Drought is the main limiting factor for maize production, and climate change can aggravate this water scarcity. One way to mitigate this problem is to plant drought tolerance maize genotypes. In landrace maize grown under rainfed conditions there are drought-adapted genotypes, which can be used in breeding programs for drought tolerance. The objective of this study was to evaluate the effect of an early water deficit on the seedling growth of 41 maize landraces from Nuevo León, Mexico, plus seven varieties, by means of drought tolerance indices based on biomass accumulation during both stress and post-stress recovery period, for identifying tolerant and susceptible genotypes. This study was performed at 2016 in Texcoco, Mexico (19°27’N, 98°54’W, 2241 masl). In the greenhouse, 96 treatments were compared (48 genotypes × two soil water regimes: without and with drought) under randomized complete blocks experimental design. After the drought stress period, normal irrigation was resumed for 15 days for recovery. In maize landraces there is genetic diversity in drought tolerance. Landraces GalTrini and SITexas outstanded as the most water deficit tolerant, whereas landraces Berrones, Rodeo, Sabanilla, Carmen, AraTrini and the inbred line L65 were the most drought susceptible. The total biomass measured before water stress was not related to drought adaptability. This study demonstrates that the post stress recovery is more important in drought stress adaptability than the drought resistance, regarding root biomass, shoot biomass and total biomass. Thus, to include the post stress recovery in drought tolerance studies can produce a more precise genotypic classification for drought stress resistance and adaptability.

Climate change has led to the search for strategies to acclimatize plants to various abiotic stressors to ensure the production and quality of crops of commercial interest. Sorghum is the fifth most important cereal crop, providing several uses including human food, animal feed, bioenergy, or industrial applications. The crop has an excellent adaptation potential to different types of abiotic stresses, such as drought, high salinity, and high temperatures. However, it is susceptible to low temperatures compared with other monocotyledonous species. Here, we have reviewed and discussed some of the research results and advances that focused on the physiological, metabolic, and molecular mechanisms that determine sorghum cold tolerance to improve our understanding of the nature of such trait. Questions and opportunities for a comprehensive approach to clarify sorghum cold tolerance or susceptibility are also discussed.

Physalis peruviana L. es originaria de los Andes y su fruto se consume fresco por su contenido de vitaminas y propiedades medicinales. El crecimiento de las plantas de esta especie es heterogéneo, pues tiene mejoramiento genético limitado porque es una especie silvestre. Los mutágenos físicos y químicos aplicados a semillas u órganos para propagación pueden generar variedades nuevas con cambios en morfología, rendimiento, adaptabilidad y resistencia. El objetivo de la presente investigación fue determinar el efecto de la irradiación de la semilla en los caracteres de la calidad del fruto de las plantas M1 de Physalis peruviana L., y se hipotetiza que al menos una dosis de la irradiación en plantas M1 de uchuva modifica favorablemente los caracteres de calidad de frutos. El estudio se realizó en invernadero con cubierta de plástico UVII-720, de agosto de 2015 a febrero de 2016. Los tratamientos fueron 14 dosis de rayos gamma 60Co (0 a 275 Gy) y el diseño experimental fue completamente al azar con seis repeticiones. La radiación redujo de 3 a 32% el peso del fruto con cáliz y de 3 a 29% el peso sin cáliz. La dulzura de los frutos se redujo con dosis mayores a 100 Gy, con excepción de 200 Gy; en contraste, la firmeza aumentó de 1 a 9% con las dosis de 100 y 75 Gy. El tamaño y vida de anaquel del fruto no se afectaron. La irradiación de semillas con rayos gamma 60Co altera negativamente el peso y algunas variables de la calidad del fruto de las plantas mutantes de P. peruviana.

<p><strong>Background. </strong>The husk tomato (<em>Physalis ixocarpa</em> Brot. ex Horm.) is an obligated allogam species with gametophyte auto-incompatibility, which impedes the generation of endogamic lines by auto-fecundation to obtain hybrids. <strong>Objective.</strong> To evaluate the effect of six doses of ⁶⁰Co gamma rays (from 0 to 300 Gy) applied to seeds, over seedling vigor, growth and reproductive features of M₁ plants of three husk tomato varieties (Manzano, Verde Puebla, and San Miguel). <strong>Methodology.</strong> The 18 treatments were distributed in a completely randomized design with five replications for the variables related to seedling vigor and 10 replications for the morphological and reproductive plant variables. <strong>Results.</strong> The radiation decreased emergency and survival of seedlings, height, and length of roots of M₁ seedling. Regarding the growth of M₁ plants, the doses of 100 and 300 Gy stimulated only height, the other doses had the same response as the control. Irradiation did not change self-incompatibility, as no fruit produced seed. <strong>Implications.</strong> The study allows to determine the sensitivity of the peel tomato to irradiation, by subjecting seeds to different doses of gamma rays and assess whether it is possible to obtain outstanding individuals in force and flowers that present self-fertilization, considering all the advantages of this type of pollination (form lines, to generate hybrids). <strong>Conclusions.</strong> The M₁ plants of the varieties Manzano and Verde Puebla excelled in growth; but those of San Miguel presented more self-pollinated flowers. The three varieties resulted sensitive to radiation; but growth variables varied depending on the variety and dose of radiation.<strong></strong></p>