Cytology and mating systems in the climbing cacti Hylocereus and Selenicereus

Chromosome numbers and meiotic behavior are reported for the climbing cacti species Hylocereus undatus, Hylocereus polyrhizus, and Selenicereus megalanthus. The Hylocereus spp. are diploid (2n 5 22), while S. megalanthus is a tetraploid (2n 5 44). Irregular chromosome disjunction at anaphase I in pollen mother cells of S. megalanthus is probably the major cause of its reduced pollen viability and may contribute to low seed set, low number of viable seeds and, consequently, low fruit mass. A pollination study confirmed self-incompatibility in H. polyrhizus and a weakened incompatibility reaction in H. undatus and S. megalanthus. Major crossability barriers do not exist between the Hylocereus spp. investigated. Reciprocal intergeneric crosses were successful between Hylocereus spp. and S. megalanthus, suggesting that an Hylocereus sp. Might be one of the diploid progenitors of the tetraploid S. megalanthus. The implications of the results on cacti nomenclature and systematics are briefly discussed

Identifying non-destructive growth and maturity indexes of Prickly pear (Opuntia albicarpa S. Var. Burrona) and evaluation of freeze-drying conditions

Around the world, prickly pear fruits are valued as a source of dietary functional compounds and ingredients for innovative foods. Growth and physicochemical changes of Opuntia albicarpa S. fruits were recorded from 0 to 132 days-after-flowering (DAF) to identify non-destructive maturity-indices. Optimum-ripened fruits were freeze-dried to study physicochemical and functional characteristics of dried and rehydrated pulp. Principal component analysis confirmed growth turned into fruit ripening in DAF 99, and it lasted until DAF 132. Changes in color parameters of the peel correlated with fruit texture and pulp sugar content and taste index (P < 0.01). During freeze-drying, plate temperature had more significant effects than the thickness (P < 0.05). At 30°C, color ΔE between dried and fresh slices augmented, but, texture Δ´s (medium force) between rehydrated and fresh pulp was lower. Color tests could be used to harvest commercially-ripened fruits. Freeze-drying at 30°C improves the rehydrated slices texture regarding thickness maintaining rehydration coefficients.Las tunas son apreciadas en todo el mundo como fuente de compuestos funcionales dietarios e ingredientes para alimentos innovadores. Para identificar índices de maduración no destructivos, se registraron cambios en el crecimiento y en los parámetros fisicoquímicos de frutos de Opuntia albicarpa S. entre los días después de la floración (DAF) 0 al 132. Frutos con maduración óptima fueron liofilizados para evaluar características fisicoquímicas y funcionales de pulpa seca y rehidratada. El análisis de componentes principales confirmo que el crecimiento dio lugar a la maduración en el DAF 99 y ésta prosiguió hasta el DAF 132. Los cambios en parámetros de color en cáscara correlacionaron con la textura del fruto, y en pulpa, con el contenido de azúcares y el índice de sabor (P< 0.01). Durante la liofilización, la temperatura de placa tiene más efectos significativos que el espesor (P≤ 0.05). A 30°C, el ΔE de color entre la pulpa seca y fresca aumentó, pero, el Δ de textura (fuerza media) fue menor entre la rehidratada y la fresca. Se pueden emplear evaluaciones de color para cosechar frutos en su madurez comercial, y liofilizar estos frutos a 30°C mejora la textura sin importar el espesor, manteniendo los coeficientes de rehidratación.This work was supported by the SIMORELOS program of CONACyT

Fenologia reprodutiva da pitaya vermelha em Jaboticabal, SP

The dragon fruit (Hylocereus undatus) is recent crop cultivation in Brazil and there is still lack of studies to support the farmers. So, this research aimed to characterize the reproductive phenology of the crop in the region of Jaboticabal, Sao Paulo State, Brazil. It was evaluated red dragon fruit clones over two environmental conditions - under plastic screen black and white, with 50% of shady level, from March 2009 to December 2010. It was observed that the issuance of floral buds and the flowering on dragon fruit culture occurs with a combination of high temperatures and rainfall, with constant emission of floral buds from November to March while the flowering on dragon fruit culture occurs until mid-April. The color of plastic screen had influenced on amount of flowers. The time elapsed since the issuance of flower buds to anthesis is from 18 to 23 days, while the harvest occurs from 34 to 43 days after flower opening. At Jaboticabal, the time of appearance of flower bud to fruit harvest is from 52 to 66 days.Por ser uma cultura de cultivo recente no país, a pitaya (Hylocereus undatus) ainda carece de estudos, de forma a dar suporte aos produtores. Nesse sentido, o trabalho foi desenvolvido visando a caracterizar a fenologia reprodutiva da cultura na região de Jaboticabal - SP. Avaliou-se clone de pitaya conduzido sob duas colorações de tela plástica, branca e preta, ambas com 50% de sombreamento, durante março de 2009 a dezembro de 2010. Observou-se que a emissão de gemas florais tem início no mês de novembro, com emissão constante até o mês de março, enquanto que o florescimento ocorre até meados de abril, sendo que as altas temperaturas associadas ao início da estação chuvosa são fatores fundamentais para a emissão das gemas reprodutivas. A coloração da tela plástica influenciou no total de flores. O tempo compreendido desde a emissão das gemas até a antese é de 18 a 23 dias, enquanto, da antese à colheita é de 34 a 43 dias. O tempo total entre o aparecimento do botão floral até a colheita pode levar de 52 a 66 diasAgencia Desenvolvimento Agr &Extensao Rural AGRA, BR-79114005 Campo Grande, MS, BrazilInst Ensino Super Ariquemes, Ariquemes, RO, BrazilUniv Estadual Paulista Julio Mesquita Filho UNESP, Fac Ciencias Agr &Vet Jaboticabal, Dept Prod Vegetal, Jaboticabal, SP, BrazilUniversidade Estadual Paulista Julio Mesquita Filho UNESP, Fac Ciencias Agr &Vet Jaboticabal, Departamento Produção Vegetal, Jaboticabal, SP, Brazi