Effects of combined nutrient supply treatments on some physiological parameters of autumn wheat

The Fleischmann Rudolf Research Institute in Kompolt is not only famous for plant breeding but the institute also surveys the effects of different nutrient supply methods since 1918. In 2017, we joined this research supported by EFOP 3.6.1 project. Our aim was to investigate photochemical processes – which is one of the most determinant in case of yield – of crops by in vivo field measurements. We measured the chlorophyll content of leaves using Minolta SPAD 502. We used miniPAM fluorometer to determine actual photochemical efficiency and non-photochemical quenching of PSII during natural light conditions and also to evaluate the pigment (chlorophylls and carotenoids) and water content of leaves we applied field spectrophotometer (ASD FieldSpecPro 3). We utilized these methods by various treatments (1. treatment with soil bacteria + head and base fertilizer; 2. treated by only head fertilizer; 3. treated by only base-fertilizer) in field experiment of autumn wheat (4.1–2.43–1.19 ha) in June, 2017. The difference between treatments was clearly detectable. In the case of the first treatment, physiological processes were more intense and the ripening occurred earlier. The obtained yield was the highest in the case of the area treated by soil bacterial. Based on the results, the first treatment can be recommended in practice.


Introduction
In the Fleischmann Rudolf Research Institute investigation the effects of various nutrition supply systems has been outmost importance for nearly 100 years. In 2017 we joined these experiments in order to monitor the photochemical processes of plants by in vivo field measurements, which can influence the quantity and quality of yield. Among our arable crops, autumn wheat has paramount importance for both food and feed purposes. Due to the excellent ecological conditions of the Carpathian Basin, Hungary is a major wheat-making country. According to FAO data (Net1), the world's wheat production area exceeds 220 million hectares, from it, Hungary represents approximately 0.5%. All harvested crops have grown since 1990; in 2016 it was 740 million tons. In Hungary, however, it shows a downward trend. In 1990 it still exceeded 6 million t, but in 2016 it did not reach already 4.8 million t. The CSO (Net2) also reported lower values, but in a smaller area (1.044 thousand hectares) a larger quantity (5603 thousand tons) was aggregated. However, the domestic average yield is still increasing. In 2014, 4.7 t ha -1 and in 2016 5.37 t ha -1 wheat were recorded in register of the CSO. This is most likely due to technological development as well as the increasing amount of fertilizer used. The fertilizer per hectare of agricultural land in 2000 was 61 kg; by 2016 it rose to 103 kg. Monoculture cultivation and increasing amounts of fertilizer use are increasingly burdening the environment. However, farmers are forced to increase agricultural production during climate change conditions and demographic explosion of developing countries. The goal is to produce a larger quantity in a smaller area. An important element of sustainable agriculture is the preservation of soil fertility. Crop security is a key issue for achieving successful agriculture in the long term. To achieve this, the use of soil bacteria will help. Several similar products have appeared on the market over the last years.

Properties of the experimental area
The experiment was carried out at the Fleischmann Rudolf Research Institute in Kompolt, which is located in the southern part of the southern mountain range of Mátra between Eger and Gyöngyös, an average of 125 meters above sea level. Its weather is extreme, especially during the summer period, with few precipitation (Holló et al., 2009ab). In 2017, the annual precipitation amounted to 529.8 mm, from which rainfall reached 418.3 mm in summer. The average number of sunny hours is 2108, and 1528 hours in the vegetation period. The average annual temperature was 10 °C, which was 10.67 °C in 2017. Over the vegetation period, in multiannual average of 17.3 °C (Herczeg, 2013), while in 2017 the average temperature was 17.05 °C according to local meteorological station data. In the area of the research institute, chernozem brown forest soil is the main soil type, the thickness of the humus layer is between 0.5 and 0.8 m (Holló and Kádár, 2003). Based on the latest soil analysis ( Table 1) the area can be characterized by poor phosphorus content, with sufficient potassium content and low humus content. The experiment was set up in 4 repetitions in the following ways: − With soil bacteria: 10 250 m 2 per repeat; − With head and basic fertilizer: 5350 m 2 per repeat; − With basic fertilizer: 2975 m 2 per repeat. The applied soil microbe product contains free-living, nitrogenbinding and phosphor-mobilization soil-dwelling bacteria (50% Pseudomonas, 25% Azotobacter és 25% Azospirillum strains) and microelements (Dilci, 2008;Szabados, 2008;Net3). The preparation does not contain any chemicals or hormones, its soil improver effect can reduce the amount of fertilizer applied (Net3). The seemingly costly treatment of bacterial preparations is suitable to reduce the adverse effects of climate change, thus achieving better quality and more crops. (Kátai, 2011;Net4).
Their use helps to create and maintain healthy, equilibrium soil life. They have already been supported by Agri-environment schemes (AES) (Net5). The beneficial effect can be solved only by living soil bacteria; therefore it is indispensable to stay alive until they are incorporated into the soil. The product has to be protected from light and high temperature until use (Net3; Net6).

Methods of measurements
We investigated some photochemical parameters using in vivo chlorophyll fluorescence induction method with miniPAM fluorometer (WALZ GmbH, Germany) under unclouded natural light conditions between 11-13 a.m. (1200-1600 µmol m -2 s -1 light intensity). We determined the actual photochemical efficiency of the PSII system (∆F/Fm'=Fm′-F/Fm′; Genty et al., 1989) and the rate of electron transport (ETR=(∆F/Fm'×PAR×0.5×0.84) and the ratio of photochemical (qP=Fm'-F/Fm'-F0) and non-photochemical processes (qN=Fm-Fm'/Fm-F0, where Fm -maximum fluorescence, F0 -basic fluorescence) (Net7; Schreiber et al., 1998). The relative chlorophyll content was measured by the Minolta SPAD 502 automatic meter. The device measures at the red light, since absorption of this is not affected by the contents of the leaf carotene (Markwell, 1995;Hawkins et al., 2009). The second leaves of the plants were measured in the upper third. For each plant 2 measurements were made to reduce measurement errors, it means 80 measurements per plot. The measurements were executed on 19 th of June in 2017, at the advanced maturation stage. We carried out spectroscopic reflectance measurements by ASD FieldSpec3 portable spectroradiometer (USA) and determined vegetation indices (NDVI, RDVI, EVI, TCARI/OSAVI, SIPI, PRI, ARI, CRI, PWI, SRWI)) from which chlorophyll, carotenoid and water content of the leaves can be calculated. The method is used to isolate the reflection properties of plants (Spinetti et al., 2009).
NDVI, RDVI vegetation indices were also determined by aerial photographs, which on a rigid, unmanned aerial vehicle (UAV) fixed 4channel multispectral camera system were made. After photogrammetric processing was the mosaic recording geometric resolution is 16 cm.
During the vegetation period, soil samples were taken, soil samples at depths 0-20 and 20-40 cm. Soil parameters were determined in the laboratory and the contents of the macro-, meso-and micro element of the soil, plant. The latter were also analyzed from stored crops.
Evaluation of differences between measured parameters in case of different treatments was performed using SPSS 20 statistical program, One-Way ANOVA method. Figure 1, at all parameters were high the deviation, this has significantly influenced the result. The control had the highest relative chlorophyll content. However, its photosynthesis activity was also outstanding. However, for the three parcels, the light intensity was not the same. When evaluating the sunscreen mechanism of the plant, higher photochemical efficiency (∆F/Fm 2 ) and lower non-photochemical photochemical extinction (qN) were measured at the control. The electron transport rate (ETR), which is calculated by the instrument based on ∆F/Fm 'and the actual light intensity significantly was different for the three parcels, the control was higher.

As shown in
It is apparent from the data in Table 2 that, like the SPAD value, the second treatment had lower the NDVI index, while the TCARI/OSAVI index was the lowest for treatment I. The photochemical reflectance index (PRI) was the highest in I. treatment. The anthocyanin (ARI) in the treatment II., while the carotinoid (CRI) reflectance index was the highest in the soil bacterial parcel. The leaf structure independent pigment index (SIPI) indicating carotenoid/chlorophyll ratio was of outstanding value in I. treatment, which also indicates the state of the plants' stress (Penũelas et al., 1995). The soil bacterial parcel had also lower water content based on the PWI index, which explains the more stressful situation than the other two treatments. The vegetation indices used for autumn wheat similarly to physiological measurements show that the two treatments improve the stress tolerance of the plants.

Figure 1. Relative chlorophyll content (SPAD value), photochemical activity (∆F/Fm'), electron transport rate (ETR), non-photochemical quenching of PSII (qN) of autumn wheat (Kompolt, 19/06/2017)
On the basis of measurements, with soil bacteria treatment is beneficial in yield, while the head fertilizer is slightly lower. The moisture content measured after harvest also confirms the soil bacteria treatment, as 1.6% less than in the other two treatments (Figure 2). The aerial photographs show the heterogeneity of plots (Figure 3). On the parcels are scattered spots visible. The soil bacterium treated seems homogeneous unlike the other two parcels.
The soil bacteria treatment presumably provided more balanced nutrient and water supply to crops, increased the parcel homogeneity, which is important for crop safety.
In table K7 soil samples were taken at 20 and 40 cm deep from the three parcels. According to our results (Table 3) In the 20 cm soil depth the soil moisture content was the lowest in the head fertilizer treatment and the dry matter content the highest. The same could be detected at a depth of 40 cm, too. The pH was the lowest in the soil bacteria treatment parcel. Based on Gold's binding a sample taken from the ground 20 cm deep showed the low value of the head fertilized treatment, but in the 40 cm depth sample it was already the same as the.
According to the results of Table 4. 20 cm in soil depth nitrate at head fertilizer treatment, nitrite, phosphorus at the control, potassium, calcium, magnesium, selenium, iron and lead in the soil bacteria treatment was the highest. At 40 cm depth nitrate, phosphorus, potassium at control, nitrite, calcium, magnesium, iron and lead at the head fertilizer treatment, selenium at soil bacteria treatment was high.
The nutrient values from stored grain yields showed high value at the control phosphorus, calcium, magnesium, iron, selenium, while in case of soil bacteria treatment they exhibited high sodium values. The head fertilizer treatment showed the values between the two treatments, alone, the potassium content was outstanding. It can be concluded that control grain extracted most nutrients from the soil ( Table 5).

Conclusions
The leaves of healthy, nearly the same size and color plants were measured, therefore measurements are not subjective. Presumably, under optimum conditions, the yield-enhancing effect is expected in the proportions of the experiment results. On aerial photographs, it is clear that parcels are heterogeneous, the most the control. Based on the results, the soil bacteria treatment can be recommended in public production, for which physiological processes were more intense, the ripening occurred sooner, and the moisture content at harvest was 1.6% lower on the soil bacteria than on the other two treatments When evaluating soil samples, the head fertilization resulted the soil to have a lower moisture content but higher dry matter content. At depths of 20 cm on the soil bacteria treatment was measured low nitrate, phosphorus, but high potassium values. In the depths of 40 cm, the result was high selenium and iron content. In the case of the grain yield, were also lower phosphorus, potassium, calcium, magnesium, iron and selenium value than on the other two treatments. The soil bacteria treatment has a beneficial effect on soil pH reduction, deeper soil level in moisture conservation and nutrient utilization.