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Objective: To analyze the race diversity and geographic distribution of the native maize landraces currently cropped at southern Nuevo León, México. Design/Methodology/Approach: Data was obtained from 41 accessions which represent the commercial production in the dry land area, where fertilization and pest control are scarcely used. Landraces were classified according to the CONABIO guidelines for ear traits. Results: The measured accessions correspond to seven maize races and to seven interracial crosses. The two most frequent maize races were Ratón and Cónico Norteño, mainly located in the dry areas with less rain. Study Limitations/Implications: Three races, Celaya, Tablilla de Ocho and Elotes Cónicos, had not been previously reported; while two formerly reported races Tabloncillo and Olotillo, were no longer found. This study did not include the grain-colored accessions. Findings/Conclusions: Three collections stood out for producing large cobs with large kernels, thus showing a high yield potential. The maize landraces harvested in dryland areas might offer advantages to be grown under harsh environments or be used as gene donors for drought tolerance. [ABSTRACT FROM AUTHOR]

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The aim of this study was the characterization of chromatic, nutritional and nutraceutical properties of fifteen native maize genotypes of the races: conico norteño, elotes cónicos, raton, conico norteño × elotes cónicos, raton × elotes cónicos, Celaya × elotes cónicos, elotes cónicos × conico norteño from the northeast of Mexico. The results showed that the values of the color parameters L*, C* and h in genotypes range from 25.13 to 63.64, 2.41 to 33.58 and 14.36 to 359.19, respectively. The percentage of nutritional component varied from carbohydrates (71.30–74.88), protein (9.72–12.57) and moisture (7.98–9.67). The samples were rich in P, K, Mg, Zn and Fe. The total phenols content (free + bound) ranged from 349.39 to 485.71 mgGAE/100 g, showing bound fractions higher content than free fractions. The total flavonoids (free + bound) were from 24.00 to 105.75 mgCE/100 g, and for eight of the genotypes the bound fractions were higher than free fractions. Condensed tannins were only found in free fractions with values ranging from 33.70 to 158.55 mgCE/100 g. Total anthocyanins ranged from 1.38 to 74.52 mgC3GE/100 g. In HPLC analysis, ferulic acid (103.34–164.90 mg/100 g) was the main phenolic compound followed by coumaric acid (5.57–15.52 mg/100 g) and they were only identified in bound extracts. Finally, the antioxidant capacity (free + bound) expressed in µmolTE/100 g was from 1127.70 to 1875.70, 2826.90 to 4263.90, 730.94 to 1340.65 and 3484.80 to 5592.60 in DPPH, ABTS, FRAP and ORAC, respectively, and IC50 to DPPH and ABTS were expressed in mg/mL. In conclusion, significant correlation was found between chromatic versus antioxidant capacity, and anthocyanin content. In addition, higher phenolic content were found in bound extracts, and a genetic diversity was observed between maize genotypes. [ABSTRACT FROM AUTHOR]

The specific (SCA) and general combinatorial aptitude (GCA) are used to identify hybrid combinations between inbred lines with higher or lower yield than that expected from the average behavior of the parental lines. The objective of this study was to evaluate the GCA of eight lines and the SCA of their inbreeding. We hypothesized that crosses between lines with contrasting characteristics would produce outstanding hybrids. During autumn 2011 the crosses were formed and in spring 2012 evaluated at the Marín experimental field, Universidad Autónoma de Nuevo León, México. The eight evaluated inbred lines were in a complete blocks experimental design at random with three repetitions. Genetic analysis was performed with the design II North Carolina mating from Comstock and Robinson. The progenitors, considered as males M-16 (4.74 t ha-1), M-11 (4.60 t ha-1) and M-14 (4.21 t ha-1) and females H-8 (4.26 t ha-1), H-2 (4.15 t ha-1) and H-4 (4.13 t ha-1) showed the greatest effects of GCA. Major effects on SCA were observed in the H-8×M-16 (4.99 t ha-1), H-8×M-11 (4.83 t ha-1) and H-2×M16 (4.78 t ha-1) crosses. The additive variance for grain yield was 0.03 and exceeded the dominance variance (-0.34); heritability in the strict sense was 7.65% and female variance (0.0075) was higher than that of males (0.0012). [ABSTRACT FROM AUTHOR]

Mexico, the center of origin of maize (Zea mays L.), has taken actions to preserve the identity and diversity of maize landraces and wild relatives. Historically, spatial isolation has been used in seed production to maintain seed purity. Spatial isolation can also be a key component for a strategy to minimize pollen-mediated gene flow in Mexico between transgenic maize and sexually compatible plants of maize conventional hybrids, landraces, and wild relatives. The objective of this research was to generate field maize-to-maize outcrossing data to help guide coexistence discussions in Mexico. In this study, outcrossing rates were determined and modeled from eight locations in six northern states, which represent the most economically important areas for the cultivation of hybrid maize in Mexico. At each site, pollen source plots were planted with a yellow-kernel maize hybrid and surrounded by plots with a white-kernel conventional maize hybrid (pollen recipient) of the same maturity. Outcrossing rates were then quantified by assessing the number of yellow kernels harvested from white-kernel hybrid plots. The highest outcrossing values were observed near the pollen source (12.9% at 1 m distance). The outcrossing levels declined sharply to 4.6, 2.7, 1.4, 1.0, 0.9, 0.5, and 0.5% as the distance from the pollen source increased to 2, 4, 8, 12, 16, 20, and 25 m, respectively. At distances beyond 20 m outcrossing values at all locations were below 1%. These trends are consistent with studies conducted in other world regions. The results suggest that coexistence measures that have been implemented in other geographies, such as spatial isolation, would be successful in Mexico to minimize transgenic maize pollen flow to conventional maize hybrids, landraces and wild relatives. [ABSTRACT FROM AUTHOR]

Charcoal rot ( Macrophomina phaseolina) is a major disease of beans ( Phaseolus vulgaris L.) in Mexico. The use of germplasm combining high-yield stability with resistance to drought and charcoal rot could reduce damage from this disease. In this study, we compared the Eberhart and Russell method and the Additive Main Effect and Multiplicative Interaction (AMMI) model plus biplot analysis for measuring grain yield (GY) and charcoal rot resistance (CHRR) stabilities in 98 F8 : 10 recombinant inbred lines (RILs) derived from a cross between bean adapted to the tropics (BAT) 477 (resistant) × Pinto UI-114 (susceptible). Experiments were conducted from 2007 to 2009 in Isla, Cotaxtla, Río Bravo and Díaz Ordaz, México, under irrigated or terminal drought conditions. anova detected significant differences (P ≤ 0.05) in GY and CHRR among environments, genotypes and genotype × environment interactions (GEI). Most RILs showed good responses to unfavourable environments based on GY (48) and CHRR (40). AMMI anova s for both traits showed that all sources of variation in the model accounted for approximately 49% of the total squared sum. For the first principal component (PC1), we found 13 RILs that were stable for GY, and for the second (PC2), we found 9 that were stable for GI. For CHRR, we detected 14 stable RILs (PC1) and eight (PC2). Biplot analysis showed the largest vectors for Díaz Ordaz (irrigated and drought, 2008), where the highest and most variable GYs were detected. The shortest vectors were found in Isla (drought, 2007) and Río Bravo (irrigated and drought, 2008), where the lowest and least variable GY were found. We found differential responses of RILs to locations, years and soil humidity conditions as well as significant GEI based on GY and CHRR. The two methods were complementary, and both gave us information to select stable, high-yield germplasm associated with resistance to charcoal rot disease. [ABSTRACT FROM AUTHOR]

The objective of this work was to identify the molecular and phenotypic variability among maize populations Pinto Amarillo and Liebre in Nuevo Leon, Mexico. The phenotypic characterization experiment was established in spring 2009. The variables registered were plant height, days to male and female flowering, number of rows per ear, kernels per row of ears, length and diameter of the corn ear. For the molecular characterization of the 30 populations, the seeds were planted in February 2010 in pots with peat-moss. At 30 days after planting all the leaves were collected and used in AFLP. A cluster analysis was conducted using UPGMA method. Three groups were identified; twelve populations of Pinto Amarillo and three of Liebre. The landraces within each group were associated more to races of maize more than to location. [ABSTRACT FROM AUTHOR]

Sorghum (Sorghum bicolor (L.) Moench) is cultivated in regions with frequent drought periods and high temperatures, conditions that have intensified in the last decades. One of the most important photosynthetic components, sensible to hydric stress, is maximum quantum yield for photosystem II (PSII, or Fv/Fm). The objective of the present study was to identify sorghum genotypes with tolerance to hydric and heat stress. The treatments were hydric status (hydric stress or non-hydric stress (irrigation)), the plant's developmental stages (pre or post-anthesis), and six genotypes. The response variables were Fv/Fm; photosynthetic rate (PN); stomatal conductance (gs); transpiration rate (E); relative water content (RWC); damage to cell membrane (DCM) at temperatures of 40 and 45 °C; and agronomic variables. The experiment was conducted in pots in open sky in Marín, N.L., in the dry and hot northeast Mexico. The treatment design was a split–split plot design, with three factors. Hydric stress diminished the functioning of the photosynthetic apparatus by 63%, due to damage caused to PSII. Pre-anthesis was the most vulnerable stage to hydric stress as it decreased the weight of grains per panicle (85%), number of grains per panicle (69%), and weight of 100 grains (46%). Genotypes LER 1 and LER 2 were identified as tolerant to hydric stress, as they had lower damage to PSII; LER 1 and LEB 2 for their superior RWC; and LER 1 as a thermo tolerant genotype, due to its lower DCM at 45 °C. It was concluded that LER 1 could have the potential for both hydric and heat stress tolerance in the arid northeast Mexico. [ABSTRACT FROM AUTHOR]

Melanaphis sacchari Zehntner (Hemiptera: Aphididae) is an important destructive pest in forage sorghum in Nuevo León, Mexico. This study was conducted to identify predatory and parasitoid insect species associated with this pest in Nuevo León, and their impact on its biocontrol. During the monitoring period, identified insects indicated the coexistence of 8 coccinellid species, 2 syrphid species, and 1 chrysopid species. In addition, 2 hymenopteran species were identified. After the insecticide applications, sugarcane aphid population was reduced by about 20.6% (about 14 nymphs per cm2); when the sampling ended, population was reduced by about 70.6% (about 5 nymphs per cm2), thus indicating predator and parasitoid biocontrol. Collected data allowed us to conclude that the biological controllers were responsible for the principal pest population reduction. Overall, results showed that yellow sugarcane aphid predatory and parasitoid species may play an important role in the pest management in sorghum crops in Nuevo León, Mexico. [ABSTRACT FROM AUTHOR]

Charcoal rot caused by Macrophomina phaseolina (MP) is the most important disease that limits sorghum dryland production in northern Tamaulipas, Mexico. Grain yield losses caused by MP are approximately 30%. The objective of this study was to evaluate the response of experimental and commercial hybrids to MP and identify MP tolerant progenitors. Experimental hybrids RB-118 x 435 and RB-27 x 437 showed MP tolerance and grain field similar to commercial checks Pioneer 82G63, Pioneer 84G62, RB-Patrón, Asgrow Z- 400, RB-3030, and DK-47, and greater than Asgrow-Ámbar. Progenitor females that produced tolerant MP hybrids were LRB-118 and R-27, and males Tx-435 and Tx-437. [ABSTRACT FROM AUTHOR]