摘要:

The effects of four rates of N (0, 56, 112 and 168 kg/ha) as ammonium nitrate, with and without irrigation, on potato (Solanum tuberosumL.) leaf nutritional status at tuber initiation (t.i.) and midbloom (m.b.) were evaluated. Soil test parameters (pH, and extractable Ca, Mg, K, N) were not significantly altered by N rate. In general, leaf N concentration was increased, Ca concentration decreased, and P, K and Mg concentrations were unchanged as N rate increased. Greater changes in nutrient concentrations with time were noted as soil moisture stress was reduced. Under optimal soil moisture, concentrations of all nutrients either decreased or remained the same between t.i. and m.b. Nutrient ratios, employed by the Diagnosis and Recommendation Integrated System (DRIS) for evaluation of nutrient status, often exhibited significant changes between t.i. and m.b. across N rates, irrigation treatments and crop years. Diagnoses of the most limiting nutrients by DRIS indices were influenced by N rate, sampling period and crop year but were largely unaffected by irrigation treatment. Differential nutrient uptake and nutrient translocation during crop growth may have induced changes in elemental ratios and subsequent tissue diagnosis by DRIS between sampling periods.

ISSN:0010-3624    

DOI:10.1080/00103628909368075

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

It was proposed that the pod wall surrounding the developing soybean seed (growth stage R6) could serve as a diagnostic indicator of crop nutritional status. This was evaluated by summarizing soybean responses (R1 trifoliate and R6 pod wall P and K concentrations, and yield) to various levels of soil P and K availability in ten field experiments. Pod wall P and K concentrations were closely related to available soil P (Bray P1) and K (MNH4C2H3O2‐pH 7.0), respectively. The relationship of pod wall P concentration to grain yield was superior to those found when either trifoliate leaf P or available soil P was related to grain yield. Pod wall K was similarly superior to leaf K or available soil K. Though further work is needed to describe changes in pod wall composition during grain‐fill, it appears that pod wall sampling offers an alternative or additional sampling interval in the evaluation of soybean nutrition

ISSN:0010-3624    

DOI:10.1080/00103628909368076

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Maize (Zea maysL.) and wheat (Triticum aestivumL.) plant tissue was collected from phosphorus fertility experiments at two locations in 1985. Two samples were collected from each experimental unit and randomly either frozen immediately following collection or stored and dried normally prior to being analyzed for total P (HNO3‐HC1O4acid digest) and inorganic P (CH3COOH extract). Corn was sampled at the eight and twelve leaf stages and wheat at Feekes stage five. Freezing was accomplished using liquid N (wheat‐Feekes stage five) and dry ice (corn‐eight and twelve leaf stages). Inorganic P was found to be greater when frozen at the twelve leaf stage versus the conventional non freezing procedure. Alternatively, the opposite was found for wheat at Feekes stage five. The freezing procedure was found to increase the total P concentration for both corn at the twelve leaf stage and wheat at Feekes stage five. Losses of CO2were expected in the conventional non‐frozen samples due to an induced leaf respiration (eight hours from the time samples were collected to the time they entered the drying oven) which should have reduced dry weight and subsequently increased concentration. Because this was not found and since all other procedures employed were Identical other than freezing, it is expected that P volatilization losses must have occurred in the non‐frozen samples for corn at the twelve leaf stage and wheat at Feekes stage five

ISSN:0010-3624    

DOI:10.1080/00103628909368077

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628909368064

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor