THE SOYBEAN YIELD FORMATION IN THE PEDOCLIMATIC CONDITIONS FROM THE HILLY AREA OF THE TRANSYLVANIA PLAIN

. Soybean yield is determined by the interaction between genetic potential and environmental factors from the specific area, maturity group of the cultivar, plants height, disease and pest tolerance, culture technology, the type of soil its pH and fertility, etc. From the most important elements that compete for the formation of the crop we mention, plants height, the number of pods per plant, the number of grains in the pod, weight of grains per plant and the mass of a thousand kernels weights (TKW). Experience established at ARDS Turda, during 2020-2022, had as its main objective the study of the influence of technological factors (tillage systems) and pedoclimatic effects on some morpho-productive characters in soybeans. Climatic conditions during the experiment period, especially in the summer, they had a significant influence (positive or negative) on the studied elements. Between the two tillage systems (plow CS and chisel MTC) no significant differences were recorded regarding for most of the analyzed elements, except for the number of grains/plant (CS 87.9 și MTC 95.8).


INTRODUCTION
Worldwide, soybeans is cultivated on extensive areas, being recognized and appreciated due to its various uses: in human food, animal feed, industry, to obtain ecological fuel but also as a plant that improves the physical properties of the soil by improving the soil in nitrogen (Jayachandran and Xu, 2015; Hemingway et al., 2015; Voora et al., 2020). One of the very important technological links in the success of the crop is the fight against weeds (Nagy et al., 1988). It is known that soybeans in the first weeks after emergence have a slow growth rate and is vulnerable to weeding (Berca, 2004), the same situation also occurs at maturity when it loses its foliage (Chețan, 2015).
As an agrotechnical point, soybean contributes to increasing soil fertility and it is an economic crop, using 35-50% nitrogen from the soil solution (the nitric, ammoniacal and amide form) and 50-65% nitrogen from symbiosis with bacteria Bradyrhizobium japonicum which are found in soybean root nodules (Veteri and Schmidt 1987;Mullen et al., 1988; https://www.agro.basf.ro). Nitrogen-fixing bacteria thrive on well-supplied soils with phosphorus, potassium, sulphur, calcium, molybdenum, magnesium, cobalt, in optimal humidity and temperature conditions (https://agrobiznes.ro). The specialized literature mentions that leguminous plants, depending on the crop conditions, species, cultivar and growing season, can fix between 100-300 kg N/ha (https://www.legumehub.eu/ro). Some authors recommend concurrently with weed control treatments, diseases and crop pests also the application of foliar fertilizers N:P:K type in equal proportion or in favor of phosphorus (Mandal et al., 2009;Lana et al., 2003; https://agrobiznes.ro).
At Turda, the soils are in the area of the unit, characterized as fertile soils and the presence of bacteria of Rhizobium have somewhat limited the application of mineral nitrogen to soybeans (Chețan, 2019). Soybean is less demanding than the preceding plant, but prefers straw cereals, maize, sugar beet and potato. Other leguminous plants are not indicated as precursors (Ion, 2010) but also sunflowers and rapeseed, because of common diseases (Samuil, 2007) such as white rot (Sclerotinia sclerotiorum). Supports monoculture for 2-3 years, but in this case outbreaks of diseases increase, specific pests multiply and the degree of weeding of the land increases (Li-ming et al., 2016; Chamberlain et al., 2021; https://www.cartiagricole.ro/cultura-soiei).
"In the current conditions, when the lack of protein in the food of the population and in the rations of animals is acutely felt, when there is a reduction in the possibilities to buy mineral fertilizers, of pesticides and other preparations, growing importance belongs to leguminous crops, including soybean" (https://www.sanatatea plantelor.ro).
The yield is conditioned to the greatest extent by the pedoclimatic conditions in the experimental area, the tillage system and the applied technological elements (Chețan, 2020;Doorenbos and Kassam, 1979;Chilambwe et al., 2022;Zhang et al., 2022;Chețan et al., 2022). Numerous other studies, conducted worldwide, specifies that the yield of this crop decreases considerably with the deviation from the optimum (positive or negative) of temperatures and precipitation, in different phases of vegetation, especially at flowering and beans formation (Pedersen et al., 2004;Tacarindua et al., 2013;Kim et al., 2020). The prolonged drought of this period correlated with high temperatures, considerably reduces production (Setiyono et al., 2007;Novikova et al., 2018;Hodges and French, 1985). As it appears from the research, the biggest impact in the success of the culture is attributed to the crop conditions, and here we primarily refer to the action of the main abiotic factors of temperature and precipitation. In this work, the results of the research on the influence of climatic conditions and the type of tillage are presented, on the main elements of soybean production in the hilly area of Transylvania.

MATERIAL AND METHODS
At Agricultural Research and development Station (A.R.D.S.) Turda, an experimental field was established with two tillage systems, which is included in a three-year rotation: winter wheat -corn -soybean. The experiment was located on a vertic clay illuvial chernozem soil type (SRTS, 2012) with neutral pH, good supply of phosphorus and potassium, an average content in humus and total nitrogen and clay content over 41% (OSPA Cluj). The experience is organized according to the method of subdivided plots. The surface of the experimental plot is 48 m 2 . The biological material was the soybean variety "Felix" created at ARDS Turda.
Experimental factors: -factor A, the climatic conditions of the year of experimentation: a1 2020, a2 2021, a3 2022; -factor B, the tillage system: b1 conventional, plow(CS), b2 unconventional, chisel (MTC). Agricultural lands in the unit area are infected annually with different species of weeds (Șimon et al., 2020), the highest frequency belongs to annual dicotyledonous weeds (Chețan et al., 2016(Chețan et al., , 2022. Weed control treatment was carried out in stages: in preemergence with 0,35 l/ha product based on Metribuzin 600 g/l + 1,4 l/ha based on Dimetenamid-P; in post-emergence, when the soybean plants had formed 3-4 trifoliate leaves, with 1,9 l/ha product based on Bentazon 480 g/l and Imazamox 22,4 g/l + after 3 days 1,0 l/ha product based on Propaquizafop 100 g/l. Soybean sowing + fertilization (Amonium nitrate 100 kg ha -1 ) was performed in the first decade of April in each year of experimentation, with the seeder Directa 400, population densities 650.000 plants ha -1 and row spacing of 18 cm. In the years 2021 and 2022, against the backdrop of high temperatures correlated with low rainfall in June, the red spider attack was reported (Tetranychus urtice Koch) at the beginning of July, being necessary the treatment with 0,5 l/ha acaricide based on Fenpiroximat 50 g/l.
Before soybean harvesting, 20 plants were extracted from each experimental variant for determining productivity elements (plant height, number of pods, grains/plant, weight of grains/plant, TKW). The interpretation of the experimental results was carried out by the variance analysis method (Polifact, 2015) and establishing LSD (5%, 1%, 0.1%). To analyze the relationship between the studied characters, we used the calculation of linear regressions expressed by the degree equation I y = a+bx. The correlation coefficients were established using the correlation coefficient "r" (Ceapoiu, 1968). The climatic conditions for the period 2020-2022 are presented in Table 1 (source Turda Meteorological Station: long. 23°47, lat. 46°35', alt. 427 m).

RESULTS AND DISCUSSION
If we analyze climatic the April September period of the years of experimentation (Table 1) and we refer to the multi-year average of the last 65 years (1957-present) it is noticed as well that the weather is warming up in Turda. Compared to the multi-year temperature average (16.3 o C) and the amount of precipitation (376.1 mm) close values were recorded only in 2021 (16.5 o C and379.3 mm) the deviation being of 0.2 o C and 3.2 mm. In the two years, 2020 and 2022, the deviation from multi-year was of 0.8 o C and between 30.8-54.9 mm. Requirements, water consumption of soybeans, it is higher starting from the early flowering phenophase (mid June) and until the grains are full (mid-August), the lack of precipitation during this period inevitably leads to a yield decrease (Ashley and Ethridge, 1978; https://www.agro.basf.ro). Specific to June of the year 2021, is the alarming increase in temperature compared to the multi-year monthly average, the deviation being of 3.1ºC and in the other two experimental years, significant deviations from the multi-year monthly average were recorded in July of 2.9ºC in 2021 and by 3.3ºC in 2022 (Șimon, 2022). Plant height is a particularly important character, which positively or negatively influences the arrangement of the nodes and implicitly the number of pods per stem. In the first two experimental years, were more favorable climatic conditions for soybean crop and the rains in June and July led to an increase in plant height (91.3 cm respectively 96.3 cm) if we refer to the control variant of 80.8 cm (the average of the experimental years). The drought and heat of the summer in 2022 has distinctly negatively influenced the development of crop, the average height of the plants being only 54.8 cm. The difference in height between plants grown in CS and MTC it's just by 1.7 cm and has no statistical significance. And from the interaction of the factors year x tillage system the positive influence can be observed (significantly, distinctly significant) of the two years (2020, 2021) and the negative influence of the year 2022 (distinctly significant) regardless of the tillage system (Table 2)  Compared to the control variant (51.7 pods/plant), the number of pods formed in the year 2020 (52.1 pods) it result not to have been significantly influenced by climatic conditions and tillage system (CS 51.5 pods and MTC 51.9 pods) but this particularly important element was influenced very significantly positive of 2021 conditions and both tillage systems. Both in the CS and MTC system in the year 2022, against the background of the high thermal regime and poor rainfall, had a very significant negative influence on pod formation, their number being very reduced (Table 3).   It should be mentioned that in 2022 there were five scorching heat days in June (Tmax ≥32ºC) and a day with hot temperatures (Tmax ≥35ºC) and in July there were 16 scorching heat days and six days with hot temperatures. The year 2021 featured 11 scorching heat days in July (Șimon, 2022). The average grain weight/plant was distinctly significantly negatively influenced by the climatic conditions of the year 2022, and less than the tillage system, as are from the data presented in Table 5.  The thousand kernel weight (TKW) may have different values from one year to another, depending on the thermal and water regime recorded during the vegetation period of the crop. So compared to the average of the years (control 136.7 g), TKW is significantly negatively influenced by the conditions in 2022 (121.7 g). In 2021 it seems that soybeans benefited from temperatures and precipitation that favored better plant development and obviously also the increase in the values of some production elements, as is the case TKW (149.9 g), situation presented in Table 6.  For both systems we performed the analysis of the correlations between the quantitative components of the production. Thus, from figure 1 results that there is a very significant positive relationship between the number of grains/plant and their weight, with the correlation coefficients range of 0.95 and 0.92. Also, from the same figure it results that the points are quite close to the regression lines, a fact that suggests that the two tillage systems do not have a considerable impact on the two analyzed components.
A very significant direct relationship (r = 0.699 in MTC and 0.753 in CS) there is also between grain weight/plant and the thousand kernel weight (TKW), correlation coefficients having high and highly significant values (figure 2). The regression lines for the two systems are almost parallel and quite close, a fact that suggests that the relationship between the two components is not affected by the tillage system.
Between plant height and number of pods/plant, there is a positive, highly significant relationship, aspect that is reproduced in figure 3. It can also be observed as well that in the case of these two components, tillage systems do not have a significant impact on this relationship, the regression lines being very close to each other and almost overlapping. However, this relationship must be viewed with some sensitivity because too large plant height can negatively affect resistance to falling. For the plants it would be normal to have a short waist and short internode length and a high number of pods per node.
And regarding the relationship between the number of pods/plant and the number of grains there is a very close relationship, the correlation coefficients "r" being of 0.938 in MTC respectively 0.940 in CS (Figure 4). In the relationship between the number of pods and the number of grains, the difference between the conventional . They state that research on production elements is especially important in the field of plant breeding, by knowing the close links between some production characters, more efficient cultivation can be obtained and we can also say that the selection carried out for a certain property can simultaneously lead to the improvement of another property of interest. Certain unfavorable correlations could also be corrected to some extent with the help of technology elements (the indirect relationship between protein and production etc.). Pods umber.
Grains number