Yazar "Gemtos, Theofanis" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim
    Öğe
    Effects of Row Spacing on Growth, Yield and Quality Parameters of Sweet Sorghum
    (2017) Cavalaris, Chris; Merkourıs, Odisseas; Karamoutis, Christos; Akdemir, Serap; Mamma, Diomi; Kekos, Dimitrios; Gemtos, Theofanis
    A two-year field experiment was conducted in Thessaly, Central Greece, in order to evaluate the effect of row spacing on several growth and yield parameters of sweet sorghum. In particular, two row spacings were tested: wide row spacing (WRS) at 0.75m and narrow row spacing (NRS) at 0.375m. During the growing period, crop growth in terms of plants' emergence, plants' height, panicle appearance, while stalk sugar content, dry biomass and total sugar yield were also evaluated. In addition, plant material was analysed to assess the potential effects of the treatments on stalk quality. The results showed that with the appropriate cultural practices, sweet sorghum can yield over 40 Mg ha-1 of dry matter and over 18 Mg ha-1 of total sugar yield under Greek conditions. Narrow row spacing resulted to higher plant population and productivity in terms of dry matter and total sugar yield (61% and 37% increase, respectively) in the first year, but without any statistical significant difference compared to the wide spacing in the second year. The compositional analysis of the crop samples revealed significant effects of row spacing on water soluble matter, cellulose and hemi-cellulose content revealing a beneficial effect of narrow row spacing on the quality and consequently ethanol production.
  • Küçük Resim
    Öğe
    Monitoring Sunflower and Maize Canopy Under Alternative Nitrogen Regimes with Lidar and Optical Sensors
    (2017) Cavalaris, Chris; Akdemir, Bahattin; Karamoutis, Christos; Gemtos, Theofanis
    Crop fertilization is an important part of cost and energy inputs in agriculture. The opportunity to apply the variable rate of nitrogen fertilizers according to the plant needs in each part of the field is a promising practice to increase the fertilizer use efficiency. An experiment was conducted in 2016 in the University of Thessaly farm, Central Greece in order to evaluate the use of lidar and optical sensors to monitor the crop canopy for sunflower and maize. The canopy development can serve as a good indicator for the nutrition state of the crops regarding especially the nitrogen, and it can be used as an indicator for variable rate application systems. In order to obtain plants with different canopy development, a field experiment was established with treatments receiving the normal, farmer's practice, nitrogen rates (100%N) at basic fertilization, treatments receiving 50% reduced nitrogen fertilizer (50%N) and treatments with no nitrogen application (0%N). During growing, the crop canopy was monitored with a lidar and an optical sensor. Manual measurements of plant height and weight were also made. The manual measurements revealed the effect of variable fertilizer rates to plant development. The plots with higher nitrogen rates had higher and more vigor plants. The lidar sensor depicted more clearly these differences compared to the optical sensor. Plant height was sufficiently assessed for both the sunflower and maize crop by lidar. Plant volume though was assessed only for the sunflower. A problem with the lidar sensor was the small sampling rate (almost 2Hz) but this can be compensated by its ability to scan simultaneously more than one crop rows (4 to 6) and obtain multiple sample information.