Diversity of vam in soils used to cultivate sugarcane (Saccharum spp.) in Tabasco, Mexico

E Objective: A study was carried out in the Ingenio Santa Rosalía sugar mill supply area with the aim of identifying the soil subunits cultivated with sugar cane and to quantify the degree of mycorrhization of Saccharum officinarum. Design/Methodology/Approach: Rhizosphere samples were collected at a depth of 0-30 cm and root segments with diameters of ≤ 1 mm and 1-2.0 mm were studied. The intersect method and the fungal structures method were comparatively analyzed to determine the mycotrophic state of the roots. The study also quantified the number of spores in the soils and classified the morpho-species of vesicular-arbuscular mycorrhiza (VAM). Results: The results show that seven soil subunits exist in the area, but the intersect method did not detect differences in colonization by root diameter or by root colonization ( = 68.5%). For its part, the fungal structures method showed differences in colonization between soil subunits ( = 69.5%), being higher in thin roots, and statistical differences wer found for vesicles and spores. At the sites, an average of 696 spores was quantified per 100 g of soil, which indicates a high presence of vesicular-arbuscular mycorrhizal fungi in the study area. Finally, six species of mycorrhizae were identified, of which four are present in various soil subunits: Glomus aff. deserticola, Glomus etunicatum, Glomus viscosum, and Paraglomus occultum. Study Limitations/Implications: This was an exploratory study that indicates the potential of VAM. Findings/Conclusions: The presence of hyphae, vesicles, arbuscules, and spores indicates that there is an active mycotrophic process between VAM and sugarcane cultivation in the soils of the study area.

Suspension of irrigation during the maturation phase of sugarcane (Saccharum spp.) cultivation

Objective: To evaluate if there is an increase in the concentration of sugars in sugarcane grinding stalks as a result of controlled water stress. Design/Methodology/Approach: An experimental plot on cultivar MEX 69-290 was established in 2nd ratoon cycle, on a mollic Gleysol soil in the supply area of ​the​ Pujiltic sugar mill. Five treatments in irrigation suspension were established: T1 = 15 days; T2 = 30 days; T3 = 45 days; T4 = 60 days, and T5 = 75 days of suspension. The treatments were distributed in the field in a gradient plot design, following the slope of the land, with four repetitions within each irrigation strip. Results: The results show that suspending irrigation between 45 and 60 days before harvest increases the quality of the juices as well as the yields of the grinding stalks. In addition, natural precipitation plus irrigation water do not satisfy the water needs of the crop in the area under the scheme followed by the farmers. Study Limitations/Implications: Irrigation rotation. Findings/Conclusions: The authors recommend providing the necessary amount of auxiliary irrigation to satisfy the water demand of the crop during the growth cycle but suspending irrigation at the beginning of the ripening and maturity stage.

DIFFERENTIAL EFFECT OF SALINITY ON GROWTH, NUTRIENT CONCENTRATION AND CHLOROPHYLL IN SUGARCANE VARIETIES MEX 69-290 AND CP 72-2086

Sugarcane (Saccharum spp. hybrids) is moderately sensitive to salinity and the effects on plant performance vary according to stress level and genotype. This study aimed to evaluate the effect of salt stress induced by application of different NaCl levels in the irrigation solution on plant height, indirect index of chlorophylls (SPAD), and macronutrients concentration (N, P, K, Ca, Mg and S) and Na in leaves of two sugarcane varieties: CP 72-2086 and Mex 69-290. The experiment was set in a completely randomized design with a 2×5 factorial arrangement. The study factors were sugarcane variety (CP 72-2086 and Mex 69-290) and NaCl concentration (0.0, 71.8, 143.6, 215.4 and 282.7 mM NaCl). Salinity as a single factor negatively affected plant height, SPAD units and N and P concentration in leaves; Ca concentrations increased, while K, Mg and S remained unaffected by the tested NaCl levels. Mex 69-290 grew higher and concentrated greater levels of N and K. Interactions of factors showed that salinity reduced growth in both varieties, but this reduction was more pronounced in CP 72-2086. SPAD units were also significantly reduced by salinity in both varieties. Concentrations of N and P in leaves decreased in both varieties in response to NaCl, while those of K and Ca increased in Mex 69-290. Concentration of Na was higher in Mex 69-290 which exhibited better performance than CP 72-2086. Sodium concentrations in leaves increased in direct relation to the tested NaCl concentrations. Mex 69-290 reached higher concentrations of Na in leave tissues but displayed better health than CP 72-2086. Thus, the variety Mex 69-290 showed more efficient Na-tolerance mechanisms related to Ca and K concentrations, and an indirect chlorophyll index better than CP 72-2086.

Optimized somatic embryogenesis and plant regeneration in elite Argentinian sugarcane (Saccharum spp.) cultivars

Background Biotechnological breeding of elite sugarcane cultivars is currently limited because of the difficulty of regenerating plants by tissue culture. Here, we report that commercially elite sugarcane genotypes, which are adapted to Argentinian agro-ecological conditions, are capable of being regenerated via indirect somatic embryogenesis. Leaf rolls of five elite genotypes were cultured following two callus induction protocols using different concentrations of 2,4-D as the growth regulator. Embryogenic calluses were regenerated under light conditions. Regenerated plants were subsequently acclimatized in the greenhouse under two acclimatization procedures before being transplanted to the field. Results Four of the five genotypes were able to form somatic embryos following the two induction protocols. The variables related to embryogenic callus production were influenced by the interaction between genotype and culture conditions. For plant regeneration, the embryogenic calluses were further cultured on an IBA-supplemented medium, where we observed a high genotype dependence. Calluses from the four cultivars regenerated a good number of plants. With the procedures described here, we obtained more than 90% of well-acclimatized plants both in the greenhouse and in the field. Conclusions This protocol provides a simple way to regenerate sugarcane plants through indirect somatic embryogenesis. Also, the results confirm that tissue culture ability is highly genotype-dependent in sugarcane. Our findings suggest that these elite cultivars could be good candidates for biotechnological breeding.

Comportamiento agroindustrial de seis variedades de Caña de azúcar (Saccharum spp.) para Panela en Barbosa (Colombia)

En Colombia, la producción de caña de azúcar es el segundo renglón más importante en la producción agrícola después del café, 55 % del total del área cultivada se dedica a la producción de panela (Azúcar no centrifugado-NCS, por sus siglas en inglés) labor que se realiza en 29 de los 32 departamentos del país. Los bajos rendimientos y la pérdida de calidad genética de los materiales que actualmente se cultivan ha traído consigo la necesidad de evaluar nuevas variedades de caña de azúcar que se adapten a diversos ambientes y que cuenten con una alta producción de panela. Teniendo en cuenta lo anterior, entre noviembre de 2018 y mayo de 2020, por parte de la Corporación Colombiana de Investigación Agropecuaria – Agrosavia, bajo las condiciones agroecológicas de Barbosa (Santander, Colombia), se evaluó el comportamiento agroindustrial de seis variedades de caña de azúcar para producción de panela (CC 11-600, CC 10-450, CC 99-2461, CC 00-3257, CC 91-1606 y CC 00-3771) provenientes del centro de investigación de la caña de azúcar de Colombia – Cenicaña; se estableció un diseño de bloques completos al azar con cuatro repeticiones para el comportamiento agronómico y tres repeticiones para la evaluación industrial. En lo agronómico, los materiales genéticos presentaron promedios de 2,81 m para altura de tallo a punto de quiebre, 2,8 cm de diámetro de tallo, porcentaje de intensidad de infestación de Diatraea del 10,66% y 118,92 toneladas de caña por hectárea; para las variables industriales, sen encontraron valores promedio de 21,06 °Brix en jugo y 12,78 toneladas de panela por hectárea, las variables evaluadas referentes a calidad de panela se ajustaron a las requeridas en las NTC 1311:2009 y Resolución 000779 de 2006 del Ministerio de Protección Social. Las variedades CC 11-600 y CC 00-3267 presentaron el mejor comportamiento agroindustrial en el primer ciclo productivo.