Agronomic performance of transgenic soybean cultivars in Brazilian Cerrado

ABSTRACT.

The productive capacity of soybeans is associated with the adaptation of the culture to the cultivation environment. Factors such as a high number of pods, the weight of a thousand grains, and grain number are essential factors in determining cultivars of high productive potential. The launching of new varieties associated with new technologies makes it necessary to know the performance of these varieties in different growing environments. This study aimed to analyze the agronomic performance of transgenic soybean cultivars under Cerrado conditions. The experimental design used completely randomized blocks; six of the twelve cultivars used RR₁ technology and the remaining six used RR₂BT. The cultivars were grown in five distinct locations in the southwest region of Goiás. The results demonstrated no increments in the grain yield of the RR₁ or RR₂BT technologies and the precocity of the cultivars also did not favor an increase in grain yield. The localities of Jataí and Rio Verde did not influence the cultivar cycle.

Keywords:
environments; improvement production; technology

Introduction

Soybeans are gaining in agricultural importance worldwide due to the great diversity of the use of their oilseed in addition to the continued increase of global food demand. The world soybean production for the 2016/17 crop is estimated at 324.20 million tons, of which Brazil produces approximately 32% (USDA, 2016). Brazil’s national soy production is estimated at 103 million tons for the 2016/17 harvest, of which the Cerrado region produces approximately 45% (CONAB, 2016). In addition, the region has potential for increasing the production area in the coming years.

Due to the expansion of soybean production in Goiás, there are varied environments growing soybeans especially in the Cerrado of Goiás, which makes it possible to observe the effects of these environments on grain yield. The Cerrado contains environments with variations of 500 m in altitude within radii of less than 100 km, which influences temperature and precipitation factors (Tannura, Irwin, & Good, 2008; Hassol, 2009; Mariano, 2010) and, consequently, the behavior of the cultivars (Dixon, Hollinger, Garcia, & Tirupattur, 1994).

In this regard, breeding programs are of crucial importance, since genetic gains contribute significantly to productivity and are obtained through breeding (Rocha & Vello, 1999; Machado, 2014; Xu, Hennessy, Sardana, & Moschini, 2013). To increase the yield of soybean cultivars, three main components should be selected for and evaluated to improve the agronomic performance of each cultivar (Mauad, Bertoloze, Almeida, & Abreu, 2011): the number of pods per plant, the number of grains per pod and the average weight of a thousand grains (Navarro Júnior & Costa, 2002; Guzman et al., 2007; Zhang et al., 2015).

Due to the difficulties with weeds and Lepidoptera for soy production, new herbicidetolerant soybean cultivars with different mechanisms of action and resistance to Lepidoptera have been launched (Bernardi et al., 2012; Mateus & Silva, 2013). These technologies allow the cultivars to express their full potential and give producers increased options for the management of weeds.

Due to the difficulty of recommending cultivars as a function of the genotype x environment interaction, it is necessary to perform tests on a larger number of sites (Carvalho et al., 2002; Toledo et al., 2006). In the state of Goiás, for example, there is a wide variability of growing conditions. This factor is intensified with the development of new transgenic cultivars, and the behavior of these cultivars has yet to be evaluated (Paterniani, 2001).

In Brazil, there are six transgenic events approved for soybean cultivation (Mateus & Silva, 2013). With a higher commercial representation to date, we use RR₁ soybeans which are tolerant to the glyphosate herbicide and, subsequently, RR₂BT soybeans, which have a combined resistance to insects of the order Lepidoptera and tolerance to the herbicide glyphosate. Both biotechnological events contribute to the ease of crop management and consequently a better yield.

The objective of this work was to evaluate the agronomic performance of cultivars of transgenic soybean in Cerrado conditions in the agricultural crops of 2013/14 and 2014/15.

Material and methods

The trials were conducted in the agricultural crops of 2013/14 and 2014/15 at the following five representative sites of soybean cultivation in the southwestern region of Goiás: Maurilândia (18° 02'20"S, 50° 22'25" W, altitude of 480 m), Bom Jesus de Goiás (18°01'75" S, 50°05'61'' W, altitude of 650 m), Rio Verde (17° 51'82" S, 50°55'72" W, altitude of 750 m), Jataí (18°06'44" S, 51°52'16" W, altitude of 889 m), and Montividiu (17°34'24" S, 51°17'24" W, altitude of 985 m).

The experimental design used randomized blocks with four replications. The treatments were composed of twelve cultivars of soybean representative of the cultivation in the region, as described in Table 1. The plots were composed of four rows, each row with a width of 0.50 m and a length of 5.0 m. Data was measured from the two central rows, disregarding 0.50 m from each end, totaling 4.0 m².

Table 1
Characteristics of cultivars transgenic soybeans used in the agronomic performance tests, under conditions of the Brazilian Cerrado, in crop years 2013/14 and 2014/15.

Cultivars	Technology	Cycle	Maturity Group	Company	Plants ha-1
BMX Desafio RR	RR1	Medium	7.4	BRASMAX	400,000
BMX Ponta IPRO	RR2BT	Precocious	7.0	BRASMAX	440,000
BMX Potência RR	RR1	Precocious	7.0	BRASMAX	440,000
BMX Prisma IPRO	RR2BT	Longer	7.5	BRASMAX	360,000
M 7110 IPRO	RR2BT	Medium	7.1	MONSOY	400,000
M 7739 IPRO	RR2BT	Longer	7.7	MONSOY	360,000
NA 5909 RR	RR1	Precocious	6.8	NIDERA	440,000
NA 7337 RR	RR1	Longer	7.5	NIDERA	360,000
NS 7000 IPRO	RR2BT	Precocious	7.0	NIDERA	440,000
NS 7338 IPRO	RR2BT	Medium	7.3	NIDERA	400,000
W 712 RR	RR1	Medium	7.1	WHERMAN	400,000
W 787 RR	RR1	Longer	7.6	WHERMAN	360,000

• Information provided by the companies holding the cultivars.

The sowing was performed in the rainy season on the following dates: Maurilândia (Nov. 1^st, 2013 and Nov. 5^th, 2014), Bom Jesus de Goiás (Oct. 31^st, 2013 and Nov. 4^th, 2014), Rio Verde (Nov. 15^th, 2013 and Nov. 30^th, 2014), Jataí (Oct. 22^nd, 2013 and Oct. 28^th, 2014), and Montividiu (Oct. 16^th, 2013 and Oct 22^nd, 2014). In all localities, soybean was grown in no-till systems. The desiccation of the weeds was accomplished by using 960 g of a.i. glyphosate ha^-l and 50 g of a.i. saflufenacil ha^-1 applied with a trailing sprayer with a volume of 150 L ha^-1. For fertilization recommendations, the results of soil samples were taken into account and are described for each of the locations in Table 2.

Table 2
Physical and chemical characteristics of the soils at the cultivation sites.

Lacation	Clay (%)	Silt (%)	Sand (%)	% O.M. (g dm-3)	pH (CaCl2)	Ca+2	Mg+2	Al+3	H+Al	K+	CTC (cmolc dm-3)	P	Cu (mg dm-3)	Zn (mg dm-3)	Fe (mg dm-3)
Bom Jesus de Goiás	16	8	76	14	4.2	0.23	0.10	0.53	2.92	0.05	3.31	11.11	1.44	0.17	38.90
Jataí	61	12	26	46	4.3	0.60	0.11	0.53	6.76	0.21	7.98	34.26	1.04	5.42	40.57
Maurilândia	49	8	43	37	5.0	1.66	0.43	0.05	3.72	0.19	6.00	10.64	2.27	0.88	28.74
Montividiu	53	8	38	43	5.1	2.23	0.58	0.04	3.6	0.26	6.68	23.42	1.15	5.36	27.23
Rio Verde	32	4	64	39	5.3	1.96	0.61	0.03	3.04	0.27	5.89	8.02	0.60	3.42	29.30

Rainfall data were collected at each cultivation site and are shown in Figure 1. Herbicides, insecticides and fungicides were applied to keep the plants under optimal development and growing conditions for all of the cultivation sites, thus offering the necessary conditions for the cultivars to yield as optimally as possible.

Figure
1. Mean temperature and accumulated precipitation per decant, for the duration of the study.

The following agronomic characteristics were determined: yield of grains and weight of a thousand grains, with moisture correction to 13%; number of pods per plant; and number of grains per plant. The physiological maturity (cycle) was evaluated at the reproductive stage R₇, when the pods became yellow and 50% of the leaves became yellowish (Sediyama, 2013).

The variables were submitted for a homogeneity test. When the homogeneity was verified, a joint analysis of the data was performed. After detecting significance for a given source of variation, the Scott-Knott test at 5% probability was used to compare the means of the treatments. The analyses were performed using the Sisvar program (Ferreira, 2011).

Results and discussion

The analysis of variance verified significance for genotype x year x local interaction for all variables (Table 3). This shows that the behavior of transgenic soybean cultivars was influenced by the cultivation sites in the cerrado and agricultural crops, as verified by other authors (Beavis & Keim, 1996).

Table 3
Summary of the joint variance analysis for grain yield (kg ha^-1) (Yield), weight of a thousand grains (WTG), pod number (PN), number of grains (NG), and Cycle of Cultivars of transgenic soybeans, under conditions of the Brazilian Cerrado, in the 2013/14 and 2014/15 crop years.

FV	FD	Yield	WTG	PN	NG	Cycle
Rep (Year*Location)	30	ns	ns	ns	ns	**
Genotype (G)	11	**	**	**	**	**
Year (Y)	1	**	**	ns	ns	ns
Location (L)	4	**	**	**	**	**
G*Y	11	**	**	**	**	**
G*L	44	**	**	**	**	**
Y*L	4	**	**	*	ns	**
G*Y*L	44	**	**	**	**	**
CV (%)		13.97	7.38	20.00	20.41	1.74
General Average:		3,237	141	40	95	110

When analyzing the productive performance of cultivars in low-lying municipalities, it can be seen that only M 7110 IPRO and BMX Desafio RR had higher grain yields in Maurilândia and Bom Jesus, respectively, in the two agricultural crops. However, in the higher altitude municipalities, the cultivars showed a different behavior, characterizing the presence of a genotype x environment interaction (Cucolotto, Garbuglio, Pipolo, Fonseca Junior, & Kamikoga, 2007). In Rio Verde, the productive performances of BMX Desafio RR, M 7110 IPRO, W 712 RR and W787 RR were significant. In the municipality of Jataí, the productive performances of BMX Desafio RR, M 7739 IPRO and NS 7338 IPRO were significant, while in Montividiu, the highest grain yields were obtained with BMX Potência RR, BMX Prisma IPRO, NA7337 RR, NS 7338 IPRO, and W 787 RR.

Table 4
Mean values of grain yield (kg ha^-1) of transgenic soybean cultivars, under Brazilian Cerrado conditions, in the 2013/14 and 2014/15 crop years.

Cultivars	Crop Year 2013/14										Crop Year2014/15
	MA		BJ		RV		JA		MO		MA		BJ		RV		JA		MO		Mean
BMX Desafio RR	3,550	Bb	4,463	Aa	2,650	Ca	4,688	Aa	4,700	Aa	1,691	Cb	3,153	Ba	2,828	Ba	4,564	Aa	2,669	Bb	3,495
BMX Ponta IPRO	3,613	Bb	4,363	Aa	2,625	Ca	3,750	Bc	4,625	Aa	2,735	Ba	2,678	Bb	1,418	Cb	4,734	Aa	2,375	Bb	3,291
BMX Potência RR	3,688	Bb	4,350	Aa	2,338	Ca	4,338	Ab	4,363	Aa	2,294	Ca	2,600	Cb	1,194	Dc	4,415	Aa	3,389	Ba	3,297
BMX Prisma IPRO	3,713	Ab	3,400	Ac	1,925	Bb	3,925	Ac	4,275	Aa	1,880	Bb	3,658	Aa	1,670	Bb	3,564	Ab	3,766	Aa	3,178
M 7110 IPRO	4,100	Ba	4,988	Aa	2,513	Da	3,575	Cc	5,025	Aa	2,381	Ba	1,920	Bc	2,338	Ba	4,646	Aa	2,848	Bb	3,433
M 7739 IPRO	4,281	Ba	3,963	Bb	2,463	Ca	5,238	Aa	4,788	Aa	1,489	Cb	3,445	Ba	1,861	Cb	4,560	Aa	2,976	Bb	3,506
NA 5909 RR	3,238	Bb	3,763	Bb	1,900	Cb	4,150	Ab	4,338	Aa	2,738	Ba	1,070	Cd	859	Cc	4,035	Ab	2,208	Bb	2,830
NA 7337 RR	3,400	Bb	1,475	Cd	1,650	Cb	3,500	Bc	4,544	Aa	2,563	Ca	3,336	Ba	1,483	Db	4,265	Aa	3,178	Ba	2,939
NS 7000 IPRO	3,338	Bb	3,613	Bb	2,163	Cb	4,175	Ab	4,388	Aa	2,494	Ba	2,461	Bb	2,230	Ba	4,524	Aa	2,836	Bb	3,222
NS 7338 IPRO	4,125	Ba	3,875	Bb	2,163	Cb	4,713	Aa	4,525	Aa	1,158	Cb	3,265	Ba	1,623	Cb	4,915	Aa	3,505	Ba	3,387
W 712 RR	3,788	Bb	3,275	Cc	2,350	Da	3,000	Cc	4,438	Aa	2,181	Ba	2,465	Bb	2,475	Ba	4,230	Aa	2,340	Bb	3,054
W 787 RR	3,775	Ab	2,938	Bc	2,325	Ba	4,338	Ab	3,888	Aa	2,445	Ba	3,039	Aa	2,259	Ba	3,570	Ab	3,654	Aa	3,223
Mean	3,717		3,705		2,255		4,116		4,491		2,171		2,757		1,853		4,335		2,979

• Means followed by the same capital letter in the rows and lowercase in the columns do not differ from one another by the Scott-Knott test, at 5% probability. MA: Maurilândia; BJ: Bom Jesus; RV: Rio Verde; JA: Jataí; MO: Montividiu.

When analyzing the positioning of soybean cultivars to explore their productive potential, it can be seen that in Jataí, most of the cultivars had higher yields of grains, especially

BMX Desafio RR, BMX Potência RR, BMX Prisma IPRO, M 7739 IPRO, NA 5909 RR, NS 7000 IPRO, NS 7338 IPRO, and W 787RR. It should be noted that the BMX Prisma IPRO produced similar grain yield in the municipalities of Bom Jesus and Montividiu. Similar factors occurred with the cultivar W 787 RR in Montividiu.

In the evaluation of the performance of the cultivars in each municipality, it is observed that BMX Desafio RR conferred higher yields of grains in Bom Jesus de Goiás, Rio Verde, and Jataí, in two consecutive agricultural harvests (Table 4). This demonstrates the good performance of the cultivar in low, medium and high altitude regions, respectively. The highest performances in regions of higher altitude were observed for BMX Desafio RR (Rio Verde and Jataí), W 787 RR (Rio Verde and Montividiu), and NS 7338 IPRO (Jataí and Montividiu).

The highest yields of grains obtained in the regions of higher altitude are due to the lower average nocturnal temperatures, which allows the greater storage of photoassimilates because of the reduction of respiration rate in the plants (Daroish, Hassan, & Ahad, 2005). Consequently, there is a greater amount of reserves to be transported to the grains, thus contributing to the increase of soybean yield (Fageria & Santos, 2008).

On the other hand, all cultivars, except BMX Desafio RR, showed the lowest grain yields in Rio Verde during both crop years. It was expected that this locality would provide intermediate yield values between the regions of higher and lower altitudes. However, the irregular distribution of rainfall (Figure 1c and d) coinciding with the reproductive stages of the cultivar negatively influenced the development of the soybeans, which reduced grain yield (Canfalone, & Navarro Dujmovich, 2012).

It is important to note that the highest grain yields in the higher altitude regions were obtained, mostly by longer cycle cultivars. Therefore, it can be observed that the longer the development period of the plants, either in the vegetative or reproductive phases, associated with a lower night temperature condition, makes it possible to obtain higher yields of grains (Rocha & Vello, 1999).

The analysis of the weight of one thousand grains verified effects for different soybean growing environments during both crop years, except for Montividiu, which presented similar and superior results to the other environments (Table 5). Notably, the heavier weights of the one thousand grains of the cultivars BMX Desafio RR, M 7110 IPRO, and W 712 RR, in Rio Verde, contributed to higher grain yields. In this case, there was no direct relationship between the maturation group and the weight of a thousand grains. Most likely, this result can be attributed to the phenotypic plasticity of soybean cultivars in compensating the yield components (Peluzio, Afférri, Monteiro, Melo, & Pimenta, 2010).

Table 5
Mean values of the thousand grains (grams) (GMO) and weight of transgenic soybean cultivars under Cerrado conditions in the 2013/14 and 2014/15 crop years in Brazil.

Cultivars	Crop Year 2013/14										Crop Year2014/15
	MA		BJ		RV		JÁ		MO		MA		BJ		RV		JA		MO		Mean
BMX Desafio RR	153	Ab	127	Bb	151	Aa	162	Ab	145	Ac	130	Ba	163	Aa	99	Ca	135	Bc	171	Aa	143
BMX Ponta IPRO	135	Bc	150	Aa	152	Aa	145	Bc	158	Ac	94	Bc	143	Ab	85	Bb	145	Ab	157	Ab	136
BMX Potência RR	138	Bc	150	Aa	139	Ba	145	Bc	156	Ac	112	Cb	170	Aa	88	Db	141	Bc	158	Ab	140
BMX Prisma IPRO	126	Bd	119	Bb	125	Bb	118	Bd	172	Ab	121	Bb	163	Aa	99	Ca	121	Bd	162	Ab	132
M 7110 IPRO	156	Bb	168	Aa	149	Ba	158	Bb	175	Ab	112	Cb	146	Bb	103	Ca	169	Aa	178	Aa	151
M 7739 IPRO	148	Bb	128	Cb	149	Ba	154	Bb	187	Aa	117	Cb	151	Cb	85	Db	142	Bc	177	Aa	144
NA 5909 RR	135	Bc	156	Aa	150	Ba	139	Bc	170	Ab	104	Cc	113	Cc	83	Db	136	Bc	153	Ab	134
NA 7337 RR	117	Bd	93	Cc	115	Bb	140	Bc	146	Ac	134	Ba	144	Bb	81	Cb	147	Bb	177	Aa	129
NS 7000 IPRO	166	Ba	160	Ba	161	Ba	177	Aa	190	Aa	114	Db	140	Cb	101	Da	160	Ba	177	Aa	154
NS 7338 IPRO	141	Bc	135	Bb	153	Aa	155	Ab	155	Ac	110	Bb	159	Aa	96	Ba	152	Ab	170	Aa	142
W 712 RR	166	Ba	154	Ba	164	Ba	170	Ba	181	Aa	110	Cb	148	Cb	112	Ca	153	Bb	169	Aa	153
W 787 RR	138	Ac	132	Ab	124	Ab	134	Ac	148	Ac	145	Ba	152	Bb	98	Da	123	Cd	178	Aa	137
Mean	143		139		144		150		165		117		149		94		144		169

• Means followed by the same capital letter in the rows and lowercase in the columns do not differ from one another by the Scott-Knott test, at 5% probability. MA: Maurilândia; BJ: Bom Jesus; RV: Rio Verde; JA: Jataí; MO: Montividiu.

It can be assumed that the higher number of pods would provide a higher number of grains per plant, as observed for M 7739 IPRO cultivated in regions of lower altitude (Maurilândia and Bom Jesus de Goiás). However, the contribution of this variable in increasing grain yield was only observed for the cultivar NA 7337 RR in Montividiu, during both crop years (Table 6). Probably this lack of relationship between the components of the yield can be attributed to the phenotypic plasticity of the evaluated cultivars, as observed in other research studies (Navarro Júnior & Costa, 2002; Mauad et al., 2011).

Table 6
Mean values of the number of pods (NP) of transgenic soybean cultivars, under Brazilian Cerrado conditions, in the 2013/14 and 2014/15 crop years.

Cultivars	Crop Year 2013/14										Crop Year 2014/15
	MA		BJ		RV		JÁ		MO		MA		BJ		RV		JA		MO		Mean
BMX Desafio RR	33	Ab	35	Ab	27	Ab	31	Ab	37	Ab	41	Ab	43	Ab	39	Aa	40	Ab	38	Ac	36
BMX Ponta IPRO	43	Aa	42	Ab	38	Aa	35	Ab	35	Ab	29	Ac	42	Ab	31	Aa	32	Ab	38	Ac	36
BMX Potência RR	37	Ab	36	Ab	33	Ab	34	Ab	41	Ab	25	Bc	45	Ab	39	Aa	49	Aa	33	Bc	37
BMX Prisma IPRO	44	Ba	65	Aa	33	Cb	50	Ba	35	Cb	52	Ab	47	Ab	34	Aa	45	Ab	43	Ab	45
M 7110 IPRO	47	Aa	39	Ab	35	Aa	33	Ab	42	Ab	27	Ac	41	Ab	35	Aa	33	Ab	33	Ac	36
M 7739 IPRO	52	Aa	60	Aa	37	Ba	52	Aa	34	Bb	64	Aa	61	Aa	38	Ba	54	Aa	48	Bb	50
NA 5909 RR	26	Ab	34	Ab	29	Ab	27	Ab	40	Ab	26	Ac	23	Ac	20	Ab	34	Ab	29	Ac	29
NA 7337 RR	54	Ba	73	Aa	43	Ca	49	Ca	59	Ba	49	Bb	66	Aa	41	Ca	34	Cb	59	Aa	53
NS 7000 IPRO	31	Ab	32	Ab	28	Ab	33	Ab	31	Ab	27	Bc	40	Ab	39	Aa	29	Bb	26	Bc	32
NS 7338 IPRO	38	Ab	43	Ab	28	Bb	33	Bb	31	Bb	44	Bb	46	Bb	37	Ba	57	Aa	45	Bb	40
W 712 RR	48	Aa	47	Ab	42	Aa	42	Aa	50	Aa	31	Bc	50	Ab	40	Aa	32	Bb	42	Ab	42
W 787 RR	50	Ba	65	Aa	36	Ba	40	Ba	42	Bb	52	Bb	54	Ba	44	Ba	64	Aa	45	Bb	49
Mean	42		48		34		38		40		39		46		36		42		40

• *Means followed by the same capital letter in the rows and lowercase in the columns do not differ from one another by the Scott-Knott test, at 5% probability. * MA: Maurilândia; BJ: Bom Jesus; RV: Rio Verde; JA: Jataí; MO: Montividiu.

It is also important to note that the contribution of the number of pods per plant in increasing grain yield can be observed for cultivars M 7110 IPRO, W 712 RR and W 787 RR in Rio Verde, for M 7739 IPRO in Jataí and for NA 7337 RR in Montividiu, in both agricultural crops (Tables 4 and 6). In both crop years, cultivar M 7739 IPRO obtained the largest number of pods in all environments, except in Montividiu. This cultivar, together with NA 7337 IPRO and W 787 RR, formed the largest number of pods in Bom Jesus de Goiás and Rio Verde, and the latter also stood out in Jataí.

The longest cycle contributed to obtaining higher grain yields for cultivars W 787 RR (in Rio Verde and Montividiu) and for BMX Prisma IPRO in Montividiu. Conversely, the cultivar NA 5909 RR was the most precocious in all the localities. Together with this cultivar, the early behavior of BMX Potência RR in Maurilândia was also outstanding (Table 7).

Table 7
Mean values of the number of grains (NG) of transgenic soybean cultivars, under conditions of the Brazilian Cerrado, in the 2013/14 and 2014/15 crop years.

Cultivars	Crop Year 2013/14										Crop Year 2014/15
	MA		BJ		RV		JA		MO		MA		BJ		RV		JA		MO		Mean
BMX Desafio RR	67	Ab	84	Ab	68	Aa	78	Ab	93	Ab	103	Ac	110	Ab	94	Aa	113	Ab	88	Ab	90
BMX Ponta IPRO	103	Aa	108	Ab	99	Aa	92	Ab	89	Ab	77	Bd	109	Ab	79	Ba	76	Bc	99	Aa	93
BMX Potência RR	91	Ab	91	Ab	89	Aa	80	Ab	97	Aa	57	Bd	97	Ab	89	Aa	112	Ab	78	Bb	88
BMX Prisma IPRO	109	Ca	156	Aa	88	Ca	123	Ba	89	Cb	130	Ab	121	Aa	78	Ba	112	Ab	109	Aa	111
M 7110 IPRO	112	Aa	98	Ab	86	Aa	82	Ab	105	Aa	73	Ad	106	Ab	91	Aa	82	Ac	84	Ab	92
M 7739 IPRO	114	Aa	130	Aa	84	Ba	117	Aa	79	Bb	157	Aa	140	Aa	79	Ca	112	Bb	111	Ba	112
NA 5909 RR	60	Ab	80	Ab	67	Aa	61	Ab	90	Ab	61	Ad	54	Ac	46	Ab	80	Ac	69	Ab	67
NA 7337 RR	106	Ba	129	Aa	86	Ba	93	Bb	120	Aa	98	Bc	136	Aa	81	Ba	82	Bc	122	Aa	105
NS 7000 IPRO	74	Ab	78	Ab	66	Aa	80	Ab	75	Ab	67	Bd	102	Ab	94	Aa	70	Bc	63	Bb	77
NS 7338 IPRO	86	Ab	95	Ab	67	Aa	78	Ab	74	Ab	99	Bc	111	Bb	83	Ba	135	Aa	104	Ba	93
W 712 RR	110	Aa	113	Ab	99	Aa	97	Ab	114	Aa	75	Bd	116	Ab	94	Aa	73	Bc	99	Aa	99
W 787 RR	119	Aa	140	Aa	83	Ba	93	Bb	101	Ba	124	Bb	126	Ba	96	Ba	153	Aa	111	Ba	115
Mean	96		108		82		89		94		94		111		84		100		95

• Means followed by the same capital letter in the rows and lowercase in the columns do not differ from one another by the Scott-Knott test, at 5% probability. MA: Maurilândia; BJ: Bom Jesus; RV: Rio Verde; JA: Jataí; MO: Montividiu.

It was expected that the localities, due to the difference in altitude, and consequently temperature, would influence the cycle of soybean varieties, even though they were all cultivated in the microregions of 301 and 302. However, this was not observed; each variety reached physiological maturity in all environments within the same number of days (Table 8). This can be justified by the juvenile period characteristic of each cultivar, which defines the rate of maturation (Destro, Carpentieri-Pípolo, Kiihl, & Almeida, 2001; Sediyama, 2009). However, in all localities, a differentiated development was observed, with a longer cycle for NA 7337 RR (Maurilândia, Jataí, and Montividiu), BMX Prisma IPRO (except in Rio Verde) and W 787 RR (in all localities).

Table 8
Mean values of the cycle (days) of transgenic soybean cultivars under Cerrado de Goiás, in the 2013/14 and 2014/15 crop years.

Cultivars	Crop Year 2013/14										Crop Year 2014/15
	MA		BJ		RV		JÁ		MO		MA		BJ		RV		JA		MO		Mean
BMX Desafio RR	109	Ac	114	Ab	115	Ab	111	Ab	111	Ac	108	Ac	110	Ac	109	Ae	114	Ac	112	Ac	111
BMX Ponta IPRO	103	Ae	110	Ad	106	Ad	106	Ac	111	Ac	99	Af	110	Ac	110	Ae	111	Ad	103	Af	107
BMX Potência RR	103	Ae	107	Ae	106	Ad	103	Ad	102	Ae	102	Ae	102	Ae	97	Ah	107	Ae	106	Ae	103
BMX Prisma IPRO	114	Ab	119	Aa	118	Aa	116	Aa	120	Aa	118	Aa	119	Aa	118	Ab	121	Aa	122	Aa	118
M 7110 IPRO	103	Ae	111	Ad	108	Ad	106	Ac	108	Ad	103	Ae	107	Ad	111	Ad	108	Ae	107	Ae	107
M 7739 IPRO	110	Ac	116	Ab	117	Aa	117	Aa	118	Ab	117	Aa	116	Ab	115	Ac	117	Ab	121	Aa	116
NA 5909 RR	98	Af	104	Ae	99	Ae	103	Ad	99	Af	99	Af	98	Af	94	Ai	102	Af	103	Af	100
NA 7337 RR	117	Aa	117	Aa	119	Aa	116	Aa	116	Ab	117	Aa	115	Ab	114	Ad	120	Aa	121	Aa	117
NS 7000 IPRO	102	Ae	110	Ad	106	Ad	105	Ac	109	Ad	101	Af	109	Ac	107	Af	103	Af	105	Af	105
NS 7338 IPRO	109	Ac	113	Ac	112	Ac	113	Ab	112	Ac	112	Ab	109	Ac	112	Ad	115	Ac	116	Ab	112
W 712 RR	107	Ad	109	Ad	107	Ad	105	Ac	103	Ae	105	Ad	105	Ad	103	Ag	108	Ae	109	Ad	106
W 787 RR	119	Aa	119	Aa	119	Aa	114	Aa	122	Aa	116	Aa	119	Aa	121	Aa	120	Aa	120	Aa	119
Mean	108		112		111		110		111		108		110		109		112		112

• Means followed by the same capital letter in the rows and lowercase in the columns do not differ from one another by the Scott-Knott test, at 5% probability. MA: Maurilândia; BJ: Bom Jesus; RV: Rio Verde; JA: Jataí; MO: Montividiu.

There was no precocity relation with higher grain yield, except for BMX Potência RR, cultivated in Jataí, in both crop years (Tables 4 and 8). The advantage of precocity is that corn (Silva, Teixeira, Martins, Simon, & Francischini, 2014; Silva, Francischini, & Goulart, 2015) and sorghum can be cultivated after the soybean crop (second or winter season crop), which can increase producer income from annual crops. This is a common practice for producers in the central - west region, especially since many producers already have the infrastructure and machinery necessary for the cultivation of soy and cereal in succession (Silva, Francischini, & Martins, 2015).

Searching for earlier yielding cultivars, with the aim of implementing a second or winter season crop may not be an adequate strategy in having higher yields of soybean grains. During this study, it was observed that the early cultivars did not provide higher grain yields, contrary to that observed for the longer cycle cultivars.

Therefore, the adoption of soybean cultivars with differing cycles, independent of the transgenic technology, is important consideration for soybean cultivation in the Cerrado, as it will help the producer to schedule the harvest at different times. In this way, the diversification of cultivars is fundamental to the sustainability of soybean cultivation, since it allows the exploration of genetic variability as a form of phytosanitary management, or even as a strategy to escape water stresses, which is common in the central - west region of Brazil.

Conclusion

The following cultivars were highlighted for grain yield in higher altitude environments: BMX Desafio RR, M 7110 IPRO, W 712 RR and W 787 RR in Rio Verde; BMX Desafio RR, M 7739 IPRO, and NS 7738 IPRO in Jataí; BMX Potência RR, BMX Prisma IPRO, NA 7337 RR, NS 7338 IPRO, and W 787 RR in Montividiu.

The higher yields were independent of transgenic technology and the localities didn´t influence the cycle of the cultivars.

The greater precocity of the cultivars didn´t contribute to increases grain yield, as opposed to medium and longer cycle cultivars, especially in higher altitude locations.

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Publication Dates

• Publication in this collection
  23 Sept 2019
• Date of issue
  Jan-Dec 2019

History

• Received
  18 Dec 2017
• Accepted
  22 Mar 2018