Recent years have seen a significant increase in weather anomalies in Central Europe (51°22′ N, 22°64′ E), which makes it more difficult to predict yields of winter wheat and to estimate prices on world exchanges. Eight-year (2007–2015) field observations of winter wheat cv. Turnia were carried out in order to determine the relationship between selected meteorological indicators (e.g., the values of average daily air temperature, daily sums of precipitation, and the number of days with precipitation) and the biometric traits and seed yield of winter wheat. In addition, an attempt was made to identify the meteorological parameters that determine an increase in stem elongation during the growing season. The relationship between yield parameters and biometric parameters was evaluated using Spearman’s non-parametric correlation coefficients. The regression models for analysis of the dependence of yield parameters and biometric parameters on meteorological elements (temperature, precipitation totals, and days with precipitation) in each development period was used. The study showed that from the beginning of vegetative growth to the flowering stage, growth and development were most advanced in plants for which the average temperature was about 8–9 °C, and the number of days with precipitation was about 41. During generative growth, spike length is 80% determined by the precipitation total. Grain weight is 68% negatively determined by the temperature during dormancy (the higher the temperature during dormancy, the lower the weight of the kernel). A positive relationship was shown between yield and the precipitation total during the period from sowing to the onset of dormancy (r = 0.37). Winter wheat yield was 69% dependent on the density at harvest (the greater the density, the higher the final yield). On the basis of the 8-year results of the study, we conclude that the weather is highly variable from year to year, and therefore breeders should direct their research towards creating variants with much greater plasticity and high tolerance for unfavourable weather patterns.

In this work, an attempt was made to use the WOFOST (WOrld FOod Studies) model to simulate the potential and water-limited yield of early potato cultivars Lord and Denar. Data from cultivar experiments carried out at the Polish Research Centre for Cultivar Testing in 2004–2013 were used in the study. The Lord cultivar yielded 22.4–67.8 t fresh tuber weight per ha and 3.8–11.5 t ha⁻¹ dry tuber weight during the study period. The highest tuber yields (over 10 t ha⁻¹ dry weight) were obtained in 2009, 2011 and 2012, and the lowest in 2005 (3.8 t ha⁻¹) and 2006 (2.65 t ha⁻¹). The water-limited tuber yield simulated by WOFOST ranged from 3.6 to 10.9 t ha⁻¹ dry weight and was about 0.45 t ha⁻¹ higher on average than the actual yield. The planting period each year was between days 104 and 120 of the year, and harvesting took place between days 216 and 232. Water availability was a factor limiting the yield. The yield limited by water deficiency was 38.7% lower (irrespective of the cultivar) than the potential yield. The WOFOST model was sensitive to water deficiency, and the simulated (water-limited) yields were close to the actual yield or showed a clear downward trend indicating evident rainfall shortages in 2005 and 2006.

Various devices and applications are used for the rapid assessment of plant nitrogen nutrition, which give an approximate indication of leaf chlorophyll saturation by giving the relative chlorophyll content or leaf greenness intensity. In this study, chlorophyll content and leaf greenness determined by three devices were compared: SPAD-502 (spectrum technology), Hydro N-Tester, and Samsung smartphone (RGB app). Additionally, laboratory determination of chlorophyll content was compared to soil-plant analysis development (SPAD) values. Based on the results obtained, indices characterising the vegetative or direct state were calculated and the values obtained with these devices were compared. The crops tested were soya, potatoes, wheat and sunflower. The results show a close relationship between the size of the SPAD index and RGB light sources of colour the intensity of red (R), green (G) and blue (B). The indices IPCA and R+G–2B showed a very high negative correlation with SPAD readings (−0.82 and −0.83). Statistical analysis showed that SPAD readings obtained from the two chlorophyll meters showed a high correlation regardless of the crop species tested (R2 = 0.98). The correlation analysis also showed the possibility of substituting equipment and vegetation indices based on readings taken with a smartphone, with an accuracy not much inferior to standard chlorophyll meters. This situation could occur in case of failure or absence of the standard device.

Remote sensing methods based on UAV and hand-held devices as well have been used to assess the response to nitrogen and sulfur fertilization of hypoallergenic genotypes of winter wheat. The field experiment was conducted using the split-split-plot design with three repetitions. The first factor was the two genotypes of winter wheat specified as V1 (without allergic protein) and V2 (with allergic protein), and the second factor was three doses of sulfur fertilization: 0, 20 and 40 kg S per ha. The third factor consisted of six doses of nitrogen fertilization: 0, 40, 60, 80, 100 and 120 kg N·ha⁻¹. Monitoring the values of the indicators depending on the level of nitrogen and sulfur fertilization allowed the results to be used in yield forecasting, assessment of plant condition, LAI value, nutritional status in the cultivation of wheat. The maximum yield should be expected at doses of 94 and 101 kg N ha⁻¹ for genotypes V1 and V2, respectively, giving yields of 5.39 and 4.71 Mg ha⁻¹. On the basis of the tested vegetation indices, the highest doses of N should be applied using the normalized difference RedEdge (NDRE), and the lowest ones based on the enhanced vegetation index (EVI), and, in the latter case, a reduction in yield of more than 200 kg ha⁻¹ in the V2 genotype should be taken into account.

Yield and the course of crop vegetation are the result of the interaction between the level of cultivation technology and the course of meteorological conditions, which are a variable production factor. The aim of the study was to quantify the effect of meteorological conditions on the course of development stages and yield of winter wheat cultivated in two technological variants (A1 – medium-intensive and A2 – intensive). The paper uses data on yield and timing of winter wheat development stages from four Experimental Stations for Variety Testing (Pol. Centralny Ośrodek Badania Odmian Roślin Uprawnych – COBORU) experimental stations from 2007–2016 located within the Upper Vistula and Upper Oder River basins. To determine the dependence of the length of development stages of winter wheat on the values of selected meteorological elements, the linear regression metod, correlation coefficient. It was found that the lengths of the selected developmental stages are positively correlated with air temperature and negatively correlated with the sum and number of days with precipitation in these stages. A 1°C increase in air temperature resulted in a shortening of the shooting – heading and heading – full maturity periods by 2.5 and 2.8 days respectively. An increase of 100 mm of precipitation in the periods sowing – full maturity and heading – full maturity resulted in an increase of these periods by 5 and 10 days. Increasing the number of days with precipitation by 10 days in the sowing – full maturity and heading – vax maturity stages resulted in extending these stages by 4.1 to 4.4 and 7 to 7.5 days for the A1 and A2 cropping technologies, respectively.

The motion of viscous compressible magnetohydrodynamics (MHD) is considered in a domain bounded by a free boundary. The motion interacts through the free surface with an electromagnetic field located in a domain that is exterior to the free surface and bounded by a given fixed surface. Some data for the electromagnetic fields are prescribed on this fixed boundary. On the free surface, jumps in magnetic and electric fields are assumed. We prove the local existence of solutions by the method of successive approximations using Sobolev–Slobodetskii spaces.