Effects of different plant density and nitrogen application rate on nitrogen use efficiency of potato tuber.
ABSTRACT In order to investigate the plant density and nitrogen level on nitrogen use efficiency components (agronomical, physiological, apparent recovery and nitrogen use efficiency), the amount of nitrogen uptake by plant, yield and yield components of potato (Solanum tuberosum L.) Agria cultivars' tuber, a factorial experiment based on randomized complete block design was conducted in Ardabil, Iran, in 2006 with three replications. Factors were adjusted for the nitrogen level (0, 80, 160 and 200 kg ha(-1) net nitrogen) and plant density (5.5, 7.5 and 11 plant m(-2)). Results showed that with increasing the nitrogen levels and plant densities agronomical nitrogen use efficiency, physiological nitrogen efficiency and nitrogen use efficiency were decreased and apparent recovery nitrogen efficiency was increased. The most nitrogen uptake in plant was observed at the 200 kg ha(-1) net nitrogen. The most yield and number of tuber per unit area were gained at the 80 and 160 kg ha(-1) net nitrogen. Increasing the plant density resulted in increasing in the tuber yield per unit area and the rate of nitrogen up to the 160 kg ha(-1) net nitrogen. So, application of the 80 kg ha(-1) net nitrogen and plant density of 11 plant m(-2) is recommended to get highest yield with the most nitrogen use efficiency.
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ABSTRACT: Root crops are an important staple food in the Pacific region. Yields are generally low and inorganic fertilizers are deemed an option to increase root crop production. The effects of inorganic N fertilizers on upland taro (Colocasia esculenta (L.) Schott) and sweet potato (Ipomoea batatas (L.) Lam.) were quantified with the aim to investigate relationships between inherent soil fertility, N uptake, N application rates and crop yield. The research took place on a sandy, Typic Tropofluvents in the humid lowlands of Papua New Guinea. Five levels of fertilizer N (0,100, 200, 300 and 400 kg ha−1) were given in split applications. The yield of marketable taro corms was not affected by N fertilizer but non-marketable corm yield doubled at high N fertilizer rates. High N applications yielded 8–11 Mg ha−1 more taro tops. Marketable and non-marketable sweet potato yield was negatively affected by N fertilizers. High N applications yielded 26 Mg ha−1 more vines than the control treatment. Nitrogen fertilizer significantly reduced the harvest index in both crops. When no fertilizer was applied, the total N uptake of taro was 32.0 kg ha−1 of which 9.7 kg was taken up in the marketable corms. At 400 kg N ha−1 the total N uptake was 67.5 kg ha−1 of which 23% was taken up by the marketable corms. Uptake of N in the marketable sweet potato tubers was less than 11 kg ha−1 and for most treatments more N was taken up in the non-marketable tubers than in the marketable yield. Up to 156 kg N ha−1 was taken up with the sweet potato vines. Despite the negative effect of N on sweet potato yield, sweet potato had a higher N use efficiency than taro due to a higher above-ground biomass production. The N fertilizer recovery was 25% for the sweet potato but only 9% for the taro indicating considerable N losses, likely caused by leaching.Agriculture, Ecosystems & Environment. 01/2000;
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ABSTRACT: The relationshops between numbers of main stems and some measures of growth and yield, as well as total tuber yield, were examined for potatoes grown under different daylengths. Leaf area, tuber number and tuber yield per plant increased significantly with increasing daylength and number of main stems. Numbers of main stems and leaf area were correlated positively with tuber number and tuber yield and negatively with average tuber weight. The correlations were stronger with stem number than with leaf area and were differently affected by daylength. Standard regression coefficients indicated that stem number has strong positive and negative relationships with tuber number and average tuber weight, respectively. Since tuber number was a better determinant of yeild than average tuber weight, the final relationship between the numbers of main stems and tuber yield remained positive for all daylengths. Determinants that will best explain variation in tuber total yield, tuber number, and average tuber weight are suggested.Potato Research 05/1990; 33(2):257-267. · 0.56 Impact Factor
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ABSTRACT: Potato (Solanum tuberosum) yield has been opti- mized for in-row spacings ranging from 15 to 40 cm depending on region, targeted market, vari- ety, and other factors. Production goals require optimizing tuber size to maximize crop value. Our goal was to evaluate the effect of plant, stem, and tuber density on stem and tuber set, potato yield, tuber size distribution, and other quality factors. Research plots were established within a 20-ha commercial production fi eld, and analysis was done with linear and nonlinear regression. Plant density decreased with increasing in-row plant spacing. Stem density increased linearly with increasing plant density, but response differed across years. Tuber density increased to a maxi- mum of 190 tubers m-2 in response to plant and stem density, with stem density more accurately predicting tuber set. Yield was related to plant, stem, and tuber density using nonlinear regres- sion, more accurately predicted by stem and tuber density than by plant density. A hyperbolic model was used to predict yield with estimated maxi- mum yield of 86 Mg ha-1 when related to stem density. Average tuber size was related to stem and tuber density using the inverse yield law and estimated maximum average tuber size of >200 g. The distribution for tuber sizes was estimated as a Weibull probability density function that pre- dicted changes in tuber size in response to stem and tuber density. The hyperbolic model accu- rately predicted tuber density and yield with the added benefi t that estimated parameters have biological importance, unlike polynomial or other regression models used to predict crop yield. Modeling tuber size distribution over different stem densities provides a mechanism for future economic analysis to optimize management and conduct sensitivity analysis to determine the most important factors infl uencing crop value.