Influence of seeding rates, sowing methods and weather conditions during vegetation on the grain yield of durra hybrids

Abstract

Since the negative upward tendency in the average annual temperature calls for revising the existing crop rotation patterns and increasing shares of drought-resistant plants, in particular sorghum, in them, there is a rising need to develop adaptive technologies for their cultivation aimed at the maximum possible fulfillment of their resource potential of performance.Thus, the relevance of investigations covering the development of adaptive technologies of sorghum cultivation is of no doubt.

The aim and tasks of the study.Our primary objective was to study the combined influence of seeding rates and sowing methods on fulfillment of the genetic potential of grain productivity of durra hybrids in the Left-Bank Forest-Steppe of Ukraine.

Materials and methods.The experiments were laid out in the experimental field of Kharkov NAU named after VV Dokuchaev by the conventional methods in 2007–2009, 2012and 2013.In this multifactorial experiment, four durra hybrids were studied. Plots I (variety, factor A): 1 – Stepnoy 8 (control); 2 – Praim; 3 –Dash E; 4 – Sprint W. Plots II (methods of sowing in broad drills, factor B): the row spacing of 45 and 70 cm. Plots III (seeding rate, factor C):120,000, 160,000, 200,000 and 240,000 seeds/ha. The experimental plot area was 20.0 m².

Results and discussion.Of the test durra hybrids, the highest grain yields in all the study years were produced by Dash E. On average, across the study years, the grain yield in this hybrid was 6.33 t/ha, exceeding those in hybrids Stepnoy 8, Praim and Sprint W by 16.4, 14.1 and 6.7% respectively.

It was found that the grain yield was greatly influenced by the seeding rate.The yield range, depending on this factor, was on average 2.02 t/ha (44.3 %) across the other test factors. Analysis of the major effect of the seeding rate showed no significant difference between the sorghum grain yields obtained at the seeding rates of 200,000 and 240,000 seeds/ha.

The effect of theseeding rate on the sorghum yield was more conspicuous with the row spacing of 45 cm.The maximum difference between the grain yields in the test variants of seeding rate with the row spacing of 45 cm was 2.3 t/ha (50%),while it was1.74 t/ha (38%) with the row spacingof 70 cm.

Of the test hybrids, on average across the study years, the maximum grain yield (6.42 t/ha) was produced by durra hybrid Dash E.It should be noted a distinct advantage of this hybrid at all the investigated seeding rates and sowing methods. In the experiments with the row spacing of 45 cm, the optimal seeding ratewas 200,000 seeds/ha. In comparison with the 160,000 seeds/ha experiments,the grain yield in this case increased by 0.5–1.5 t/ha, depending on the year.

In the test sample of hybrids,high efficiency of hybrid Sprint W was also noted.Its yield compared with the control (hybrid Stepnoy 8)was significantly greater in all the test technological variants and in all the study years.

Analysis of the investigated factors as sources of influence on the durra grain yield variability showed the dominant role of the weather conditions during the growing season, the share of which was 50 %.

Of the investigated technological factors, the seeding rate had the greatest effect on the sorghum yield variability.Its share in the total variability was 32%. Peculiarities of the hybrids under investigation accounted for about 8.5% of the grain yield variability, and only 1.3 % of the variability in this parameter was due to the sowing method influence.

Conclusions. This study accentuates that the seeding rate of durra hybrids should be chosen with due account for the weather conditions and sowing methods.

A significant advantage of sowing in broad drills with the row spacing of 45 cm and the seeding rate of 200,000 seeds/ha was noted.All the test sorghum hybrids produced the highest grain yields with this seeding rate/sowing method combination.

If durra is sown in broad drills with the row spacing of 70 cm, under unfavorable weather conditions the seeding rate can be reduced to 160,000 seeds/ha,since its further increase does not always provides a gain in the grain yield due to a drastic enhancement in competition between plants