Ninety-five genotypes of Physalis spp. were evaluated in Morelos, Mexico, in order to find genotypes with genetic tolerance to the disease caused by Fusarium sp. It was evaluated the percent of disease plants four times (23, 36, 49 and 62 days after the trasplant) and the fruit yield. The statistics analysis consisted in variance analysis, means comparation and main components analysis. The genotypes 17GRO01, 48JAL08, 51JAL09, 58GRO06, 63JAL15, 77MEX04, 82MEX06, 85JAL24, 106MOR02 and SJ/27(1) were the most tolerant to Fusarium sp.; 94, 57, 61, 92, 93 and 30 genotypes were resistant to the disease, with good yield and big fruits (genotypes desirable for breeding programs); 77MEX04, 82MEX06, 58GRO06, 106MOR02 and SJ/27(1) genotypes were the most productive, while 77MEX04, 82MEX06 and SJ/27(1) were the most tolerant to Fusarium sp.

The cherimoya (Annona cherimolla Mill.) is a subtropical fruit that is very susceptible to physiological disorders during refrigeration. To determine the origin of some of these abnormal manifestations, fruits of cherimoya cv. Concha Lisa were harvested in the loca-tion of Quillota, Chile. The harvest index was the epidermal change of color. The fruits were stored for 42 days in cold storage at 5 °C with 90% relative humidity to accelerate any possible manifestation of the disorders. During storage, the fruit was evaluated every seven days. Physical and chemical parameters were evaluated such as soluble solids, acidity, epidermal color and loss of hu-midity. Once the disorders appeared, a histological and descriptive analysis of them was done. It was relevant that the disorders denominated pitting, spot and epidermal browning resulted from storage and each one caused a particular damage to the fruit. Epi-dermal browning is an advanced stage of the spots, but not of pitting.

Nine treatments of fertilization with nitrogen (76 to 150 kg⋅ha-1) and boron (0 to 8 kg⋅ha-1) were evaluated. The levels and treatments used were obtained by the experimental matrix Plan Puebla III. This research was carried out in Villa Emiliano Zapata, Veracruz, Mexico during 1989. There were no differences between plant height, diameter and number of fruits, and plant production. There were significant differences for the damage by papaw ringspot virus, with lower damage with the application of 129.4 kg⋅ha-1 of N and 8 kg⋅ha-1 of B.

Seasonal carbohydrate variation was evaluated in leaves and inflorescences of the ‘Colín V-33’ avocado at Coatepec Harinas, México. The aim of this work was to determine if this variation affects the retention of avocado flowers and fruits. The content of reducing and total sugars and starch, and specific weight were determined for leaves (north and south sides of the canopy). Soluble sugars were determined in the inflorescences (apical and basal parts) in autumn and winter. Carbohydrates in the leaves varied in relation to the main phenological stages and leaf age. In September the highest content of sugars and starch was registred. During the autumn and winter the carbohydrate content in blossoms was lower. Reducing sugars were 28% higher in leaves of the south side. Specific weight showed almost no change in relation to phenology, but it varied with leaf age. Inflorescences showed more sugar content than leaves, and their apical part had higher total sugar content. The autumn inflorescences showed higher total sugar content, while the winter inflorescences had 50% more reducing sugars.

The effect of reduction in 75, 50 and 25% of major nutrients (N, P, K, Ca, Mg, S) in standard concentration of nutrient solution was evaluated during growth and development of chrysanthemum (Dendranthema x grandiflorum) in an open hydroponic system. In general: stem diameter; leaf area; leaf, stem and total plant fresh and dry weight was not significativily diminished by concentration reduction in 50% of major nutrients, but concentration reduction of 75% (25% of M) affected the most of the characteristics. However, the characteristic of flower quality (flower diameter, fresh and dry weight) were not affected, even stem length and flower life were greater and presented negative correlation with tissue nutrient content, especially N and K which never dropped into a deficient range.

In the present work a dialelic mating design with ten varieties of different husk tomato (Physalis ixocarpa Brot.) races was made. The objectives were to study the magnitude of the heterosis between varieties, to define the heterotic pattern, and the relative importance of additive and non additive effects. Dialelic crosses were made in the fall of 1994 and 1995, and they were evaluated in two loca-tions during the spring-summer cycle of 1996. From the ten studied varieties nine of them were self-incompatibles and the other one was self-fertile; however, the self-fertile variety did not produce fertile descendants when it was crossed with the others, but those crosses induced parthenocarpy. This phenomenon was also observed in the self-incompatible varieties when they were self-pollinated. Maternal and reciprocal effects were not significant; therefore, the inheritance of average fruit weight (AFW), fruits number per plant (FNP) and total yield per plant (TYP) traits was basically nuclear. The general combining ability effects were significant in the three studied traits and the specific combining ability effects were significant just in AFW; therefore, in FNP and TYP the additive affects were more important than the non additive ones. The average heterosis of the intervarietal hybrids was significant in the three studied traits (AFW = - 5.73 , FNP = 10.42 y TYP = 17.19 %). The hybrid between the Verde Puebla and CHF1-Chapingo varieties presented more TYP (14.29 %) than the best variety and its specific heterosis effect was more important than the varietal heterosis effect, in the three.

In order to explore the sucess in obtaining haploid plants, which once duplicated the chromosome number they can be used in plant breeding, a basic methodology was estabished for in vitro anther culture of husk tomato. Murashige and Skoog (1962) (MS), Chu (1981) (N6) and Nitsch and Nitsch (11969) (NN) solid media; two kinds of agar (agar-agar "Merck" and Gelgro "ICN"); 1, 3, 6, 12 and 15% sucrose and different cytokinin (kinetin and benziladenine) and auxin (indolacetic acid and 2,4- dichlorofenoxiacetic acid) combinations were tested. Plantlets were obtained within six weeks of culture on N6 medium supplemented by vitamins, 100 mg⋅litro-1 myoinositol, 3% of sucrose, 0.4% of Gelgro and 0.06 mg⋅litro-1 of indolacetic acid. The anthers gave rise to plantlets in 7.6% and they were diploid (2n=24) and mixoploid (n=12, 2n=24, 3n=36 and 4n=48).

Husk tomato is an important horticultural crop in Mexico. One of the goals of the husk tomato breeding program of the Departa-mento de Fitotecnia of the Universidad Autonoma Chapingo is to obtain husk tomato hybrids. However, the gametophytic self-incompatibility of husk tomato makes difficult to form hybrids. Anther culture is an option that needs to have the in vitro propagation method of husk tomato diploidized haploids. Therefore, the objetive of this research was to develop the in vitro propagation method for the varieties Rendidora, Salamanca and Tamazula. The explants were sections of stem, leaves, petioles and axilar buds. The media was Murashige and Skoog (1962) (MS) supplemented with 2, 4-diclorophenoxiacetic acid (2,4-D), naphtalenacetic acid (NAA), benziladenine (BA) and indolacetic acid (IAA). ‘Rendidora’ formed callus in stems and leaves. The best treatment was BA 10 mg⋅liter-1 and IAA 3.0 mg⋅liter -1. In ‘Salamanca’ the best treatment was 2,4-D 1.0 mg⋅liter-1. In ‘Tamazula’ the best treatments were NAA 0.1 mg⋅liter-1 and 2,4-D 3.0 mg⋅liter -1. In relation with the formation of adventitious shoots the best treatments for ‘Rendidora’ were BA 3.0 mg⋅liter -1 and IAA 0.1 mg⋅liter -1. In ‘Salamanca’ the best treatment was BA 3.0 mg⋅liter-1 and for ‘Tamazula’ BA 1.0 mg⋅liter -1. The rooting of adventitious shoots in the three varieties was achieved using 75% of the inorganic salts of MS without growth regulators.

The main objective of this study was to determine the inflorescence traits that could have been modified by the process of domestication in Tagetes erecta. To this purpose, artifitial depth soil conditions were designed and domesticated and wild T. erecta germplasm were included to detect the main floral structure changes. T. erecta ssp. cultivated and both T. erecta ssp. huetamo and T. erecta ssp. tlalámac wild plants were grown in pots with 3 kg of soil and containers with 30 g of soil. Wild genotypes grown under different soil environments showed few changes on size and number of floral traits, in the other hand, changes of floral traits in domesticated genotype were profuse, particularly the involucre width and the number of flower per inflorescence. Considering to T. erecta ssp. huetamo as the putative parent of T. erecta ssp. cultivated, the last one had significant increases in several floral traits: like involucre width and length, number of flowers per capitulum and the number of ligules, and reduction in seed size.

In 1993, 35 amaranth selections were cultivated under two conditions of rainfall and after evaluated in laboratory for their capacity of grain bursting with a heated surface. The results indicated that, a high amount of burst grain (pop grain) was associated with few rain during reproductive growth period (RGP) of the amaranth, although the grain yield was low in the same conditions. In general, the grain harvested in conditions with few rain during RGP, increased its volume more than the grain obtained in regions with more rain in the same period.