摘要:

Ten‐day‐old seedlings of six rice (Oryza sativaL.) cultivars were grown hydroponically for 30 days in a nutrient solution containing 222 μM aluminum (Al)/L. Leaf reflectance properties were determined at visible (400–700 nm) and near infrared (700–1100 nm) wavelengths under controlled environmental conditions. For the Al‐tolerant cultivars of rice, there was no significant difference in the visible and near infrared reflectances. By contrast, the Al‐susceptible cultivars showed a prominent increase in reflectance in both the visible (with minor shift in the peak) and in the near infrared region. Foliar chlorophyll content decreased significantly in the Al‐susceptible cultivars but not in the Al‐tolerant cultivars. Further, mineral uptake, uitilization efficiency, and pigment contents have been correlated with these reflectances. In addition, there was no correlation between foliar Al content and changes in the reflectance of the Al‐treated susceptible cultivars.

ISSN:0190-4167    

DOI:10.1080/01904169409364775

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Intercropping millet with cowpea is a widespread practice throughout the semi‐arid regions of West Africa. Low soil phosphorus (P) is one of the main limiting factors for crop production in this region. The objective of this study was to determine optimum methods and rates of P application to a millet/cowpea intercrop on a sandy, dunal soil of western Niger. Triple super phosphate was applied by three different methods: broadcast, in millet hills, and in cowpea hills. Three rates (0, 22.5, and 45.0 kg P/ha) were applied by each method. Treatments were replicated four times in a randomized complete block design. Cowpea yields were not affected by P applications, but millet yields were maximum with 45.0 kg P/ha applied to the millet hills. The 45.0 kg P/ha broadcast and millet hill applications resulted in significantly higher leaf P levels for millet, but no significant differences were found in cowpea leaf P levels. The 45.0 kg P/ha treatment applied to millet hills also resulted in the maximum P uptake, greatest biomass production, and highest economic yield. However, P use efficiency was higher in the treatment with 22.5 kg P/ha applied to the millet hills. Phosphorus management systems must be developed which optimize yield and economic return, as well as nutrient and water use efficiencies.

ISSN:0190-4167    

DOI:10.1080/01904169409364776

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

No‐till management systems have been reported to reduce nonpoint source (NPS) pollution from agricultural fields. However, questions have been raised concerning the fate of nitrogen (N) in these systems. Increased moisture conservation and reduced runoff from no‐till systems have the potential to accelerate leaching of nitrate (NO3‐) out of the root zone, thus altering the problem from one of surface water degradation to one of ground water pollution. However, it is also probable that the additional moisture conserved in no‐till systems result in increased crop yield and N uptake. Time of N application and source of N could influence yield and N recovery and thus limit N losses during critical periods. A 3‐year study was conducted to determine if the fate of N applied to nonirrigated corn (Zea maysL.) would be influenced by tillage system, N rate, and time and source of N application. This paper addresses the impact of these practices on yield and N uptake. The experimental site was located on a Typic Hapludult that is characteristic of finer‐textured soils used for continuous corn production. Management practices evaluated were conventional‐till vs. no‐till, rate of N application, inorganic N vs. sewage sludge N, and preplant vs. split application of N.

ISSN:0190-4167    

DOI:10.1080/01904169409364777

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The nature of copper (Cu) toxicity on the growth, and pigment, and element composition of a Cu‐tolerant ecotype ofSilene compactaFischer was investigated in nutrient solution. The most evident Cu effect was on root growth. Since for plants grown under lower Cu concentrations (4 and 8 μM), root elongation, and chlorophyll, and elemental [Cu, iron (Fe), calcium (Ca), and potassium (K)] contents were increased as compared to that of the control, the development of an adaptive mechanism byS. compactato Cu is suggested. Higher Cu concentrations (80 and 160 μM) resulted in a significant reduction in root growth and an significant chlorophyll loss. Yet at the 160 μM Cu‐treatment, changes in elemental content of the plant tissues were observed. External Cu had a negative influence on the concentration of Ca, Fe, and K and a positive influence on the Cu concentration in the plant tissues. Our results demonstrate the existence of an adaptive mechanism ofSilene compactocat low Cu concentrations, but when at excessive quantities, results in severe injury to plant functions.

ISSN:0190-4167    

DOI:10.1080/01904169409364778

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Iron (Fe)‐deficiency symptoms are observed on some genotypes of lentil (Lens culinarisMedikus) grown on high pH and calcareous soils. Ten lentil cultivars/lines differing in response to Fe‐deficiency chlorosis (FeDC) were grown on a high pH (8.0), calcareous (38% calcium carbonate equivalent in surface 20 cm) and silty clay soil in the field (Beka'a Valley), to determine the effects of FeDC on seed and straw yield of cultivars/lines sprayed with Fe. A significant interaction (P<0.05) between cultivars/lines and Fe‐spray treatment was noted for visual FeDC ratings, and no significant interactions for these treatments were noted for seed and straw yields. Sprayed cultivarsAines generally produced higher straw yields than unsprayed ones. Overall increases were 38%. Even though only slight FeDC was noted on some cultivars/lines receiving no‐Fe spray, straw yields were significantly increased when sprayed with Fe. Spraying cultivars/lines with Fe did not show a significant increases in seed yield. Indicating that Fe‐deficiency chlorosis in the Mediterranean region may be a serious limitation to straw yield, but it is not to seed yield, in the existing land races and cultivars of lentils.

ISSN:0190-4167    

DOI:10.1080/01904169409364779

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The effect of cadmium (Cd) on nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na) and the micro‐nutrients iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and boron (B) on tomato plants was studied. Two Cd treatments were imposed by adding 10 or 30 mg/L Cd to the culture solution as cadmium chloride (CdCl2). The nutrients mainly affected by these Cd treatments were P, K, Fe, Mn, and Zn in the roots and stems and also P and Mn in fruits. Their absorption and/or translocation could be impeded by Cd. Yield was also diminished but not the mean fresh weight of fruit. Plant growth was affected negatively by Cd, root and stem length and fresh weight decreasing with each increment of Cd added to the nutrient solution.

ISSN:0190-4167    

DOI:10.1080/01904169409364780

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Winter wheat was grown in Mitscherlich pots on soils obtained from 12 sites from the provinces of Salamanca, Valladolid, and Zamora (Spain). The plants were fertilized with combinations of nitrogen, phosphorus, and potassium, and the crop was watered as necessary. Plants were harvested at flowering and were divided into leaves, ears, and the remaining above‐ground parts. Dry weight was recorded and the mineral content determined. The relationships between nutrient content and dry matter production were fitted by nine functions: quadratic, square‐root, inverse in x, inverse in y, inverse in both variables, and the straight line. Analysis showed that a square‐root function fitted the relationship between mineral content and dry matter production in the different parts of the plant better than the other equations. The quadratic function was also frequently significant and had large coefficients of correlation. However, the parameters of the square‐root functions had smaller standard than the quadratic, especially for the intercept. Leaf nitrogen, calcium, and magnesium, shoot nitrogen, calcium, and potassium and ear nitrogen, potassium, and magnesium contents were well fitted by the square‐root or quadratic functions, but the relationship between phosphorus content and dry matter showed a dilution effect which was fitted best with the logarithmic function on y, although the levels of significance were not large.

ISSN:0190-4167    

DOI:10.1080/01904169409364781

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Aubergine plants (Solanum melongenacv. Bonica) were grown under controlled greenhouse conditions on a soil substrate supplied with organic fertilizers (15 kg/m2) mixed with calcium sulfate (CaSO4at 500 g/m2), with different doses of nitrogen (N as N1= 15, N2= 22.5, N3= 30 g/m2) in the form of ammonium nitrate (NH4NO3), and phosphorus (P as P1= 24, P2= 36 g/m2) as phosphorus acid H3PO4). Plants were sampled every 15 days, and the pigments chlorophyll a, chlorophyll b, total (a+b) and ratio (a/b), carotene, licopene, and anthocyanins were determined in the leaves. The results showed that increases in rhizosphere N led to increases in foliar concentrations of chlorophyll a and b, both individually and as total chlorophyll, independently of the dose of P applied. Total chlorophyll concentrations were directly correlated with the level of P fertilization. Carotene and licopenes reflected the influence of increasing doses of N, whereas P did not affect these pigments. Anthocyanin levels were affected by both N and P.

ISSN:0190-4167    

DOI:10.1080/01904169409364782

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A histological method and elemental analysis were applied to study the reaction of soybean (Glycine max(L.) Merr.), cultivar ‘Maple Arrow’, to high manganese (Mn) supply under various growth conditions. The main impact of Mn toxicity was seen on the above ground parts of the plant. The brown fleckes on the old leaves and young apical crinkle leaf with chlorotic spots was identified as typical Mn toxicity symptoms. The chloroplasts of the Mn‐toxic plant cultivated in the growth chamber accumulated large starch granules, which on the contrary represented an intensive growth of the plants grown in the greenhouse. Leaf Mn content of 2.80 mg/g did not decrease the dry weight of the older leaves, but 1.53 mg/g depressed severely that of the young leaves. The dry weight of pods was also significantly decreased.

ISSN:0190-4167    

DOI:10.1080/01904169409364783

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Starking apple trees on M793 rootstocks were grown in a low phosphorus (P) soil treated prior to planting in 1982 with different rates of P (as superphosphate) and, commencing three years after planting, nitrogen (N) as limestone ammonium nitrate (LAN). The object was to improve vigour, yields, and ftuit quality. Trunk circumferences increased progressively with superphosphate application rates up to 4,730 kg/ha. Susceptibility to bitter pit also increased as did fruit size, and leaf P and magnesium (Mg) levels. Some improvements in colour were also apparent. Yields increased at superphosphate applications up to 2,240 kg/ha, but at 4,730 kg/ha were little different to the yields at 2,240 kg/ha. Leaf potassium (K) tended to decrease with increasing rate of applied superphosphate. The levels of Bray 2‐extractable P in the soil decreased with time. Reapplying superphosphate to the 0, 1,180, and 2,420 kg/ha treatments at the rate of 1,286 kg/ha in 1989 resulted in some of the differences between the initially applied superphosphate treatments becoming non‐significant. No interaction between N and P was observed, and there were no consistent, significant differences between treatments which received 110 kg LAN/ha at full bloom, 50 kg LAN/ha 40 d after full bloom, and 110 kg LAN/ha post harvest and treatments which received LAN at double these rates. In the 1989/90, 1990/91 and 1991/92 seasons, the LAN application rates in the low and high N treatments were reduced to 80, 40, 80, and 160, 80, 160 kg/ha at full bloom, 40 d after full bloom and post harvest, respectively. In 1991 and 1992, leaf and fruit N contents were significantly lower in the 80, 40, and 80 kg LAN/ha treatments than in the 160, 80, and 160 treatments. The incidence of bitter pit was lowest in the higher N treatments. Under South African orchard conditions, Starking apple trees appear to require a Bray 2‐extractable soil P level of 30–40 mg P/kg. Applications of LAN equivalent to 160 kg/ha at full bloom, 80 kg/ha 40 d after full bloom, and 160 kg/ha after harvest would appear to be sufficient for a 25 t crop.

ISSN:0190-4167    

DOI:10.1080/01904169409364784

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor