PRELIMINARY RESEARCH ON THE PLANT STATUS OF SEVERAL WHEAT VARIETIES IN RELATION TO NITROGEN MINERAL FERTILIZATION

Abstract

The study evaluated the variation of plant height in relation to nitrogen fertilization, and took place within the Didactic and Experimental Resort (DER) of the University of Life Science "King Mihai I" from Timisoara. Six wheat varieties were studied, three with smaller height (C3 – Montecarlo, C4 – Venezio, C5 – Combin) and three with larger height (C1 – PG102, C2 – Falado, C6 – Pitar). Variable doses of nitrogen (ammonium nitrate) were applied in the range of 0-280 kg N a.s. ha-1 (a.s. – active substance). In the experimental conditions (chernozem soil) and associated with the climatic conditions, according to the genetic specificity, the wheat varieties considered in the study used the applied fertilization in a different way. The height of the plants varied between 63.67±1.45 - 73.00±1.15 cm in the C1 variety; 62.33±0.88 - 73.67±2.33 cm for the C2 variety; 56.67±1.20 - 63.67±1.45 cm for the C3 variety; 54.00±2.08 - 62.67±3.18 cm for the C4 variety; 59.00±0.58 - 70.00±1.15 cm in the C5 ace; 67.33±1.76 - 77.67±1.20 cm for the C6 variety. The data series presented a normal distribution, and a close relationship with the N doses (r=0.994 for the variety C1; r=0.980 for the variety C2; r=0.984 for the variety C3; r=0.979 for the variety C4; r=0.985 for the variety C5; r=0.983 for the C6 variety). Based on the PCA, the wheat varieties studied were positioned specifically in relation to the applied fertilization; PC1 explained 92.498% of variance, and PC2 explained 4.134% of variance. The cluster analysis facilitated the clustering of variants from the perspective of wheat varieties (Coph.corr.=0.732) and from the perspective of fertilization (Coph.corr.=0.727). A ranking of the wheat varieties was obtained based on the plant height values (Ph), in response to the applied fertilization. The variation of Ph depending on the doses of N was described by polynomial equations of degree 2 and 3, under conditions of statistical safety.