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Sirvi Autor "Putniece, G." järgi

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  • Pisipilt
    Kirje
    Carbon and nitrogen accumulation by agricultural crop residue under three cropping systems
    (Estonian University of Life Sciences, 2025) Rancāne, S.; Lazdiņš, A.; Petaja, G.; Purviņa, D.; Zute, S.; Jansone, I.; Damškalne, M.; Putniece, G.
    Agricultural crops produce different biomass during their growth, including varying amounts of residue which accumulate a significant amount of carbon (C) and nitrogen (N). Assimilation capacity depends largely on species, variety and growing condition. Carbon accumulation in soil contributes to both - the agricultural production and maintenance of environmental quality reducing atmospheric C and greenhouse gas emissions. In this study, the amount of plant residue left on the field by above-ground and below-ground residue and the amount of C and N accumulated in them in three different cropping systems: organic (Bio); integrated with a low input of N fertiliser (Int-low-N) and; integrated with a high input of N fertiliser (Int-high-N) were evaluated. The most commonly grown cereal crops in Latvia were tested: winter wheat (WW); summer wheat (SW); winter rye (WR); winter triticale (WT); summer barley (SB); summer oat (SO); and buckwheat (BW) as pseudo-cereal crop. The highest biomass of dry matter of total harvest residue in all cropping systems was recorded in WR: 853.3 ± 40.76 g m-2; 1,482.0 ± 105.06 g m-2; 1,628.3 ± 115.49 g m-2 - in Bio; Int-low-N; Int-high-N cropping systems, respectively. The highest amount of carbon (g C m-2) using organic cropping system was accumulated by residue of: WR (268.6 ± 28.68), BW (239.4 ± 10.50) and WW (234.5 ± 27.41). The highest amount of carbon (g C m-2) using integrated cropping system was accumulated by residue of: WR - 473.8 ± 64.9; 496.6 ± 62.54 and WT - 458.2 ± 32.57; 521.1 ± 46.26 in Int-low-N and Int-high-N, respectively. Higher proportion of root biomass cereals formed using organic cropping system.
  • Pisipilt
    Kirje
    Estimating spring wheat nitrogen use efficiency via proximal and UAV sensing in Northwest Latvia
    (Estonian University of Life Sciences, 2026) Jansone, Z.; Bleidere, M.; Putniece, G.
    Phenotyping nitrogen use efficiency (NUE) is labour-intensive and time-consuming, often requiring destructive biomass sampling. Cost-effective sensing tools provide a promising alternative for rapid assessment of numerous wheat genotypes. In this study, sixteen spring wheat genotypes were evaluated in Latvia over three consecutive years (2021–2023) under two nitrogen fertilization levels (N75 and N150) in a split-split-plot design with two replicates, totaling 64 plots. NUE consistently differed between N rates and was strongly influenced by year-specific environmental conditions, providing contrasting scenarios for testing sensing approaches. To capture this variation, two platforms were tested for spectral estimation of NUE: a low-cost proximal phenomobile equipped with an RGB sensor, and an unmanned aerial vehicle (UAV) with a multispectral sensor. Canopy reflectance was measured at three growth stages (tillering, flowering, and milk development) to calculate 8 proximal and 9 UAV-based visible-spectrum vegetation indices (VIs). Although relationships between VIs and NUE were environmentally dependent, significant and robust correlations were found. Proximal sensing generally provided stronger prediction models, with the Normalized Green-Red Difference Index (NGRDI) and Green Area Index (GA) consistently most predictive across years. The milk development stage (GS75) proved optimal for NUE estimation. Comparisons of NGRDI between platforms demonstrated their compatibility, though UAVs offer higher throughput for large-scale phenotyping. These findings highlight the potential of integrating agronomic evaluation with canopy reflectance traits to support breeding and precision nitrogen management.