摘要:

The heterogeneous nature of the soil of the root zone will produce wide variations in soybean (Glycine max(L.) Merrill) root development. The effects of management practices on root development are not as well understood as are the effects of cultural practices on shoot development. General descriptions of soybean root system production are presented in the literature. Evidence has also been presented in support of the concept that soybean root development is a dynamic, self regulated process, controlled, in part, by the root zone environment. Numerous quantitative and qualitative techniques have been used to haracterize field rooting patterns, and significant differences in root production and distribution have been observed among soybean cultivars.

ISSN:0010-3624    

DOI:10.1080/00103628609367753

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The volume of soil treated with P fertilizer affects P uptake by the crop. Earlier studies have shown that the stimulation of root growth in P‐fertilized soil was similar for both corn (Zea maysL.) and soybean (Glycine maxL. Merr). The objective of this research was to determine the effect of fertilizer P placement on P uptake and shoot and root growth of spring wheat (Triticum vulgareL.). Wheat was grown for 34 days in Raub silt loam (Aquic Argiudolls) in a controlled climate chamber. One rate of phosphate per pot, 150 mg P per three kg of soil, was mixed with 2, 5, 10, 20, 40 and 100% of the soil in the pot. The P was equilibrated with moist soil for 5 days at 70°C followed by 21 days at 25° C before transplanting 8‐day‐old wheat plants into each 3 L pot. The P stimulation of root growth in the P‐treated soil was similar to that for corn and soybeans. The effect could be described by the equation y = x0.7where y is the fraction of the root system in the P‐fertilized soil where P is mixed with x fraction of the soil. The greatest P uptake and plant growth occurred when added P was mixed with 20% of the soil.

ISSN:0010-3624    

DOI:10.1080/00103628609367754

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A glasshouse experiment was conducted with young grafted kiwifruit plants to evaluate a rapid sap nitrate test using Merck nitrate test strips, and to establish critical values for maximum vine growth. Total N leaf concentration for these plants was also related to vine growth. Sap nitrate nitrogen was significantly related to growth of the plant expressed as unit leaf rate (ULR) over four and six week periods from the time of sampling. Total N, on the other hand, was only significantly related to the total cane length at the time of sampling but not to the ULR. Using Cate‐Nelson graphical method, the critical sap NO3‐N value for maximum growth was established at 500–600 ppm. The critical value for total N was established at around 3.2%.

ISSN:0010-3624    

DOI:10.1080/00103628609367755

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The performance of the vanodomolybdate and molybdenum blue methods for the routine determination of phosphate in plant sap were compared in order to assess their suitability for the detection of P deficiency at an early stage of plant growth. The molybdenum blue method wasca10 times more sensitive than the vanadomolybdate one and required less sap to give a successful test. Recoveries of phosphate added to both sap and solution samples were close to 100% with both methods. The methods were in good agreement over a wide range of phosphate concentrations using sap samples from all leaves during the early stages of P deficiency, but increases in sap background colour caused the vanadomolybdate method to overestimate phosphate concentrations as the deficiency became more acute. Measurements on solutions of similar absorbance showed that the vanadomolybdate method was not significantly more variable than the molybdenum blue method but tended to overestimate phosphate concentration when very small volumes of sap were available. It was concluded that the molybdenum blue method was the most reliable for routine measurements of phosphate in plant sap.

ISSN:0010-3624    

DOI:10.1080/00103628609367756

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Data pertaining to grain yield, yield parameters, and N uptake during different periods of rice growth, in three field experiments, were subjected to the statistical procedure of path coefficient analysis. The observed grain yield response to the applied fertilizer N was predominantly reflected in an increased panicle density and spikelet number. The 1,000‐grain weight was only slightly influenced by N fertilization. Since both panicle density and spikelet number are known to be largely determined within 70 days after transplanting (DAT), N uptake during this ‐period was found to be critical to achieve a maximum grain yield response to applied N. The K uptake during 0–40 DAT correlated positively with panicle density, whereas absorption of N during 40–70 DAT determined both panicle density and spikelet number. Since N uptake during 0–20 DAT exerted a significant positive influence on grain yield through increased panicle density, the basal application of a part of fertilizer at the time of transplanting was justified.

ISSN:0010-3624    

DOI:10.1080/00103628609367757

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Leaf samples from cranberry plants in Wareham, Massachusetts were collected during the 1980–82 growing seasons and analysed for N, P, K, Ca and Mg. The seasonal patterns which emerged allowed the proposal of normal ranges for the elements and optimum times for sampling. The foliar nutrient levels obtained were compared to those for cranberries grown in other areas as well as to those for crops which are grown under similar conditions.

ISSN:0010-3624    

DOI:10.1080/00103628609367758

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The effect of soil series, cultivation, soil depth, and parent material on the correction factor which should be applied to organic carbon values determined by the method of Walkley and Black, has been examined using 450 low‐activity‐clay soil samples from high rainfall tropical Queensland. There were minimal effects due to soil depth, and differences between virgin and cultivated soils were greatest in soils formed on beach sands. However, soils formed on granitic or metamorphic rocks require a factor of 1.24, whereas the originally recommended factor of 1.32 (Walkley and Black) has been confirmed for soils formed on basalt, alluvium, and beach sands.

ISSN:0010-3624    

DOI:10.1080/00103628609367759

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628609367752

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor