofuran soil application on growth and mycorrhizal colonization by Glomus clarum of groundnut

The influence of soil application of carbofuran on the growth response of groundnut, and both mycorrhizal colonization and sporulation of Glomus clarum was studied in a pot culture experiment. Carbofuran application with or without mycorrhizal inoculation increased the height of the potted plants measured 8 weeks after sowing. Mycorrhizal plants were significantly taller than nonmycorrhizal plants at the final harvest time (14 weeks). Carbofuran, at the recommmended field dose of up to 2 kg/ha, greatly increased shoot dry matter and pod yield in mycorrhizal groundnut. Colonization and sporulation by this VAM fungus were also enhanced significantly at these dose levels. The application of carbofuran at 5 kg/ha inhibited both growth and mycorrhizal status of groundnut.

Silicon availability and response of rice and wheat to silicon in calcareous soils

Abstract The 23 surface paddy soils (0–20cm) representing varying range of calcium carbonate (CaCO3) were collected to evaluate silicon (Si) supplying power and the factors which affect Si availability. A pot experiment and consecutive four‐year field trials were also carried out in this study to investigate the response of rice (Oryza sativa L. cv Wuyujing No. 3) and wheat (Triticum aestium L. cv Yangmai No. 5) to Si‐containing materials applied to the calcareous paddy soils. The result indicated that the available Si contents (sodium acetate‐extractable SiO2) of the soils surveyed were much higher than the accepted critical value. Stepwise regression analysis showed that pH value, clay, and CaCO3 contents significantly affected the available Si content. The pot experiment indicated that the grain yield, spike number, and filled grain percentage and ratio of grain/shoot of the Si‐treated rice markedly increased as compared to the control, but Si added had little effect on the shoot dry matter yield and 1...

Interaction of silicon and boron in oilseed rape plants

Abstract Shoot and root dry matter yields of oilseed rape (Brassica napus L.) grown on the solutions containing 0.025 and 5.0 μg boron (B)/mL (referred to as B1 and B3, respectively) were less than those grown on the solutions containing 0.5 μg B/mL (referred to as B2). Silicon (Si) added increased shoot and root dry matter yields of B1‐treated plants, while decreased those of B3‐treated plants. Shoot and root dry matter yields of B2‐treated plants were slightly affected by Si added. The effect of B and Si on leaf area was similar to that on shoot and root dry matter yields. Excessive B supply (B3) and B deficiency (B1) resulted in a decrease in net photosynthetic rate. Silicon added increased the net photosynthetic rate under B deficiency, but had little effect at normal and excessive B levels. Silicon seems to enhance B uptake and accumulation by plants under B deficiency, but depresses B uptake at normal and excessive B levels. The Si/B ratios of B1‐ and B2‐treated plants were much lower than those of ...

Effect of cocoa pod ash on the growth of maize

SUMMARYPot and field experiments were conducted at the Faculty of Agriculture Arable Crops Farm, Kumasi, Ghana during the major rainy season to compare the agronomic efficiency of potassium in cocoa pod ash with that of muriate of potash and to determine the optimum rate of application of cocoa pod ash to maize (Zea mays L. cv. La Posta). Results from the two experiments indicated that the application of 90 kg N/ha and 67 kg P2 O5/ha did not increase shoot dry matter (DM) yield over the control. However, significant increases in DM yield over the control were obtained when N and P were applied together with 56 kg K2O/ha, demonstrating the complementarity of the major nutrient elements N, P and K. Shoot and root DM increased with increasing application of cocoa pod ash. Application of 140 kg/ha cocoa pod as (equivalent to 56 kg K2O/ha) produced the same DM and shoot potassium yields as 56 kg K2O/ha as muriate of potash. The optimum rate of application of cocoa pod ash was 280 kg/ha (112 kg K2O/ha).

Effects of mes [2(n‐morpholino)‐ethanesulfonic acid] and ph on mineral nutrient uptake by mycor‐rhizal and nonmycorrhizal maize

Abstract Mycorrhizal (+VAM) and nonmycorrhizal (‐VAM) maize (Zea mays L.) plants were grown in sand culture in a greenhouse to determine effects of MES [2(N‐morpholino)‐ethanesulfonic acid] (2.0 mM) and pH (4.0, 5.0, 6.0, and 7.0) on mineral nutrient uptake. Plants were inoculated with the vesicular‐arbuscular mycorrhizal (VAM) isolate Glomus intraradices UT143. Shoot and root dry matter yields were lower in plants grown with MES (+MES) than without MES (‐MES), and decreased as pH increased. Shoot concentrations of N, Ca, Mg, Mn, and Zn were generally higher in +MES than in ‐MES plants, and nutrient contents of most nutrients were generally higher in + MES than in ‐MES plants. Concentrations of N, Ca, Mg, and Mn increased and P, S, and Fe decreased, while contents of all measured nutrients except Mn and Zn decreased as pH increased. Concentrations of Mn, Fe, Zn, and Cu were higher in +VAM than in ‐VAM plants, and contents of P and Ca were higher in ‐VAM than in +VAM plants and Zn content was higher in +VA...

Effect of nitrogen fertilizer form on pH of the bulk soil and rhizosphere, and on the growth, phosphorus, and micronutrient uptake of bean

Abstract In a pot experiment, the effects of NO3‐N and NH4‐N fertilizer were examined on the pH of the bulk soil and rhizosphere, and on the growth and nutrient uptake of 18–35‐d old bean plants (Phaseolus vulgaris L.) supplied with KH2PO4 or rock phosphate (Hyperphos). Prior to sowing, the soil was incubated for 16 d to ensure complete nitrification of NH4‐N which decreased bulk soil pH from 6.8 to 5.5. In other pots, a nitrification inhibitor, N‐Serve, was added together with the ammonium fertilizer and after 18 d growth, the pH of the bulk soil was 6.6 while the pH of the rhizosphere decreased to 4.5. Shoot and root dry matter yield was significally greater for plants supplied with KH2PO4 and fertilized with NH4‐N compared with NO3‐N. This increased growth by NH4‐N fed plants was presumably due to a increased nutrient availability caused by the acidification of the bulk soil. Shoot concentrations of ? and micronutrients, such as Fe, Mn, Zn, and Cu, were higher for plants supplied with NH4‐N, and more s...

The effect of preplant nitrogen and soil temperature on yield and nitrogen accumulation of alfalfa1

Abstract Recommendations for the use of preplant N in alfalfa establishment are controversial. Growth chamber experiments were conducted to examine the effect of preplant N and soil temperature on yield and N accumulation of alfalfa (Medicago sativa L.). Alfalfa was grown in river sand at three day/night soil temperatures (18/12°C, 24/16°C, and 27/21°C), and at five levels of preplant N (0, 10, 20, 40, 80 kg ha−1). At 18/12°C, 40 kg ha−1 preplant N resulted in a 69% increase in shoot dry matter yield. Dry matter and N accumulation rates were greatest at 40 and 80 kg ha−1. Preplant N effects on dry matter and N accumulation at 18/12°C were expressed primarily between the early bud and early flowering stages. Assessment of soil temperature and soil N availability is necessary to determine the potential for a yield response of alfalfa to preplant N.

Screening forage and browse legumes germplasm to nutrient stress: II. Tolerance ofLablab purpureusL. to acidity and low phosphorus in two acid soils

Abstract Although lablab (Lablab purpureus L.) is grown in many parts of Africa relatively little investigation has been done on its adaptation to acid soils, which are generally low in available P. In the present study, lablab was evaluated for tolerance to acidity and low available P on two Ethiopian soils. The two soils were a Nitosol (Soddo soil) and a clay loam with 77% Al saturation (Chencha soil). The pH of the Soddo soil unlimed was 4.8 and 5.6 when limed and with 0 and 37.5 mg P/kg soil applied at each lime rate. The treatments on the Chencha soil were pH 4.1 and 5.9 with combinations 0 and 25 mg P/kg added. There were highly significant (P<0.01) differences between the mean shoot and root dry matter yields and the shoot/root ratios of the lablab accessions on the two soils as well as plant height on the Chencha soil. The mean shoot and root dry matter yields were increased by liming alone by 14 and 23%, while P application increased growth by 8 and 12%, respectively. Lime and P together suppress...

The Effect of Temperature on Growth, Development and Nitrogen in Shoots and Roots in Timothy (Phleum pratenseL.), Tested in Growth Chambers

Abstract The effect of temperature on growth, development and crude protein content of timothy (Phleum pratense L.) was investigated. Plants were grown in pots outdoors and placed in four growth chambers at different mean temperatures (8, 12, 16 and 20°C) and at three different phenological stages in order to study the interaction between temperature, development and growth. They were then harvested at weekly intervals for up to six weeks. Pots left outdoors were harvested at the same time. The dry matter yield of shoots and roots, number of tillers per plant, plant height and crude protein content in shoots and roots were recorded.

Differential response of wheat genotypes to phosphorus in acid soils

Abstract A substantial acreage of soils in northwestern Canada is acidic and P‐deficient. In this study wheat (Triticum aestivum L.) genotypes with different tolerance to acid soils were evaluated for their response to P fertility levels in greenhouse experiments. In Experiment 1, six wheat genotypes were grown on an acid soil (pH 4.8) with toxic level of Al. The Al‐tolerant genotypes included the Brazilian BH1146 and three experimental lines developed in Alberta. The soil was amended with CaCO3 to three pH levels (4.8 (untreated), 6.3, and 7.1) and with 0, 1, or 2 mmoles P/kg soil. Liming to pH 7.1 increased dry matter yields and P uptake but not liming to pH 6.3, most probably because of decreased P solubility at the lower lime rate. Consequently, yields were not correlated with soil pH. Phosphate addition increased both dry matter yield and P uptake. Shoot and root dry matter yields were positively correlated with the interaction factor P x pH but not with P alone. Differential response in this regard appeared to be related to acid‐soil tolerance. Some Al‐tolerant genotypes, such as the Alberta lines, were P efficient as measured by P uptake per g of root biomass, whereas BH1146 appeared to have a low internal P requirement combined with a relatively low shoot/root ratio. A second experiment was conducted with four acid soils (pH 5.0 to 5.8) with non‐toxic concentrations of Al and two cultivars of wheat: Laura cultivar has some tolerance to acid soil and Wildcat little. The soil treatments were combinations of unlimed or limed (pH 6.1) soil and 0, 1, or 2 mmole P/kg soil. A major objective of this experiment was to determine whether genotypes with different acid soil tolerance had different effects on soil pH and soil solution composition. Soils analyzed after crop harvest showed that Laura cultivar increased soil pH relative to Wildcat, even though plant growth was not limited by the acidic soil pH. Phosphate was effective in increasing biomass, however, and there was a genotype x P interaction. Wildcat wheat had a higher P requirement than Laura and appeared to increase its P acquisition without increasing its root growth but by lowering soil pH, thereby increasing P solubility. This relatively high P requirement and the adaptive mechanism rendered it acid soil sensitive.