Influence of the predecessor and the seeding rates on the rape productivity

The aim of the research is to identify the optimal seeding rate of varieties and hybrids of spring rape for seeds in the conditions of Northern Kazakhstan. The subject of the research is varieties and hybrids of spring rape. On the experimental fields of the Esil state grain-feed variety seed-trial ground, located in the Republic of Kazakhstan, North Kazakhstan region, the Esil district, the village of Yavlenka, in 2019-2020, a competitive test of spring rape was carried out, represented by 5 varieties: Geros, Maikudyk, Hunter, Makhaon and 3 hybrids: Caliber, Builder, GEN0009. The study of varieties and hybrids was carried out against the background of the predecessor - pure fallow, according to several seeding rates, namely 2.0, 2.5 and 3 million viable seeds. The main counts and observations were carried out according to the approved methodology of state variety testing. The studies carried out made it possible to establish that the seed productivity of rape plants is closely related to the meteorological conditions of the growing season and the studied variants of the experiment. Having studied the seeding rates, we came to the conclusion that the highest productivity is provided by rapeseed with a seeding rate of 2.0 million and 2.5 million viable seeds, and with an increase in the seeding rate, the yield decreases. Of the samples presented, over the years of testing, the variety Maikudyk and the hybrid Bilder distinguished themselves by a constant and full-fledged harvest for a number of selected characteristics.


Introduction
To fully provide the entire region with spring rape seeds, it is necessary to search, study, and evaluate valuable varieties of both local and foreign ecotypes, resistant to the main stress factors with a stable yield over the years and minimal expenditure of material resources [1,10]. Taking into account the growing interest of commodity producers in new varieties of oilseeds, it is necessary to increase the set and testing of spring rapeseed. For this, it is necessary to intensify prospecting work to study the characteristics of varietal agricultural technology of such a valuable crop as rape [2].
With the diversification of agricultural production, the introduction of promising varieties of oilseeds, including spring rape, is cost-effective and relevant. One of the main factors in increasing the gross yield of spring rape is the selection of varieties. About 85% of rape are produced by the spring forms of this crop [3,6].
Over the past few decades, many positions in the technology of cultivation of spring rape have changed: every year there are innovations in the technology of sowing and caring for crops, the composition of pesticides has changed for the protection of crops, and the varietal composition has also  [8].
The aim of the research is to study the influence of the predecessor and the seeding rate on the productivity of varieties and hybrids of spring rapeseed.

Material and methods
On the experimental fields of the Esil state grain-feed variety testing site, a competitive test of spring rape was carried out, represented by eight samples, of which 5 varieties: Geros, Maikudyk, Hunter, Makhaon and 3 hybrids: Caliber, Bilder, GEN0009. The study of varieties and hybrids was carried out against the background of two predecessors: pure fallow and spring wheat, with a seeding rate of 2.0, 2.5, and 3.0 million germinating seeds / ha [8,9].
The experiment was based on the type of seed plot for competitive variety testing, the area of the accounting plot was 25 m 2 . Quadruple repetition with 2 tiers in the experiment. The options are placed randomly [7,5]. The agrotechnics in the experiment was as follows: after harvesting the preceding crop, the soil cultivation was carried out to a depth of 20-22 cm with KPG-5 + MTZ 1221. In spring, when the soil was physically ripe, self-harrowing was carried out to a depth of 5-6 cm ZIGZAG, pre-sowing soil cultivation with simultaneous application of ammophos fertilizer at a rate of 25-30 kg / ha -SZS 2.1, aggregated by the MTZ 1221 tractor [4]. The sowing of spring rape was carried out with a Wintersteiger sower. Seeding depth -3 cm. 3-4 days after sowing -harrowing before seedling stage was carried out with a harrow -BZSS-1.0 in order to destroy weeds. Spraying of crops with the herbicide Nopasaran (0.8 l / ha) was carried out in the phase of 2-6 leaves of the crop. During the growing season, 2-fold dressing with systemic insecticides Biscay (0.3 l / ha) and Decis Profi (0.03 l / ha) was carried out to combat the complex of pests. Harvesting is carried out using Wintersteiger selection harvester. At the end of the harvesting, the necessary laboratory work was carried out. The main surveys and observations were carried out according to the approved methodology of state variety testing. The structure of the yield was determined by sheaves taken from plots with a size of 0.25 m2 (4 on each plot) for all options [8].

Research results
The researchers have found that the yield of spring rapeseed had a trustworthy average relationship with the number of fruits per plant, the number of seeds in the pod (fruit). As a result of observations, it was found that the maximum number of pods per plant on average for 2 years was formed by hybrid Bilder and variety Maikudyk -38.3 pcs / plant, which exceeded -1.8 pcs / plant. in terms of pure fallow. The maximum number of seeds in a pod was formed by the Maikudyk variety (17.6 pcs.). Having the highest height -110.1 cm, it showed the highest yield according to the predecessor, pure fallow (3.52 t / ha) ( Table 1). In terms of seeding rates, the varieties Yubileiny, Maykudyk and the Bilder hybrid showed good results. With seeding rates of 2-2.5 million viable seeds, they are leaders according to most indicators. The greatest number of branches per plant was formed by varieties and hybrids with a seeding rate of 2 million viable seeds. On average this indicator was 3.8 pcs / plant. 38.3 pcs / plant of pods were formed by varieties Yubileiny, Maikudyk and hybrid Bilder with a seeding rate of 2 million viable seeds. The largest number of seeds was observed in the varieties Yubileiny (24.9 pcs / fruit) and Maikudyk (17.6 pcs / fruit) ( Table 2). Thus, according to the studied economically useful traits, the leading varieties are Maikudyk, Jubilee, and the Bilder hybrid. The yield of varieties and hybrids of spring rape was formed mainly because of quantitative traitsthe number of fruits per plant and the number of seeds per fruit. According to the results of the experiments, the yield of seeds varied significantly from year to year, depending on the meteorological conditions, the variety or hybrid. In terms of seed productivity, the most adapted were the Maikudyk variety and the Bilder hybrid (Table 3).
Bearing in mind the experience with predecessors, the highest average yield was shown by the Maikudyk variety -3.52 t / ha. It is more than the control by 0.43 t / ha for the predecessor -pure fallow (on average for 2019-2020). There is also a need to clarify the seeding rate of the tested varieties for the production conditions. The results of the research of the optimal seeding rate showed that the highest productivity is provided by rape with a seeding rate of 2.0 million viable seeds. With an increase in the rate, the yield decreases, in particular the Maikudyk variety has a yield of 4.28 t / ha at a seeding rate of 2 million viable seeds. With an increase in its seeding rate the yield decreased to 3.20 t / ha at a seeding rate of 3 million viable seeds (table 4). Optimization of plant density is one of the most important conditions for the formation of highly productive crops of spring rape, and the planning of plant density per hectare of crops for harvesting is achieved by setting the correct seeding rate [6].