Accumulation and yield formation in potato across controlled and field experiments: implications for nitrogen use efficiency research

I. Taškova¹²*, L. Rābante-Hāne¹², I. Alsiņa¹ and I. Skrabule²

¹Latvia University of Life Sciences and Technologies, Faculty of Agriculture and Food Technology, Institute of Soil and Plant Sciences, 2 Liela street, LV-3001 Jelgava, Latvia ²Institute of Agricultural Resources and Economics, Zinatnes street 2, LV-4126 Priekuli, Latvia
*Correspondence: inese.taskova@arei.lv

Abstract:

Potato (Solanum tuberosum L.) productivity is strongly influenced by nitrogen (N), which regulates plant growth, biomass formation and tuber development. This study aimed to evaluate nitrogen accumulation and its relationship with biomass and yield, and to verify nitrogen use efficiency (NUE) assessment by comparing field trials with pot and in vitro experiments. Field experiments were conducted in Priekuļi, Latvia, under organic (OF) and integrated (IF) farming systems and in vitro experiments under controlled conditions. Pot trials were carried out in Jelgava. Three varieties (‘Monta’, ‘Prelma’, ‘Jogla’) were tested. Nitrogen was applied at 60 kg N ha⁻¹ in IF field plots; pots received 60 and 120 kg N ha⁻¹, while in vitro treatments included 7.5, 20 and 60 mmol L⁻¹ N. Nitrogen content in tubers was significantly affected by growing year and variety in both field systems (p < 0.05), with a significant year × variety interaction in OF. ‘Prelma’ consistently showed the highest nitrogen content, whereas ‘Jogla’ had the lowest across systems. Yield varied substantially among years and cultivation systems. In IF, ‘Jogla’ produced the highest yield, while in OF ‘Prelma’ performed best; ‘Monta’ had the lowest yields in both systems. In pot experiments, the highest yield was obtained at 120 kg N ha⁻¹, particularly for ‘Jogla’. Nitrogen use efficiency (NUE) decreased with increasing N rate. The relationship observed under field conditions that earlier-maturing varieties have lower NUE than later-maturing ones could not be confirmed in the in vitro and pot experiments. Overall, consistent varietal responses across systems indicate that controlled-environment methods can support NUE evaluation in potato research.

Key words:

in vitro, integrated farming system, organic farming system, pot experiment, Solanum tuberosum

Effect of zeolite, clay and peat on salt stress tolerance of lettuce (Lactuca sativa L.)

A. Karlsons* and A. Osvalde

Institute of Biology, Faculty of Medicine and Life Sciences, University of Latvia, 4, O. Vaciesa Street, Riga, LV−1004, Latvia
*Correspondence: andis.karlsons@lu.lv

Abstract:

The present study aimed to investigate the effects of natural zeolite, clay and peat amendments on the growth and NaCl absorptions of lettuce (Lactuca sativa L.) under gradually increasing salinity. Four different growing media based on quartz sands with 10% additions of zeolite, clay and peat were tested. The worst effect of NaCl on plant biomass was evident at the highest salinity levels for zeolite applications. While adverse salinity impact on leaf and root biomass was least pronounced in treatments with peat additives. As expected, the lowest Na concentrations in plant tissues were found in the growing media supplemented with zeolite. In the case of Cl, however, it was the opposite – lettuce leaves accumulated significantly higher chloride concentrations in the zeolite variants in salinity treatments above 20 mM NaCl. In the control, clay and peat treatments, as the substrate salinity increased, the Cl level in the plant increased similarly. Adverse changes in leaf chlorophyll concentration (SPAD) and photosynthetic rate (µmol m^-2 s^-1) parameter appeared under salinity concentrations above 20 mM and were more pronounced in zeolite and sand substrate. According to the obtained results, peat additives can effectively mitigate the harmful effects of excessive salts by binding and immobilizing them as well as improving the water-holding capacity and nutrient availability. The study also concluded that natural zeolite successfully immobilizes cationic sodium, but the harmful effect of chlorine significantly reduced plant growth and photosynthetic performance. Clay additives to the growth medium showed the potential to reduce the adverse effects of salinity on lettuce, however, under the experimental conditions implemented, the effect was small.

Key words: