摘要:

Several different organisms cause corn(Zea mays, L.) root rot. The extent of damage to the root system varies with the aggressiveness of different causal organisms or different strains of the same causal organism. The attack of the roots by disease organisms could cause changes in the tissue analysis that would lead to misdiagnosing the cause of the problem. Studies were conducted to ascertain changes in selected mineral concentrations in the corn tissue and in plant growth resulting from various degrees of root rot caused by root infections of several different soil borne pathogenic fungi. Thermally pasteurized soil was placed in pots and infested with various fungi isolated from root lesions on corn from field studies. Corn was grown in the infested soil for four weeks in the greenhouse. Plants were harvested, roots indexed for disease, above ground visual symptoms noted, dry weight taken, and tissue analyzed for Ca, Mg, P, and K. Results showed that aerial plant parts of infected plants may exhibit typical nutrient deficiency symptoms which are not necessarily reflected in the mineral analysis of the tissue. Elemental uptake and tissue concentration appeared not to be related to changes in mineral analysis regardless of the relative soil mobility of the nutrient. Related fungi did not cause similar changes in mineral tissue concentration for the same or different minerals. Dry matter yields were reduced about 20% for each unit increase in root disease index. The use of the root disease index appears to have potential as a diagnostic tool and should be evaluated for this purpose.

ISSN:0010-3624    

DOI:10.1080/00103627809366865

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A problem pistachio orchard near Athens, Greece had many trees with severely scorched leaves. Half or more of each leaflet v/as brown and dry but tips and edges were most affected. Affected leaves were also of lighter green color than normal leaves and slightly resembled Fe deficiency. Leaf analysis indicated low K, low Fe, and high Mg. Irrigation water contained moderate levels of Mg and Na chlorides and chloride toxicity was possibly another factor. Improvement was observed when Fe chelate was appliedto theorchard but Mg‐induced K deficiency was possibly a major factor. Response to K applied to soil was not observed after four months, however.

ISSN:0010-3624    

DOI:10.1080/00103627809366866

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

This investigation reports the uptake of S from a surface application of35S‐labelled gypsum by a ryegrass‐white clover mixture sward and by a pure ryegrass stand, each growing at three levels of N in the field. Nitrogen stimulated ryegrass growth, reducing the contribution of white clover to the total yield, whereas S did not influence the yield of either species. Gypsum, while not increasing the total S in the white clover, contributed 23 to 50% of the total S concentration. In contrast, gypsum increased the total S in the ryegrass. The level of N nutrition did not alter the fertiliser S in white clover, but depressed the total S in the ryegrass. Nitrogen enhanced the fertiliser S in ryegrass at the first harvest, however, at the second harvest N depressed the fertiliser S.

ISSN:0010-3624    

DOI:10.1080/00103627809366867

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The relative merits of three acrylic based resins, cured either chemically or by gamma radiation, are examined for use in the impregnation of soils for thin section analysis. The effect of several soil variables (moisture content, pH, texture, presence of expanding minerals or transition metals) upon these resins is discussed to aid in the selection of a suitable resin for the impregnation of various soils.

ISSN:0010-3624    

DOI:10.1080/00103627809366868

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Twenty sweet corn tissue samplings were made from ten field trials during 1974–76. Fertilization had little effect on yields, but a good relationship was found between yields and leaf tissue nitrate and potassium concentrations, in the leaves 40–50 percent developed at the F‐9, F‐13 and F‐14 vegetative stages. The lower and upper tissue nitrate and potassium concentration limits (deficiency and excess) were found to range between 2000 and 3000 ppm nitrate, and 1.5 and 4.2 percent, or 2.0 and 3.25 percent potassium, according to their vegetative development. Excessive nitrogen and phosphorus application decreased kernel tenderness and total solids (sugar) content, but potassium fertilization enhanced total sugar accumulation.

ISSN:0010-3624    

DOI:10.1080/00103627809366869

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Twenty‐nine soil samples representing 12 soil series and varying levels of P fertility were obtained from cooperating agricultural experiment stations in the southern U.S. Fertilizer P requirements were estimated from P sorption curves and correlated with P requirements established by field experiments. Estimated and measured P requirements were highly correlated (r =0.93**) with the quantitative relationship being nearly 1:1. With one exception, P sorption also accurately estimated needs of fertilized soils; in that one case, fertilizer needs were estimated at 45 kg P/ha although there was no response to P in the field.

ISSN:0010-3624    

DOI:10.1080/00103627809366870

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Negative yield responses are common when highly leached soils are limed to neutrality. A number of explanations have been proposed, but very few have been experimentally verified or are entirely acceptable. In this paper the problem is re‐examined and a new possible causal mechanism is proposed.

ISSN:0010-3624    

DOI:10.1080/00103627809366871

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The relation between Mo concentration of several tropical pasture legumes and their growth response to Mo application has been compared. Lotononis had the greatest ability to take up Mo and its growth was least responsive to Mo application. There were no consistent differences between Mo concentrations in Siratro, desmodium and glycine, even though their growth responses differed.

ISSN:0010-3624    

DOI:10.1080/00103627809366872

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103627809366864

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor