Studying of a nitrogen-fixing and productional ability of different varieties of soya bean

Soya is the main protein and oil-bearing crop of modern world agriculture which ranks second to none according to the contents of biologically valuable protein and oil in seeds.

In 2012 the cultivated area of soya in the world was 106.6 million hectares, in Russia-1487 thousand hectares, in Central district – 220 thousand hectares (Belgorod-92, Orel – 25 thousand hectares.).

Soya cultivation development program accepted in Russia plans to increase cultivated areas by 2017 to 2.7 million hectares, including in Central district (Belgorod, Voronezh, Orel) to 500 thousand hectares [1].

Soya expansion to new, more northern regions of cultivation (width 48-520) became possible in connection with creation and introduction in production of early ripening varieties of northern ecotype with growing season length about 100 - 115 days, such as Lantsetnaya, Svapa and others, steadily ripping in the conditions of the Orel region.

However the climate change tendency towards warming is noted in the last decades. According to forecasts of climatologists, ground temperature can increase on 1.4-5.80 C by the end of 21 centuries that will lead to lengthening of the crop season for 1.5 months, and the annual sum of effective temperatures will increase on 600-6500 C. (2) Such climate changes will promote both to soya expansion to northern regions of our country and to cultivation in our region of more late-maturing varieties.

In this regard the purpose of the real work was studying the influence of an inoculation and mineral nitrogen application on efficiency of new soya varieties Mezenka and Zusha created in the All-Russia Scientific Research Institute of grain legumes and cereal crops.

METHODS OF RESEARCH

Researches were conducted in 2011-2013 on a skilled site of laboratory of genetics and biotechnology Federal State Budgetary Scientific Institution the All-Russia Scientific Research Institute of grain legumes and cereal crops.

The responsiveness on a nitraginization of two new soy varieties Zusha and Mezenka selected in the All-Russia Scientific Research Institute of grain legumes and cereal crops was studied in an experiment field. Lantsetnaya variety was used as control. The following variants were put on each variety: control without inoculation, variant with application of mineral nitrogen in a dose of 60 kg of active ingredient on hectare and variants with a strain inoculation 634.

Frequency of experiments is the quadruple. The area of test plots – 10 m2. Seeding – wide-row, row-width spacing – 45 sm. Seeding rate – 600 thousand the seeds viable on 1 hectare. Seeding – by the seeder SKS-6-10. Nitrogin for an inoculation was received from all-Russian Scientific Research Institute of agricultural microbiology (Pushkin St. Petersburg). Formation of the symbiotic device was estimated on activity of nitrogenase enzyme by method of an acetylene reduction and by quantity and mass of root galls on the plants. The indicators of photosynthetic plants activity were also defined. The enumeration of seed harvest was from every plot, by the continuous threshing of the Sampo-130 combines.

Seeding in all years was carried out in the second decade of May. In 2011 the harvesting of Lantsetnay was carried out on September 7, Zusha and Mezenka-on September 20. In 2012 Lantsetnaya was harvested on September 12, Zusha and Mezenka – on September 17. In 2013 in connection with heavy rain falls in September the harvesting of all varieties was carried out on October 4.

RESULTS OF RESEARCH

Climatic conditions of the crop season in 2011 were favorable for soya development and were characterized by a large amount of rainfall (373mm or 130% of long-time average annual) and by rather high temperature (the excess of long-time average annual on 1.3-4C0) during the all crop season. It is possible to admit the distribution of rainfall on the crop season was optimum as their main quantity dropped out during formation of reproductive organs (from third decade of June to the second decade of August) which is the main maximum of soy’s water consumption. These conditions allowed receiving the heaviest yield for years of carrying out the experiments with the studied varieties.

Climatic conditions of the crop seasons in 2012 and 2013 were similar and were less favorable for soya development in comparison with 2011. Temperature range was characterized by rather high temperature (the excess of long-time average annual on months on 0,9-3,3 °C) during all crop season that it is possible to characterize as near optimal for soya development. The precipitation for the crop season was 276 mm in 2012 and 216 mm in 2013. Thus the soil moisture deficit was observed during formation of reproductive organs that led to decrease in level of a crop.

Table1 - Meteo conditions of the crop seasons in 2011-2013

indicators		May	June	July	August	September
Long-time average annual precipitation		53	61	80	67	57
Long-time average annual temperature, oС		13,0	16,9	18,5	17,1	11,7
Precipitation, mm	2011г	27,2	64,5	143,7	126,8	40,1
	2012	15,9	93,6	59,5	70,5	27,3
	2013	64,3	68,5	49,5	33,2	108,5
Average temperature, oС	2011г.	15,6	19,4	22,1	18,3	12,6
	2012	16,8	17,7	21,0	18,8	13,9
	2013	18,0	19,8	18,7	18,9	10,6

Rather high level of nitrogenase activity in all variants was revealed at an assessment of parameters of a symbiotic nitrogen fixation. The existence of a large number of knobs and high level of nitrogenase activity on the control variant speaks for existence in the soil of a test plot of numerous spontaneous populations a soya rhizobium that complicates an assessment of a real contribution of a symbiotic nitrogen fixation in the crop formation. The increase of nitrogenase activity level at the tested varieties on the early development phases was approximately equally and reached a maximum to a bud-formation period. Decrease in level of nitrogenase activity was noted in a phase of filling beans and stopped at Lantsetnaya variety by the beginning of August. The longer period of nitrogenase activity (till 3rd decade of August) and higher level of a knob formation on late phases of development was noted at late-season varieties Zusha and Mezenka. The reduction effect of a nitrogenase activity at mineral nitrogen application was seen on earlier phases of development and leveled on later phases. According to the variety factor the higher level of nitrogenase activity is noted on Zusha and Mezenka varieties at an inoculation by a strain 634 (table 2).

Table 2 - Influence of an inoculation on indicators of symbiotic activity of soya varieties (knobs quantity, nitrogenase activity, piece/plant, mkgN/plant/hr); (beans formation phase, 2011-2013)

Variants	Control		N 60		Strain 634
	piece/plant	mkgN/plant/hr	piece/plant	mkgN/plant/hr	piece/plant	mkgN/plant/hr
Lantsetnay	30	55,8	19	33,5	23	50,6
Zusha	36	55,0	29	47,0	41	78,3
Mezenka	25	35,3	19	23,6	45	68,5
Average by variant	30,0	48,7	22,3	34,7	36,3	65,8

As many researchers note, the essential value in increase of soya efficiency has accumulation of green and dry material of plants. Thus the formation of a sheet surface depends on district width: the southern soya is growing up, the higher it is and vice versa, and net productivity of photosynthesis at the same varieties is more in northern areas where formation of the leaves area goes more weakly [3]. Thus the area of a sheet surface is directly connected with efficiency of crops. [4,5]. With reduction or increase in number of leaves in a direct proportion the number of beans, and, therefore, a crop of seeds decreases or increases [6]. However such tendency is traced generally at low values of a sheet surface. So in experiments of All-union scientific research institute of soya [7,8] at soya productivity 612 and 14-16 c/hectare the maximum area of a leaf area was correspondingly 10-17 and 1120 thousand sq.m/hectare. In more southern latitudes (Krasnodar Region), even at a moderate amount of precipitation during growth of soya vegetative organs , only the shortseason varieties by the time of achievement of the greatest size had no superfluous index of the leaves area and varied depending on a variety from 3.75 sq.m/m to 7.46 m2/m [9]. At such sizes of the leaf apparatus the distinct tendency especially of lower efficiency of photosynthesis is found, than the size of an index of the leaves area of soya crops was bigger that as a result leads to formation of an identical crop of the general biomass. The similar tendency is traced in our experiments in comparison to photosynthetic indicators during the years which are differing according to moisture providing (Table 3).

Table 3 - The influence of an inoculation for indicators of photosynthetic activity of soya varieties of soya (maximum leaves area, photosynthetic potential, net photosynthesis productivity)

Variants	2011			2012
	S of leaves	photosynthetic potential	net photosynthesis productivity	S of leaves	photosynthetic potential	net photosynthesis productivity
	one thousand sq.m / hectare	one thousand sq.m days/hectare	hectare / sq.m per day	one thousand sq.m/hectare	one thousand sq.m days/hectare	hectare/ sq.m per day
Lantsetnaya	56,2	2,86	2,54	38,8	1,93	2,78
Zusha	57,2	2,91	2,88	41,5	2,17	3,23
Mezenka	58,2	2,98	3,64	44,8	2,34	3,04
Average by a year	57,2	2,92	3,02	41,7	2,15	3,02

So in 2011, more favorable on moisture security, the area of a soya leaf surface in a phase of seeds filling reached 57.2 thousand sq.m/hectare, and in 2012 in connection with a lack of moisture was 1.3 times less and was 41.7 thousand sq.m/hectare.

In crop estimating for years of taking the experiments it should be noted strong variability depending on weather conditions, and first of all from quantity and nature of distribution of rainfall during the crop season, and also from the level of provision with nitrogen. Optimum conditions for soya are created at 300 mm of rainfall and more for the crop season [10]. The mean annual precipitation for the most probable soya crop season makes about 290 mm for the Orel region. The conditions of 2011 corresponded to optimum level of precipitation amount, and this allowed to creation of the greatest crop for all years of researches.

The estimated varieties in our experiments according to the international classification belong to the short season group 000, but according to the classification of All-Union Research Institute of Plant Breeding they are subdivided into two groups. Lantsetnaya, ripping in 98-109 days belongs to the short season group, and Zusha and Mezenka ripping in 110-120 days belong to the middle-early group. Plants potential efficiency to a great extent is defined by duration of production processes therefore under optimum conditions of soy variety cultivation usually that is more yielding, than they later ripening. The varieties of the second group are distinguished by higher level of productivity and higher nitrogen-fixing potential that naturally raised their resource-and energy saving role in an agrocenosis. Inoculation, and application of mineral nitrogen had positive influence on formation of seeds crop, and the bigger effect from an inoculation was observed with optimum moisture providing (tab. 4).

On the average of three years the efficiency of an inoculation exceeded the mineral nitrogen application in a dose of 60 kg for hectare.

Table 4 - Soya varieties response on an inoculation, c/hectare

variants                                    1	Lantsetnaya	Zusha	Mezenka	On the average
2011
Check	26,1	32,0	37,4	31,8
N 60	26,5	31,9	37,9	32,1
Strain634	28,4	34,2	39,9	34,2
Average on a variety factor	26,9	32,7	38,1
HCP05 on a strain factor variety	2,2 1,6
2012
Check	23,8	23,7	24,9	24,1
N 60	24,1	24,0	25,7	24,6
Strain634	24,0	24,9	27,5	25,5
Average on a variety factor	24,0	24,2	26,0
HCP05 on a strain factor variety	2,4 1,8
2013
Check	26,4	26,0	27,4	26,6
N 60	27,2	25,2	29,8	27,4
Strain634	26,2	26,2	27,4	26,6
Average on a variety factor	26,6	25,8	27,9
HCP05 on a strain factor variety	F факт. < F табл. 1,1

However adaptation of the tested soya varieties to concrete soil climatic conditions significantly stands in contrast. A.I. Kuptsov (11) noted that because of the adaptability to conditions of monsoonal climate a little possibly wide cultivation of soya on grain in the European part of our country. In the conditions of our region the main limiting factor of soya growth productivity are insufficient resources of moisture, especially during the reproductive plant growth (July-August). Thus the distribution of rainfall during the crop season plays an important role. Short-season varieties which use spring soil reserves of moisture and rainfall of May-June more rationally have advantage on formation of a crop with excess of rainfall in the first half of summer, and less suffering from a July-August drought and a heat. The later-season varieties have advantage in case of enough rains in the second half of summer. So, in 2011 more favorable providing in moisture, later-season variety Mezenka had an output yield of 38,1 c/hectare and exceeded an short-season variety Lantsetnaya on 11.2 c/hectare or for 41,6% (Tab. 5). In 2012-2013 having lack of moisture in the second half of summer the realized yield of variety was the higher, the shorter-season variety was. The short-season variety Lantsetnaya had almost the same yield, as well as later-season varieties in 2012 and 2013.

Table 5 - Crop yield of soya variety, c/hectare

Variants	Lantsetnaya	Zusha	Mezenka
2011 y	26,9	32,7	38,1
2012	24,0	24,2	26,0
2013	26,6	25,8	27,9
Average for 3 years	25,8	27,6	30,7

CONCLUSIONS

It is established that the soya seeds inoculation by nitragin on the basis of a strain 634 is more effective, than application of mineral nitrogen in a dose of 60 kg on hectare on the dark gray forest soil in the conditions of the Orel region. Zusha and Mezenka middle-early varieties exceed Lantsetnaya variety in productivity level and realize productive potential more effectively at enough rainfall in the second half of the crop season. For the stabilization of soya productivity level it is necessary to orientate for cultivation of the soy varieties differing on ripeness.