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2024

Sammendrag

In the present work we have investigated the effects of abiotic and biotic factors on the growth and quality of carrots. The experiment tested how precipitation above field capacity (WATER) vs. no precipitation (DROUGHT) affect carrot growth and storability. Each treatment period lasted three weeks. We found no yield difference between the treatments at harvesting the carrots (6.6 vs. 6 t daa‑1) and the proportion of fresh roots was generally around 85%. High precipitation, especially in the latter part of the growth period, resulted in a higher proportion of cracked roots, number of roots with a lighter colour, rot in the upper part of the root and the occurrence of enlarged cork cells. After storage, we did not see any difference between the different treatments in the proportion of fresh roots. There was a slight tendency for tip rot to increase during drought at the end of the season. The soil content of phosphorous (P), potassium (K), magnesium (Mg), calcium (Ca) and sodium (Na) was reduced by high water supply, especially early in the season. The nutrient content in the roots was generally less affected by treatments than the soil mineral content. We found that the content of K and manganese (Mn) was higher at high water supply and the content of zinc (Zn) and ion (Fe) lower. The dry matter content was lowest in the treatments with a high-water supply. As the precipitation influences the soil content of some minerals, we looked at how low pH, low Ca content in the soil, would influence carrot growth. High soil pH (7.4 vs. 5.5) resulted in a higher proportion of roots with fingers when harvesting, but a lower proportion of roots with tip rot after storage (7.8 vs. 3.3%) as well as a higher proportion of healthy roots (83% vs. 67%). The conclusion is that the climatic changes where periods with high precipitation and with drought occur more often require attention to cultivation methods to reduce the negative effects.

Sammendrag

To facilitate nutrient management and the use of manure as a feedstock for biogas production, manure is often separated into a solid and a liquid fraction. The former fraction is usually high in P and low in N, so when incorporated in the soil as fertilizer, it needs to be supplemented by N from, e.g., mineral fertilizers or nitrogen-fixing species. To explore strategies to manage N with solid-separated manure, we examined how the amount of digestate and the N:P ratio of pig digestate, i.e., manure that had partially undergone anaerobic digestion, affected the productivity of Westerwolds ryegrass and red clover in a pot experiment with one soil which was rich and another which was poor in plant nutrients. The soil and plant species treatments were combined with four doses of digestate, which gave plant available phosphorus (P) concentrations of 2, 4, 8, or 16 mg P100 g−1 soil. Ammonium nitrate was dosed to obtain factorial combinations of digestate amount and N:P ratios of 1.8, 4, 8, and 16. Clover was harvested once at the beginning of flowering (15 weeks after seeding), while Westerwolds ryegrass was allowed to regrow three times after being cut at the shooting stage (in total, 4 cuts, 6, 9, 12, and 15 weeks after seeding). Ryegrass yield increased by up to 2.9 times with digestate dosage. Interactions with the N:P ratio and soil type were weak. Hence, the effect of increasing the N:P ratio was additive across digestate dosages. Red clover biomass also increased by up to 39% with digestate dosage. Residual nutrients in the soil after red clover cultivation were affected by the initial differences in soil characteristics but not by digestate treatment or biomass of harvested red clover. A targeted N management is required to benefit from the P-rich digestate in grass cultivation, while the long-term effects of red clover culture on N input need further investigation.

Sammendrag

https://ehc.usamv.ro/wp-content/uploads/2024/05/S10-Book-of-Abstracts.pdf The mid-early ripening cultivar, 'Summerred‘, is popular among consumers and widely grown in Norway. However, 'Summerred‘ fruit is prone to rapid softening and development of senescence-related disorders, especially senescent breakdown. Calcium can have a significant role in maintaining firmness and delaying senescence of fruits. In a two-year study, foliar application of calcium chloride (CaCl2) was conducted six times, with varying weather conditions between the growing seasons. Fruit was harvested at optimal commercial maturity and stored at 4 °C for either six or nine weeks, followed by simulated shelf-life conditions at 20 °C. Ethylene levels were monitored during storage to detect ripening discrepancies. At harvest, CaCl2-treated fruit exhibited significantly lower ethylene production compared to untreated fruit, although no differences were observed during the end of the storage period. Senescent breakdown showed significant variability between the two seasons, with an incidence of up to 15 % in the first season and nearly no incidence in the second season. Senescent breakdown increased with storage length but was not affected by foliar CaCl2 application. Real-time PCR analysis of fruit flesh samples revealed increased expression of polygalacturonase and β-galactosidases genes after storage, indicating their involvement in apple softening. Notably, there were no differences in gene expression between CaCl2-treated and untreated fruit after storage. Expression patterns of genes involved in ethylene biosynthesis at harvest were different between the two seasons. Higher expression was observed in the year when more disorder development occurred, indicating advanced maturity at harvest. There were no significant differences in Streif index between the two years.