The research was carried out on localities with predominantly “Kancab” (Maya), Luvisol ferric; the exceptions were Valle de Quetzalcoatl and the Experimental Site Ezdná, whose soils were “Akalché” and “Yaaxhom” (Maya), which correspond to Vertisol gleyco and Luvisol chromic soils, respectively [3]. The climate in the study locations is tropical rainy A (W) with rain in summer, with an average temperature of 24˚C to 28˚C and an average annual rainfall of 900 to 1200 mm [4] [5].

For this research, localities from the northern and central regions of the state of Campeche were selected in which the largest area of maize produced in soils worked with machinery is concentrated. The municipalities that comprise these regions were: Calkiní, Hecelchakán, Hopelchén, Tenabo, Campeche and Champotón. The names of the study locations where the performance trials and the demonstration plots were established, as well as their geographical location are indicated in Table 1. As can be seen, the evaluations were carried out in a wide geographic area, but the time quite homogeneous in the type of technological management of the crop. The environmental conditions where the water supply of the plant was 100% based on rainwater from the summer and autumn seasons.

In this study, the yield results obtained in 30 white grain and 16 yellow grain hybrids were analyzed (Table 2). These hybrids were selected from a group of 62 cultivars that were evaluated in the state of Campeche, in the period from 2011 to 2015 with the objective of knowing their performance behavior and transferring the results to the producers. The yield data were obtained by sampling carried out in plots of cooperating producers, which the researchers established in order to transfer results to the producers and other users of the technology; as well as performance trials developed for the purpose of research and validation of the behavior of commercial and experimental corn hybrids. In order to achieve greater precision in the recommendations it was decided to select for this study only those hybrids that were evaluated at least four times (four years, or four different locations), which would have the highest number of repetitions in each [6] [7] [8].

For the technological management of the crop, the recommendations of the Technological Package published by the National Institute of Forestry, Agriculture

and Livestock Research (INIFAP) to produce seasonal maize in the state of Campeche were used [9]. The sowing dates for the years 2011 to 2016 were distributed in the range of July 5 to August 27; the most advanced date corresponded to the year 2011 and the most delayed corresponded to the year 2015. In the preparation of the soil, of all the options that were presented given the variability in localities and years, the one that predominated was the use of two traces (semi tracing—heavy and agricultural tracking), which was complemented with the application of herbicides before planting. The density of sowing that was used was 70 thousand seeds per hectare. In fertilization the dose of 100 kg of DAP per hectare was applied to the planting, plus 250 kg of Urea per hectare at 25 - 30 days of age of the plant. For the control of weeds the use of Nicosulfuron + Picloram + a hilling or weeding prevailed. In pest control there was a predominance of an application of emamectin benzoate. For the determination of the cost the harvest with combined machine was considered. Regarding the insurance, in order to obtain the total cost of the crop, the payment was considered without the government subsidy.

In this study they used the methods of demonstration plots and performance trials. The demonstration plots were Modules where different materials were validated at the same time. In them the “fringe arrangement” with a variable number of furrows was used, but of equal length (100 to 200 m) according to the shape of the cooperating producer’s plot. In these plots the yield was estimated from samples located in “five of golds”, consisting of harvesting in each selected site, two furrows of eight meters in length. In the performance trials the arrangement was of random blocks with four repetitions, the groove width was invariably 80 cm; the experimental plot was four furrows eight meters long. The yield in these tests was obtained by harvesting the useful plot, which were the two central rows.

The study variable was grain yield adjusted to 14% moisture [10].

At the time of harvest, the plants and ears of the trial plot were counted, or in the sample (demonstration plot); with these data, the correction factor “ears per plant” (FCm/pl) was estimated. Only plants with complete competence were harvested. The sample of ears of corn was weighed to determine the total weight per plot/sample (Total weight). An average ear was selected in each case and weighed and shelled, calculating the grain percentage correction factor (FC% gr) and the moisture content (FC 14% hum) [11].

In the cabinet the weight was determined by plot or sample adjusted to 14% humidity, number of ears per plant, percentage of grain and the humidity correction factor. Subsequently, the area per plant and the harvested area were calculated. Finally, the weight per plot was transformed to Grain yield at 14% moisture in kilograms per hectare.

Weight per plot (kg 14% hum.) = (Total weight) × (FCmz/plant) × (FC% grain) × (FC14% hum.)

where FC14% hum = ((100 − field hum)/86).

Area per plant = ((12,500 m/70,000 plants) × 0.8 m) = 0.14286 m²/plant

where 12,500 is the amount of linear meters that there is in a hectare according to the furrow width of 0.8 m and 70,000 plants is the density of sowing.

Harvested area = (plants harvested on the plot or sample) × 0.14286 m²

Grain yield at 14% of hum. (kg·ha⁻¹) = (10,000) × (Weight per plot at 14% of hum.)/Harvested area

Three types of statistical analysis were performed: a regression analysis to determine the relationship between the amount of rainfall accumulated and the grain yield in the different years of study; an analysis under the completely random design, for the average grain yield of the study years; in addition to the analysis with the completely random design for hybrids according to their grain color [12].

In relation to the prevailing climate in the study area, Figure 1 shows that incident solar radiation registered a decrease from the beginning to the end of the crop cycle; starting with values of 419 and 440 w/m² in July and August, respectively, and 305 w/m² in December. On the other hand, the average temperature had a tendency similar to solar radiation, with values of 28˚C and 27˚C in July and August, respectively, and 23˚C in December. On the other hand, rainfall data from the central region of the state of Campeche, in the years in which the

study was carried out, indicated that the average accumulated precipitation between planting and the physiological maturity of the grain was 571 mm, of which 314 mm occurred between sowing and flowering and 256 mm between flowering and the physiological maturity of the grain (Table 3). Also, in the aforementioned time interval, the year 2013 registered the most pronounced rainfall deficiency in the reproductive phase, with only 164 mm; while 2012 and 2015 presented the lowest values in the vegetative phase, with 242 and 240 mm, respectively. The relationship between total precipitation and yield is described in Figure 2, whose model was highly significant, indicating that yield values above 5200 kg are obtained with 530 to 660 mm of rain, since lower and higher values of rainfall reduce the Grain yield.

In this study it was also observed that the behavior of the crop followed a pattern that is schematized in Figure 3, where the stages of flowering, physiological maturity and grain drying, occurred on average at 55, 90 and 135 days, respectively. In this scheme, the most critical time interval of the plant was represented with red color in terms of humidity requirement.

This analysis was made taking the five years of study as treatments and the average performance of the materials that were evaluated in the same year, as repetitions. There was a significant difference high (p = 0.01) between the treatments (Table 4), and the DMS test (p = 0.05) indicated that the years 2014 and 2012 were statistically equal, with 5500 and 5481 kg·ha⁻¹ and higher in 2013 and 2015, which registered 4718 and 4646 kg·ha⁻¹, respectively.

The different varieties used in this study were grouped by their color of the grain to analyze separately the yield of 30 varieties of white grain and the 16 of yellow grain. An analysis of variance was used in which the treatments were the hybrids

*significant difference (p = 0.05), **highly significant difference (p = 0.01).

and the repetitions in the years and/or the localities where they were evaluated; these results are shown in (Table 5). With regard to white grain hybrids, the F test showed significant differences between treatments (p = 0.05), whereas in yellow grain hybrids the differences were highly significant (p = 0.01). The above indicated at least one of the treatments in each classification behaved differently than the rest of them.

To determine which hybrids showed high and low yield, the separation test was carried out by the DMS method (p = 0.05). The results indicated that SB-309, DK-395, DK-393 and DAS-2382 were the highest yield white-grain hybrids (Table 6); while 9107Y, SP-525A, 2B688, DK-7500 and P4226A were the yellow grain hybrids who excelled in this aspect (Table 7). On the other hand, white grain hybrids, DASUR 100, IMPARABLE and H-515 were the ones that showed the lowest yields; whereas, in those with yellow grain, those with the lowest yield were SBA-410 and SBA-404.

*significant difference (p = 0.05), **highly significant difference (p = 0.01).

*Significant minimum difference.

*Significant minimum difference.

The total cost to grow one hectare of corn at prices updated to 2018 amounted to $10,961.00, and for the purposes of financial analysis this information was summarized in Table 8, which presents the specific cost for the different components included in the Technology Package recommended. As can be seen, fertilization, sowing and soil preparation are the items with the highest value; this is due to the high cost of fertilizers, seed and fuels.

The financial analysis was carried out separately for hybrids of white and yellow cattle (Table 9), considering the groups of high, intermediate and low productivity. The Income (I), the Benefit (B), the Benefit-cost relationship (B/C), as well as the equilibrium point (PE) were calculated (Table 9) [13] [14] [15]. The average price of one ton of grain was estimated at $3300.00 for both types of grain. The sources of information were the grain collectors, and the Services Agency for the Marketing and Development of Agricultural Markets of the city of San Francisco de Campeche [16]. The values in the benefit per hectare in the white grain hybrids were from 7219 to 609 pesos; while in the yellow grain from 7410 to −916 pesos. Due to the above, the profitability was positive in the intermediate and high productivity strata in both types of grain, with gains of 35 to 66 cents per peso invested in the white grain and from 43 to 68 cents in the yellow grain [17]. In the low productivity stratum, profitability was negative for yellow grain hybrids and had low values in white grain hybrids. Finally, regardless of the color of the grain and the stratum, the yield at the equilibrium point was 3321 kg·ha⁻¹.

*Does not include the government subsidy.