摘要:

The yield response of yellow lupin (Lupinus luteus), sand plain lupin (L. cosentinii), narrow‐leafed lupin (L. angustifolius), and white lupin (L. albus) to applications of phosphorus (P), as single superphosphate (0 to 80 kg P ha‐1), was measured in the year of application in a field experiment on a sandy soil. Comparative P requirement was determined from yields when no P was applied, the amount of P required to produce the same percentage of the maximum (relative) yield, such as 90% of the maximum yield, and the P content measured in dried tops. For all these criteria, P requirement generally increased in the orderL. cosentinii < L. albus < L. angustifolius < L. luteus.Proteoid roots, found only onL. cosentiniiandL. albusplants, were probably responsible for these species using indigenous soil P and applied fertilizer P more effectively thanL. luteusandL. angustifolius.

ISSN:0190-4167    

DOI:10.1080/01904169709365332

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Endive plants (Cichorium endiviaL. var.crispumHegi) were hydroponically grown in a growth chamber to assess, 7 and 14 days after beginning of treatments (DAT), the variation of leaf nitrate (NO3) accumulation and growth during the light period in relation to both nitrogen (N) availability (8 and 16 mM) and form percentage ratio [50:50 and 0:100 ammonium (NH4):NO3] in the nutrient solution. Both 7 and 14 DAT, fresh weight and leaf area linearly increased during the light period without influence of N treatments. Dry matter (d.m.) percentage increased over the 12 hours of light. Leaf NO3concentration decreased during the light period more with 50:50 than with 0:100 NH4:NO3ratio: 7 DAT NO3decreased by 25% with the former N treatment and only by 4% with the latter. After 7 days more, the difference between the two N form ratios was more evident: NO3decreased by 12% with the mixed N form, while increased by 10% with 100% NO3‐N in the nutrient solution. Nitrate leaf concentration was higher with 16 mM compared to 8 mM of NO3‐N (11.3 and 8.5 g/100 g of d.m., respectively, 14 DAT). Total N leaf content was higher with 16 than with 8 mM of NO3‐N in the nutrient solution and was not influenced by the two N form ratios. Chloride (Cl) leaf concentration was higher with 8 that with 16 mM of N and more with the 50:50 than 0:100 NH4:NO3ratio.

ISSN:0190-4167    

DOI:10.1080/01904169709365333

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Phosphorus (P) deficiency is a principal yield‐limiting factor for annual crop production in acid soils of temperate as well as tropical regions. The objective of this study was to screen nine corn (Zea maysL.) genotypes at low (0 mg P kg‐1), medium (75 mg P kg‐1), and high (150 mg P kg‐1) levels of P applied in an Oxisol. Plant height, root length, shoot dry weight, root dry weight, shoot‐root ratio, P concentration in shoot and root, P uptake in root and shoot, and P‐use efficiency parameters were significantly (P<0.01) influenced by P treatments. Significant genotype differences were found in plant height, shoot and root dry weight, P uptake in root and shoot, and P‐use efficiency. Based on dry matter production and P‐use efficiency, genotypes were classified as efficient and responsive, efficient and nonresponsive, nonefficient and responsive, and nonefficient and nonresponsive.

ISSN:0190-4167    

DOI:10.1080/01904169709365334

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Plant nutrient deficiencies are the main yield‐limiting factors in highly weathered acid soils around the world. Five greenhouse experiments were conducted on an Oxisol to identify nutrient deficiencies in common bean, upland rice, corn, wheat, and soybean. The treatments consisted of 13 fertility levels including an adequate level and remaining without application of one of the essential plant macro‐ or micronutrients. Dry matter yield of tops of all the crop species was affected by fertility treatments; however, significant effects of treatments were obtained in the case of common bean, upland rice, and corn. Based on tops dry weight under different treatments compared to adequate fertility level (AFL), the most yield‐limiting nutrients were in the order of phosphorus (P) > calcium (Ca) > magnesium (Mg) > boron (B) > zinc (Zn) for common bean, P > molybdenum (Mo) for upland rice, and P for corn. For the wheat crop, there was substantial decrease in tops dry weight in the absence of Ca, P, and potassium (K) nutrients. In the case of soybean, substantial tops dry weight reduction was due to deficiency in the order of P >Ca>Zn.

ISSN:0190-4167    

DOI:10.1080/01904169709365335

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Studies on the effects of salinity and nitrogen (N) fertilization on ionic balance, biomass, and organic N production of annual ryegrass (Lolium multiflorumLam.) were conducted. Plants grown in sand were irrigated with nutrient solution with an electrical conductivity of 2 or 11.2 dS#lbm‐1, and N in the form of sodium nitrate (NaNO3), ammonium nitrate (NH4NO3), or ammonium sulfate [(NH4)2SO4] ranging from 0.5 to 9.0 mM. Salinity increased the concentration of total inorganic cations (C) in plants and specifically sodium (Na) by more than 3‐fold higher in plants grown at high salinity as compared with plants at low salinity. Sodium (Na) concentration in roots was higher than in shoots irrespective of the salinity level, suggesting a restriction of Na transport from roots to shoots. The concentration of total inorganic anions (A) increased with salinity and when plants were supplied with nitrate (NO3), salinity increased the concentrations of NO3and chloride (Cl) in plants. Increasing salinity and N concentration in the growth medium increased organic anions concentration in plants, estimated as the difference between C and A. The effect of different N sources on C‐A followed the order: NH4NO3> NO3> ammonium (NH4). The base of organic anions and inorganic ions with salinity contributed significantly to the osmotic potential of plants shoots and roots. Changes in C affected N and organic acids metabolism in plants, since C were highly correlated (p=0.0001) with C‐A and organic N (Norg) concentrations regardless of the salinity level or N source in the nutrient solutions. A high and positive linear dependency was found between Norgand C‐A in plants grown at high and low salinity levels and different N sources, pointing out the close relationship between Norgand organic anions on metabolism under these conditions. The amount of biomass produced was correlated positively with organic anion concentration in plants exposed to different salinity levels. Plant biomass increased with N concentration in the nutrient solution regardless of the salinity level applied. Biomass accumulation decreased while Norgconcentration increased with salinity. Organic N content remained unaffected in plants exposed to salinity when grown in N less than 9.0 mM.

ISSN:0190-4167    

DOI:10.1080/01904169709365336

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

HiMag is an experimental cultivar derived from Missouri 96 (Mo96) and Kentucky 31 (K31) tall fescue (Festuca arundinaceaSchreb.) parentage for increased calcium (Ca), magnesium (Mg), and reduced potassium (K)/ (Ca+Mg). Our objective was to determine productivity and mineral characteristics of endophyte‐free (E‐) HiMag in relation to standard tall fescue cultivars when grown in the Southern Piedmont Land Resource Area. In experiment 1, HiMag (E‐) and K31 (E‐) were grown at two levels of phosphorus (P), K, and lime additions to both severely eroded, and non‐eroded Cecil soil (clayey, kaolinitic, thermic family of Typic Hapludults). Herbage Ca and Mg were greater and K/(Ca+ Mg) and yield were less for HiMag than for K31. Phosphorus and K concentrations were not different. Herbage yields, P, Ca, and Mg concentrations were increased by P, K, and lime additions. In experiment 2, HiMag(E‐), K31(E‐), endophyte‐infected K31(E+), Mo I(E+), Mo II (E+), and AU Triumph (E‐) were planted either in a prepared seedbed or planted without tillage into the Cecil soil. HiMag yields were not different from Mo‐I, Mo‐II or K31(E±), but were less than those of AU Triumph (E‐). HiMag yield response to no‐till planting, past soil erosion, and fertilizer level was similar to that of K31 (E±). Fertilizer level, and soil condition affected the magnitude of differences in mineral levels in HiMag and K31 (E±), but K/(Ca+Mg) values were more favorable in HiMag. All tall fescue cultivars established equally well in no‐till or prepared seedbeds. Aside from a slightly lower first harvest yield there were no important effects of planting no‐till versus planting in a prepared seedbed. HiMag's agronomic attributes, while not superior to other cultivars, were sufficient to justify further testing to improve Mg nutrition of grazing animals.

ISSN:0190-4167    

DOI:10.1080/01904169709365337

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Potatoes (Solarium tuberosumL.) and carrots (Daucus carotaL.) were grown in the field on Tasmanian ferrosols (humic eutrudox) which had been limed either 2, 3, or 5 years earlier, and where tuber cadmium (Cd) concentrations in potatoes grown a few months after the liming had shown no lime response. In the current crops lime decreased potato tuber Cd by about 30% and carrot root Cd by about 50%. We attributed the decrease to more even and deeper mixing of the lime with the soil by the harvest of the first potatoes. Phosphorus (P) fertilizer residues from the earlier potato crops did not significantly affect tuber or root Cd, but there was a positive effect at 1 site where some high Cd P fertilizer had earlier been used. Neither lime nor P fertilizer residues affected potato or carrot yields. Analysis at one site of potato tubers from the upper part of the soil ridges showed that they had slightly higher Cd concentrations than did deeper tubers near the fertilizer band, whether P fertilizer was in the band or not. This suggests that either the Cd in the fertilizer band was relatively unimportant as a Cd source for the current crop, or that Cd was redistributed within the plant during the season, or both. Liming may be a suitable medium to long‐term strategy for decreasing Cd uptake by root crops, but site to site and seasonal variation can still be great, and knowledge of other major influences is needed for assurance of produce quality. Our observations need to be extended to sites which gives rise to higher Cd concentrations in agricultural produce, and to other soil types. Potato common scab was severe in the limed plots at one site. However, this site had grown 3 potato crops in 5 years, which probably exacerbated the disease. Potato processors in Tasmania demand a minimum of 5 years between successive crops which should slow any build up of scab due to liming, but more work on possible interactions between lime and rotation length on scab incidence is needed before liming can be recommended as a Cd control measure for potatoes.

ISSN:0190-4167    

DOI:10.1080/01904169709365338

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The main objective of this study was to examine the chemical composition of incident rainfall, throughfall, and stemflow from canopies of ‘Marsh’ grapefruit, and ‘Hamlin’ and ‘Temple’ orange trees. The concentrations of ammonium (NH4) and nitrate (NO3) were lower in the throughfall under the canopy or along the dripline as compared to those in the incident rainfall. This reduction is due to absorption of those nitrogen (N) forms by the tree foliage, thus, provides an evidence of contribution of (N) through wet deposition to N requirement of the trees. In contrast, concentrations of potassium (K), calcium (Ca), magnesium (Mg), and chloride (Cl) were greater in the throughfall or along the dripline compared to those in the incident rainfall. This is due to possible leaching of those elements from the foliage by the rainwater. Stemflow and throughfall also had greater pH and electrical conductivity (only in two out of three citrus varieties) as compared to the incident rainfall. Good correlation were found between concentrations of either K, Mg, or Ca, and Cl, phosphorus (P), or sulfur (S) in the incident rainfall for two storm events.

ISSN:0190-4167    

DOI:10.1080/01904169709365339

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

To investigate the relationship between rice genotypic variation in tolerance to iron (Fe) toxicity and nutrient element status, 10 rice genotypes with different growing performances under Fe toxicity were grown under normal culture solution and with excessive ferrous (Fe2+)‐Fe concentrations of 250 and 500 mg Fe2+L‐1. A close relationship was obtained between the relative ratio of symptomatic leaf numbers to total leaf numbers (SLN/TLN) and a relative decrease in dry matter under Fe2+‐toxicity conditions. The genotypic variations in nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg) uptake were evaluated by the relative decrease in the N, P, K, and Mg content in the plants. Remarkable genotypic variation in tolerance to excessive Fe2+was observed. The results indicated that excessive Fe2+reduced N, P, K, and Mg uptake. The nutrient element concentrations, however, were still higher above deficient criteria even in severely affected plants, suggesting that the retardation of growth may not be intirely due to the deficiency of these elements in plants at the seedling stage. Significant correlations were found between the genotypic variation and the decrease in N, P, K, and Mg uptake and in their tolerance to Fe2+toxicity, which suggests that the ability to maintain higher nutrient element uptake under a Fe2+‐toxic condition contributes the tolerance to Fe2+toxicity.

ISSN:0190-4167    

DOI:10.1080/01904169709365340

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Management decisions affecting wheat (Triticum aestivumL.) yield include nitrogen (N) fertility rate, cultivar selection, and fungicide application. Since these cultural practices may interact with each other and the environment, often times affecting grain yield, test weight, and disease development, they need to be better defined for wheat production in for the Gulf Coast region. Field experiments were conducted to evaluate the effect of N rate, fungicide, and cultivar on grain yield, test weight, and disease development. Three N rates (67, 101, and 134 kg#lbha‐1), two fungicide treatments (no‐fungicide control and fungicide), and four high‐yielding wheat cultivars with different levels of resistance to leaf rust (Puccinia reconditeRob. ex f. sp.tritici) were evaluated in 12 Louisiana field environments. Environment and interaction between environment and N rate, fungicide, and cultivar were significant for grain yield, leaf rust ratings, and test weight. Grain yield response to N rate was linear in five environments and quadratic in five environments. Although there was little evidence of a N x fungicide interaction for grain yield, increasing N rates increased leaf rust severity. Grain yields were increased by fungicide application in only four of twelve environments with a significant cultivar x fungicide interaction for grain yield. Grain yield increase from foliar fungicides was related to leaf rust severity and resistance of cultivars to leaf rust. Test weight was increased due to N in three environments and decreased in two environments. Test weight increased with fungicide application and varied among cultivars. The findings indicate that 101 kg N ha is probably adequate for maximum yield in most years. Although the higher N rates may increase yield in some years, disease pressure and the need for fungicides may also be increased.

ISSN:0190-4167    

DOI:10.1080/01904169709365341

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor