Monika Marković

Evaluation of Different Soil Water Potential by Field Capacity Threshold in Combination with a Triggered Irrigation Module

Irrigation efficiency improvement requires optimization of its parameters like irrigation scheduling, threshold and amount of water usage. If these parameters are not satisfactorily optimized, negative consequences for the plantsoil system can occur with decreased yield and hence economic viability of the agricultural production. Numerical modelling represents an efficient, i.e. simple and fast method for optimizing and testing different irrigation scenarios. In this study HYDRUS-1D model assuming single- and dual- porosity systems was used to evaluate a triggered irrigation module for irrigation scheduling in maize/soybean cropping trials. Irrigation treatment consisted of two irrigation regimes (A2 = 60–100% field capacity (FC) and A3 = 80–100% FC) and control plot (A1) without irrigation. The model showed a very good fit to the measured data with satisfactory model efficiency values of 0.77, 0.69, and 0.93 (single-porosity model) and 0.84, 0.67, and 0.92 (dual-porosity model) for A1, A2, and A3 plots, respectively. The single-porosity model gave a slightly better fit in the irrigated plots while the dual-porosity model gave better performance in the control plot. This inconsistency between the two approaches is due to the manual irrigation triggering and uncertainty in field data timing collection. Using the triggered irrigation module provided more irrigation events during maize and soybean crop rotation and consequently increased cumulative amounts of irrigated water. However, that increase resulted in more water available in the root zone during high evapotranspiration period. The HYDRUS code can be used to optimize irrigation threshold values further by assuming different scenarios (e.g. different irrigation threshold or scheduling) or a different crop.

Impacts of irrigation and genotype on yield, protein, starch and oil contents in grain of maize inbred lines

Four inbred lines of maize (Os 438-95 = C1, Os 30-8 = C2, Os 6 = C3 and Os 1-44 =C4) were grown for 4-year period (2006-2009) in the stationary field experiment on Osijek eutric cambisol. Impact of irrigation, nitrogen fertilization and genotype were tested. Soil moisture was maintained by two irrigation rates from 60-100% and 80-100% of the field water capacity). Two steps of N (0, 100 and 200 kg N ha-1) were applied, while P and K fertilization was equal (500 kg/ha NPK 0:30:20). Eight maize genotypes (four inbred lines and four hybrids) were grown on each basic plot of fertilization. The experiment was duplicated for maize - soybean rotation. The experiment was set by split-split plot method according to randomized block design in three replicates. The basic plot areas were 617.2 m2 (irrigation), 313.6 m2 (fertilization) and 39.2 m2 (genotype). Selection of N non-fertilized treatment and four inbred lines were made for this study with aim of testing year (A) irrigation (B) and genotype (C) effects under natural N-soil conditions. Average grain yield in level 1809 kg ha-1without N fertilization is indication of very high fertility of the soil. Differences of yield among the years were from 823 (2007) to 2450 (2006) kg ha-1. Excessive drought and high air-temperature stress is responsible for the low maize yield in 2007. Irrigation considerable affected on maize yields (4-year averages: 1500, 1809 and 2118 kg ha-1, for B1, B2 and B3, respectively). Differences of the 4-year average yields among the genotypes were from 1259 (C3) to 2765 (C1) kg ha-1. Differences of yield among the genotypes in the different years were also considerable because the lowest yield was for 71% (A1), 23% (A2), 63% (A3) and 40% (A4) lower in comparison to the highest yield. The genotype effects under different water supplies were less influencing factor because the high-yielding C1 had for 128%, 129% and 106% the higher yield compared to the low-yielding C3, for B1, B2 and B3, respectively. Differences of grain -protein, -starch and -oil among the years was from 9.61 to 11.84%, from 68.51% to 70.93% and from 3.50% to 4.17%, respectively. The C2 separated by the higher grain protein contents (10.93%) from the remaining three genotypes (average 9.96%). The genotype effects on starch and oil contents were from 69.83% (C4) to 70.58% (C1) and from 3.56% (C3) to 4.09% (C1), respectively.

Response of Maize (Zea mays L.) Grain Yield and Yield Components to Irrigation and Nitrogen Fertilization

Grain yield of maize is mostly affected by amount of available water and nitrogen and correlated to yield components. In this 2-years study the influence of different irrigation water amounts (a1=rainfed; a2=60-100% field water capacity (FWC); a3=80-100% FWC), nitrogen fertilizer levels (b1=0 kg*N*ha-1; b2=100 kg*N*ha-1; b3=200 kg*N*ha-1) and hybrids (c1=OSSK515; c2=OS5997; c3=OS5775; c4=OS5885) on grain yield and yield components was tested. Furthermore the correlation analysis as well as direct and indirect path coefficients were used to analyse the connection between yield and yield components (grain number/cob, grain weight, 1000 grain weight, cob length, cob weight) across tested treatments. The influence of all tested factors was significant (P<0.05) in both years of study. Specific study results were obtained in extremely wet year 2010 when irrigation water reduced grain yield and yield components (a1=9.9; a2=8.8; a3=7.8 t*ha-1). Opposite to year 2013 when irrigation water increased grain yield as well as yield components (a1=8.9; a2=9.7; a3=10.3 t*ha-1). Nitrogen fertilizer was significant to all tested variables in both years of the study (b1=5.7; b2=9.2; b3=11.7 t*ha-1 in 2010 and b1=6.3; b2=8.9; b3=10.6 t*ha-1 in 2013). Generally, the greatest amount of nitrogen fertilizer the larger yield or yield components are achieved. The influence of hybrid was significant for all tested variables with exemption to 1000 grain weight and grain weight/cob during growing season 2013. In both years of the study hybrid c2 OS5997 achieved the highest yield as well as yield components. Correlation analysis showed strong positive correlation between yield and cob weight (r=0.77 (2010); r=0.84 (2013)) what is confirmed with direct and indirect path analysis test.

IMPACT OF TECHNICAL SPRAYING FACTORS ON VERTICAL LIQUID DISTRIBUTION WITH AGROMEHANIKA AGP 440 AXIAL FAN SPRAYER

Original scientific paper The influence of technical spraying factors on vertical distribution of liquid and air velocity was observed and measured with vertical patternator device. In research, Lechler yellow (TR 8002C) and red (TR 8004C) nozzles are used with two different sets of fan rotor blades (two different air velocities) at 540 rpm of PTO. The research was set as controlled three factorial experiment (without the influence of weather factors) with 8 treatments in 4 repetitions, for each side of Agromehanika AGP 440 axial fan sprayer. Technical spraying factors (ISO nozzle number, settings of fan blades and spraying height) have a high significant impact (**) on the main properties of the research (vertical distribution of liquid and air velocity). By decreasing the ISO nozzle number and air velocity the increase of liquid deposit is found on vertical patternator and with the increase of measuring height a non-uniform distribution of liquid and air velocity is found. In addition, a non-uniform distribution of liquid and air velocity is established between the left and right sides of the machine. With regression analysis between the vertical distribution of liquid and air velocity on both sides of the machine, a statistically significant coherence is determined (left side of the machine: r = 0,96; p < 0,01; right side of the machine: r = 0,97; p < 0,01).

Photosynthetic performance index in early stage of growth, water use efficiency, and grain yield of winter barley cultivars

Repetitive heat and drought stress conditions have a significant impact on quantity and quality of barley (Hordeum vulgare L.) production in most regions of the world. Objective of this study was to determine the relationships between photosynthetic performance index (PIABS), water use (WU), grain yield-based water use efficiency (WUEG), and grain yield per pot (GYP) of winter barley cultivars grown in a pot trial under short-term drought stress conditions and grain yield and its stability from the multi-environmental field trials. Ten winter barley cultivars were examined in two water treatments. One treatment was well watered, while the second treatment was subjected to short-term stress caused by deficiency of water in the stages of full tillering, beginning of heading, and grain filling. PIABS was measured at full tillering stage while WU, WUEG, and GYP of barley cultivars were estimated after the whole vegetative cycle. Also, multi-environmental field trials with the same winter barley cultivars were carried out during 4 yr (2004- 2007) and 3 yr (2009-2011) with two sowing densities (300 and 450 seeds m-2) on multiple locations in the lowland part of the Republic of Croatia. ANOVA showed highly significant (P ≤ 0.001) cultivar effect for all of the examined traits in the pot trial. PIABS of cultivars in both treatments was in a negative nonsignificant correlation with grain yield and grain yield stability (ecovalence) of the same cultivars in multi-environmental field trials. Winter barley cultivars with higher WU and WUEG also had higher values of grain yield, and harvest index observed on the basis of the pot trial. WU, WUEG, and GYP of 10 barley cultivars in pot trial showed highly positive phenotypic correlation with grain yield of all eight and 10 barley cultivars in the multi-environmental field trials. These results suggests that WU and WUEG could be good indicators for preliminary selection of modern, high yielding, and stable winter barley genotypes which have better water management capabilities.