Tomatillo (Physalis ixocarpa Brot. ex Horm.) is widely grown in Mexico with non-certified seed. Little research has been done on seed drying and physiology. Seed drying is a fundamental process in production technology, and the temperature used can affect its quality. This study aimed to evaluate the effect of different drying temperatures on the physical and physiological quality of seeds of four varieties (Tecozautla 04, Diamante, Gema and Manzano Tepetlixpa) in three storage periods. Seeds of each variety were dried in an oven until reaching constant weight at different temperatures: ambient, 30, 35, 40, 45, 50, 55 and 60 °C; subsequently, they were stored under ambient laboratory conditions for 0, 2 and 4 months. The experimental unit was 5 g of seeds. The study was carried out under a completely randomized experimental design with four replications. Physiological quality was evaluated with standard germination tests, and with the vigor test the germination speed index, total seedling length and seedling dry weight were determined. Seed quality was affected by temperature. When drying from 30 to 35 °C, the seeds expressed their maximum physiological quality, and above 45 °C their quality decreased. Tecozautla 04 had the greatest vigor, whereas Diamante had the least vigor and was the most sensitive to damage during the drying process. After two months of storage, the seeds showed the best physiological quality.

Avocado plant propagation in Colombia is done by grafting commercial materials, such as ‘Hass’, ‘Lorena’, ‘Choquette’, ‘Fuerte’, ‘Reed’, and ‘Trinidad’, among others, onto rootstocks produced from sexual seed from Creole and ‘Hass’ trees. These seeds can be obtained in local markets or in avocado-producing areas located in contrasting agroecological regions without well-defined selection criteria. This work aimed to characterize the morphological variability of 80 seed-donor avocado (Persea americana Mill.) trees for rootstock production in three producing areas of Colombia. Thirty-nine morphological descriptors were evaluated for characterization, including qualitative and quantitative characters of plants, leaves, fruits and seeds. Multiple factorial analysis detected high morphological variability in fruit and seed characteristics in the three avocado-producing zones, while cluster analysis allowed the identification of three fully formed groups, so it was not possible to discriminate groups of trees by area of origin. With the results obtained, it was possible to determine a wide phenotypic divergence in the analyzed seed-donor trees, where 80 % of them presented outstanding physical characteristics of seeds for rootstock production.

P lants raised in small cell trays are often subjected to root growth restrictions. Root tips are a source of cytokinin, and insufficient biosynthesis and transport of this hormone to the aerial part severely impairs shoot development. Exogenous supply of cytokinin to the foliage has been shown to effectively counteract these effects in several horticultural crops, but the physiological processes involved are still unclear. The aim of this work was to study the effect of spraying the cytokinin 6-benzylaminopurine (BAP) on growth and development of plug lettuce seedlings focusing on the morpho-physiological mechanisms involved in plant response. Two experiments were conducted in a greenhouse. Lettuce (Lactuca sativa L. Crimor INTA) seedlings were grown for 35 days in 128-, 200- and 288-cells trays (17.37, 13.90 and 6.18 cm³ ·cell^-1 respectively), after which they were sprayed with BAP (6-benzylaminopurine) solutions (0, 5, 50 or 100 mg·L^-1) either immediately before transplant, or 7 days after transplant. Seedlings were transplanted into larger (3,000 cm³ ) pots in which they grew for further 60 days. Decreasing plug cell volume resulted in a steep decrease in plant net assimilation rate and leaf net photosynthetic rate, but the impact on the relative growth rate was somewhat lower due to an increased leaf area ratio. BAP sprays increased plant biomass accumulation and enhanced the development of photosynthetic area, in parallel with a strong promotion of carbon assimilation, and these effects were more remarkable in plants raised in smaller plugs, and when hormone was supplied at the pre-transplant stage.