Growth, nitrogen uptake and partitioning within the potato (Solatium tuberosum L.) crop, in relation to nitrogen application

Abstract

The effects of nitrogen applications, ranging from 0 to 25 g N/m a , on the nitrogen uptake and growth of the potato crop was studied in an experiment in both 1983 and 1984. Nitrogen uptake was substantially increased by fertilizer application. At high rates of nitrogen application, the crops took up more than was needed to satisfy their immediate requirements for growth. Initially, this extra nitrogen appeared predominantly in the form of soluble protein in the leaves and nitrate in the stem, with reduced-nitrogen in the tubers becoming a large component during tuber bulking. Application of 25 g N/m 2 increased the partitioning of nitrogen to the foliage compared with the tubers.Tuber yield was considered to be a product of four processes: radiation interception, conversion of intercepted radiation to dry matter, partitioning of dry matter between tubers and the rest of the plant and regulation of tuber dry-matter contents. Maximum tuber yields at final harvest were achieved with 15 g N/m 2 in both years. Yield increases were due to increased radiation interception, while the photosynthetic efficiency of the canopy and the dry-matter contents of the tubers were little affected. Increases in light interception, in response to nitrogen, were partially offset by a concomitant decrease in the proportion of the dry weight partitioned to the tubers, particularly during the initial period of tuber bulking. The effect of nitrogen application on tuber yield was, therefore, dependent on the date of harvest.

Effect of nitrogen application on reconstruction of nitrogen compounds during the maturation stage in several field crops

“…Since HI(N) at 300 N was lower in these crops than that at 100 N, it is considered that there was some delay in the utilization of nitrogen or in the nitrogen distribution in these crops when large amount of nitrogen were absorbed. It has been reported that nitrogen compounds with low molecular weight, such as FAA and nitrate, accumulated in plants as a result of the excess of nitrogen application (Millard 1986;Matsumaru et al 1987;Millard and Catt 1988). In the stems, the proportion of FAA-N to total-N in rice and soybean, that of nitrate-N in potato and both in wheat and maize increased with the increase of the level of nitrogen application (Table 7).…”

Yield formation and quality characteristics of early potatoes during a short growing period

“…On the other hand, oversupply of nitrogen during early growth stages causes excessive growth of the foliage, resulting in too large a canopy for optimal yield development (Krauss 1978, Kuisma 1995. Nitrogen itself has little effect on the amount of dry matter produced per unit of intercepted solar radiation (Millard and Marshall 1986). The slower canopy development of crops under low nitrogen supply can be explained mainly through reduced effi ciency of fertilizer use and decline in supply of nitrogen to the crops under cool weather conditions.…”

“…In early potato production, when tubers are harvested at low yield, low dry matter content creates a soggy texture and decreases potato quality. Under conditions of increased nitrogen supply the potato crop has the ability to take up nitrogen in excess to that required for growth and store it as nitrate in the vacuoles (Millard and Marshall 1986). Potato tubers normally have low nitrate content, not exceeding 300 mg kg -1 in fresh matter (Blom-Zandstra 1989).…”

Production efficiency of nitrogen absorbed by-potato plant at various growth stages

“…Therefore, if the nitrogen concentration of leaves remains high due to the application of a large amount of nitrogen, the photosynthetic rate is likely to remain high during growth. However it has been reported (Dyson and Watson 1971;Karauss 1978;Millard and Marshall 1986;Osaki et al 1992), that a large amount of nitrogen applied as basal fertilizer stimulated only the shoot growth, and did not affect appreciably the tuber yield. It was, thus, considered that the canopy structure and physiological conditions deteriorated by heavy nitrogen application (Osaki et al 1991).…”