The influence of weather and climatic conditions on the phenological indicators and productivity of winter wheat cultivated by direct seeding technology in the arid zone of the Stavropol Territory

Abstract

The studies were conducted in the arid zone of Stavropol region to determine the productivity of winter wheat cultivated by direct seeding technology, based on phenological observations and NDVI. The work was carried out on the basis of the agro-enterprise JSC "Agrohleboprodukt" for 2018-2020. The predecessors are sunflower, chickpeas, winter wheat varieties (Zustrich (St.), Bagheera and Bagrat). Plant samples were selected according to the generally accepted method. Satellite mapping data of vegetation cover is obtained on the basis of the service "VEGA-Science". It was found that the growth, development and productivity of winter wheat depended on the prevailing weather and climatic conditions. Studies of the dynamics of the average annual indicators showed that precipitation tended to decrease (37.6-14.4 mm), and the temperature and vegetation index NDVI-to increase (9.6-12.3 °C and 0.456-0.491, respectively). The analysis showed the absence of a reliable level of significance of the combined application of these factors for predicting the productivity of winter wheat. The terms of sowing the crop were determined by external conditions and shifted to a later period. The largest average linear deviation of the indicator was revealed in 2020 (6.4444). On average, the variation of seedlings for different varieties and predecessors was 9 % (the lowest for chickpeas – 7.5 %). Seedlings of grain crops appeared 19-20 days after sowing. The coefficient of variation showed a high heterogeneity of the phenological index for all phases, except for tillering (8.6-9.0 %). The average density of plant seedlings was 379 pcs./m2. The coefficient of variation of the indicator is uniform for all varieties and precursors (3.65 %). A decrease in plant density was observed from the germination phase to earing and for all the predecessors (the largest for the Zustrich variety – 7.3 % and 10.2 % for sunflower and chickpeas, respectively). From 2018 to 2020, the yield of winter wheat when sowing for sunflower was 301-450 t/ha, for chickpeas – 326-468 t/ha.

Productivity of Winter Wheat Cultivated by Direct Seeding: Measuring the Effect of Hydrothermal Coefficient in the Arid Zone of Central Fore-Caucasus

“…A slight increase in the average annual HTC (up to 0.43 in 2021) transforms the relationship between humidity and duration of interphase periods of plant development-the effect is observed in the sprouting phase (0.03 after sunflowers and 0.04 after chickpeas). This finding correlates with the results of the earlier studies of Dridiger and Gadzhiumarov [62] and Pismennaya et al [20], who demonstrated that in extremely arid areas, precipitation in winter and during the growing season increases winter wheat yields significantly, especially after sunflower.…”

“…Supporting the findings of Szczepanek et al [28] and Hou et al [93], who revealed a significant correlation of the grain yield with the amount of precipitation in tillering, the study concludes that drought affects the duration of interphase periods of winter wheat development mainly in the phases of spring tillering and earing (in 2019, HTC = 0.85) (Table 8). Earlier, Pismennaya et al [20] found that at the tillering stage, the coefficient of variation showed no substantial heterogeneity of the phenological index for winter wheat. Conversely, this study demonstrates that the proximity of D index in different phases of plant development indicates homogeneity of phenotypic processes.…”

“…This measure has been widely applied as a principal quantitative indicator of the ratio of humidity and temperature in studying the relationships between the amount of precipitation in the time period, when average day temperature exceeds +10 • C, and the sum of temperature, in degrees in the same period [18,79]. Volkov et al [80] and Pismennaya et al [20] specifically demonstrated the employability of the coefficient in studying the influence of annual precipitation on the stability of winter wheat yields across arid and semiarid zones in Caucasus. HTC is calculated as follows (1):…”

“…In arid environments, where the yields are particularly vulnerable to the slightest changes in climatic conditions, low humidity associated with high temperature deteriorates the productivity of winter wheat crops radically [7][8][9][10][11]. The degree of plant tolerance to drought varies during ontogenesis [12][13][14], but both varietal differences and temperature parameters equally affect the duration of the vegetation period [15][16][17][18][19][20]. Therefore, yield is determined not only by genes of quantitative traits, but also by the emergence of the "genotype-environment" system, which puts forward ontogenetic, population, and phytocenotic properties of high levels of organization [14,21].…”

“…Some authors have tempted to investigate the perspectives of using no-till technologies and direct seeding practices to moderate the effects of climate-related parameters on yields [16,[57][58][59][60][61]. Dridiger and Gadzhiumarov [62], Pismennaya et al [20], Goryanin and Shcherbinina [63], Litvinova et al [64], and Boktaev et al [65] are among those few scholars who have tested the possibility and effectiveness of applying the direct seeding method in extremely arid zones in Russia's South and the Volga region, as well as in the countries of Central and East Asia. Although Geleta et al [14] acknowledged the seeding rate to be a critical factor in increasing grain yields, the general finding for extreme arid zones is that the decrease in the seeding rate is permissible, while the productivity of winter wheat is mainly determined by the volume of productive moisture in spring [64,[66][67][68].…”