A critical assessment of the value of petiole sap analysis in optimizing the nitrogen nutrition of the potato crop

Abstract

The importance of standardizing on sampling procedures was shown by examining diurnal variation of petiole sap nitrate-N concentration, [NO;-N], and its variation within the plant. There was important variability in petiole sap [NO~--N] about the general decline in values through the season, in time, between cultivars, between nitrogen fertilizer treatments, and between replicates. We have shown the lack of a consistent relation between petiole sap [NO 3-N] and rates of uptake of nitrogen either in the period around the time of sampling, or integrated over the whole growing season. Finally, we have examined the literature and have been unable to find reports of critical, independent tests of the use of petiole sap [NO~-] to guide the application of fertilizer supplements. We conclude that a new, critical attitude should be taken to testing petiole sap [NO 3 ] if the technique is to be used properly and to its seeming potential. Comparisons were made between measurements using a hand-held system and an auto-analyser.

Potato Crop Nitrogen Status Assessment to Improve N Fertilization Management and Efficiency: Past–Present–Future

“…PSNC have also been demonstrated to be more closely related to plant N-status (short-term or final N-uptake) between 20 to 60 Days After crop Emergence (DAE), with 60 to 90% of the variance accounted for (MacKerron et al 1995;Olivier et al 1999). This period also needs to be adapted according to the maturity type of the potato cultivars.…”

“…Also in Europe the PSNC test was scrutinised by several scientists (Van Loon et al 1987;Hofman et al 1995;Laurent and Lancelot 1999;Olivier et al 1999Olivier et al , 2001. A critical assessment of the PSNC test pointed out several weaknesses of the method (MacKerron et al 1995). At leaf or plant scales, several non-invasive methods reviewed by Booij et al (2000) are available or studied (e.g.…”

“…Several authors reported the seasonal trends in PSNC after a single application of various N rates (Jones and Painter 1974;Prasad and Spiers 1985;Roberts and Cheng 1988;Roberts et al 1989;Williams and Maier 1990b;Westcott et al 1991;Vos and Bom 1993;MacKerron et al 1995;Zhang et al 1996;Olivier et al 1999). However MacKerron et al (1995) identified that more nitrogen than measured could be stored in other parts of the plant (as reduced N in leaf lamina, or as nitrate in stems and lower leaves). This is due to possible luxury N taken up by the crop that would occur at the start of the season (Millard and Marshall 1986).…”

A Case Study of Potential Reasons of Increased Soil Phosphorus Levels in the Northeast United States

“…The available P can slowly be replenished but depends upon the uptake speed and behavior of the crop [42]. Once the crop absorbs the available P from the soil solution, it can slowly be replenished by the unavailable or stable form of P. The plant's ability to take up available soil P from soil solution further depends on its root distribution [42][43][44].…”

“…The available P can slowly be replenished but depends upon the uptake speed and behavior of the crop [42]. Once the crop absorbs the available P from the soil solution, it can slowly be replenished by the unavailable or stable form of P. The plant's ability to take up available soil P from soil solution further depends on its root distribution [42][43][44]. In potatoes, P is applied as a banded application for direct contact of potato roots to P fertilizer, but the amount of rainfall (Figure 7a) after planting and before potato P uptake creates a window for P fertilizer to move deeper or to be fixed in unavailable or marginally available forms.…”