Browsing by Subject "yield"

Mulching, as a cultivation technique, has been adopted since the early twentieth century in agriculture for improving various aspects of crop production. However, the use of mulching was boosted by the introduction of plastic mulch, which has been reported as a harmful substance to the farm environment. Therefore, the need for an environmentally benign mulch material is obvious. The present study investigated the effects of paper and biodegradable plastic mulches on the cucumber yield, soil temperature and moisture content (at 10 cm depth), and the control of weed growth in an agricultural field located at the University of Helsinki in Southern Finland. The degradability of mulches was also investigated. The null hypothesis was that all the mulches would have a similar effect on the abovementioned aspects. Four paper mulches, i.e., BP, KB, CK, and OB, accompanied by biodegradable mulch (BIO) and a bare soil (BG) treatment were under investigation. Each of these treatments had 4 replicates, and a randomized complete block design (RCBD) was adopted. Sensors were installed at 10 cm depth in each study plot to measure the soil temperature and moisture content. In addition, the experimental plots were watered by drip irrigation. All the attained data were analyzed using SPSS statistical software. The results of the study revealed noteworthy positive effects (P<0.05) of mulch application on cucumber yields together with soil temperature, early fruiting, and weed growth regulation compared to the un-mulched bare ground, exclusive of soil moisture content. The daytime soil temperature (DST) was higher than at night (NST), indicating a positive association of the mulch effect with plant growth and crop earliness. However, no suggestive improvement in soil moisture was found through mulch application during the study period. Edge degradation was only found for paper mulches during the study period, suggesting their environment friendliness. The CK and KB papers were the most effective and most environmentally positive mulch materials, and could be a suitable choice for Finnish vegetable growers. The findings of this study could assist paper manufacturers in improving the qualities of mulch papers regarding vegetable production. Future research aims at assessing the effects of mulches on the physiology of plants studied under mulched techniques together with the development of cheaper and more environmentally benign mulch materials.

Biochars are produced from organic materials using pyrolysis and are used as a soil amendment to improve soil fertility and plant growth. Biochars are particularly beneficial to soils with high acidity, low carbon (C) content, nitrogen (N) content and other nutrient contents. However, it is not well-studied whether the beneficial effects of a biochar exist for the long-term. The aim of this study was to examine the effects of one-time application of spruce biochar on soil and barley (Hordeum vulgare L.) properties in the long-term. For this purpose, soil and plant properties were measured from the biochar field experiment in a boreal nutrient deficient Umbrisol where spruce biochar was applied eight years earlier. The experiment had a split-plot design with biochar application rates (0, 5, 10, 20 and 30 t ha-1) as the main-plot factor. The effects of fertilisers alone and their interaction with biochar were studied with three treatments (control, mineral fertiliser and meat bone meal (MBM)) as the sub-plot factor. Soil moisture content at 0–15 cm depth, as well as pH, plant available nutrients, total C and N content and C/N ratio of the soil were measured. Barley growth was assessed indirectly by measuring leaf chlorophyll content (SPAD), leaf area index (LAI), plant stand density, biomass, C and N content, C/N ratio, grain yield and weight of 1000 grains (TGW). No consistent significant effects of biochar on soil moisture content or soil chemical properties were observed. Biochar application did not have significant effects on leaf chlorophyll, leaf area index, plant density or biomass of barley. The highest biochar application rate of 30 t ha-1 tended to increase grain yield and TGW but the increases were not statistically significant. Mineral and MBM fertilisers produced similar grain yields although N was likely less available from MBM earlier in the growing season. Biochar and fertiliser interaction did not have significant effects on any of the measured properties. The lack of effects of biochar may be explained by the high amount of initial soil organic matter as well as low liming effect and low nutrient content of the used biochar. In addition, the lack of significant effects of biochar also suggests loss of biochar from topsoil due to weathering and downward displacement of biochar over the period of eight years. In this study, biochar application did not have negative consequences on the measured soil and crop properties. Therefore, it should be safe to use. Biochars may provide a viable option to sequester carbon in boreal agriculture. Further research on this is still needed to investigate the long-term effects of different types of biochars on different types of soils.

Protected cultivation of raspberries (Rubus idaeus L.) has increased its popularity in Finland. One reason is that the fruit is extremely sensitive to rainy weather during its development. The raspberry plant itself is sensitive to wind and low temperatures, which can reduce growth. In Europe most of the raspberry is grown in protected cultivation, and this technology is now becoming popular in Finland. A high tunnel is a cost-efficient way to protect the plants against rainy weather and extend the harvest season. The protected cultivation has been shown to increase the yield and cropping potential of raspberry and reduce the gray mold in the berries. In human diet, berries are among the richest sources of antioxidants. In raspberry, the most important antioxidants are vitamin C (20 %) and phenolic compounds (80 %). Among phenolic compounds, ellagitannins and anthocyanins give the greatest contribution to antioxidant activity. The aim of this thesis was to study the yield, sensory quality, nutritional quality and shelf life of three floricane fruiting raspberry cultivars grown in high tunnel and open field. Cultivars ’Glen Ample, ’Glen Dee’ and ’Maurin Makea’ were used in the study. Sugar and acid content of raspberry were examined to get an overview of sensory quality. The nutritional quality was studied with an antioxidant activity assay (using FRAP method) and total phenolics assay (using Fast Blue BB method). The shelf life was tested both in +5 °C and in room temperature. The average total yield per cane was 99 % greater in tunnel than in the open field, whereas both sugar and acid content of the berry were greater in open field. Berry weight and total phenolics content were strongly cultivar dependent characteristics. The results of the antioxidant activity assay did not show significant differences between either growing conditions or the cultivars. The shelf life in room temperature was equally weak for all samples, but in +5 °C storage the open field raspberries developed symptoms of gray mold earlier than those picked from the tunnel. The conclusion is that contents of health beneficial compounds in berries were not affected in tunnel cultivation, but berry taste may be affected, as differences in sugar and acid contents were observed.