Starfruit (Averrhoa carambola L.) is reproduced by seeds from `Criollo' cultivars. The replication of desirable agronomic traits is difficult when selected plants are from sexual reproduction. The heterogeneity of plants is observed as higher trees, irregular fresh fruit yield, variable fruit quality, differential insect pest and disease susceptibilities, and extended period for recovering the inversion. Vegetative propagation is an alternative for reducing the heterogeneity of starfruit trees. Four grafting methods for propagating starfruit in the coast of Colima, Mexico: splice-side graft, wedge graft, whip graft, and bud graft were evaluated. The experiment was carried out on the Tecoman campus of the Universidad de Colima. The ambient conditions were dry tropic (BS1). Seven-month-old rootstocks were obtained from Criollo seedlings, and the scion was obtained from a healthy 15-year-old `Miss' donor tree. The experiment was distributed under a completely randomized design. The splice-side graft had 70% success and was the best, bud graft had 40% success, wedge graft, had 5% success and whip graft 0% success, and was the least successful.
Juan Manuel González-González, Salvador Guzmán-González, and Sergio Chavez-Luna
Juan Manuel Gonzalez-Gonzalez, Salvador Guzman-Gonzalez, and Jorge Medina-Grijalva
We evaluated the effect of five doses (0, 500, 1000, 5000, and 10,000 ppm) of indole butyric acid (IBA) on the aerial layer induction root of Litchi (Litchi chinensis Sonn.). The experiment was conducted in the coastal zone of Tecoman, Colima, Mexico, at the La Perla farm (18°15'N; 103°52'W and 33 m above sea level). The ambient conditions were dry tropics with an average yearly rainfall of 710 mm and 26 °C annual medium temperature (BS1). The evaluated variables were: 1) the number of roots emitted by layer, and 2) percentage of layers taken root by treatment. The experiment was carried out under a randomized block arrangement. We used five treatments with 12 repetitions, considering one tree to be a block, in which five treatments were effected with four repetitions into every one tree utilized. Results of Duncan's test averaged 5%. The results obtained indicated that dose of 500 ppm was the best IBA level as the percentage of layers taken root by treatment (96.7%). They are statistically different.
Javier Farias-Larios, Mario Orozco-Santos, and Salvador Guzman-Gonzalez
Muskmelon (Cucumis melo L.) is the major cucurbit crop in the Colima state, Mexico. The use transparent plastic mulch continues to increase in that region for high production technology systems of muskmelon, and more recently floating rowcovers were introduced to protect cucurbits from insects (direct pests or vector of viruses) and to increase yield of cucurbit crops. During 1993, yield was evaluated of three cultivars of muskmelon (`Crushier', `Laguna', and `Durango') growing on transparent polyethylene mulch alone or with floating rowcover. The cultivar Crushier showed the higher yield 40 ton/ha (77% for export market), followed by `Durango' with 28.5 ton (77% for export quality) and `Laguna' with about 23 ton (only 40% of export fruit). There was no significant difference in yield between cultivar growth on transparent mulch plots alone and combined with floating rowcover. Also, floating rowcover excluded (until perfect flowering) beetles leafminers, sweetpotato whitefly, and aphids, reducing the use of insecticide by 50%.
Marcelino Bazan Tene, Juan Manuel González Gonzalez, Francisco Radillo Juarez, Jorge Pahul Covarrubias Corner, and Salvador Guzman Gonzalez
The hot pepper (Capsicum annuum L.) is a plant domesticated in Mesoamerica. Hot pepper is currently widespread worldwide, and its uses are varied, such as for flavoring, pigment base, and as a nutritional food resource. Mexico produces about 623,238 tons/year of fresh fruits in 136,398 ha; the State of Colima produced 17,181 tons in 676 ha, with a mean of 27 t·ha-1. The culture of hot pepper in Colima faces certain limitations to its productive potential, such as lack of fertile and well-drained soils, constant soil moisture, and being free of weeds during the first weeks after transplanting; and maintaining plant uniformity in transplantation. This last practice is carried out in the side bed, but there is a lack of scientific evidence about the requirements of luminosity in the seed nursery in order to accelerate improvement of plant quality for transplanting, and the impact on fruit yield. The aim of this study was to evaluate the effect of different levels of shading on germination and vegetative development of `Jalapeño' hot pepper under greenhouse conditions. Four levels of luminosity were evaluated using mesh fabrics in order to produce 90%, 75%, and 50% shade, and control (0%) without shading on the seed beds. A completely randomized design with four treatments and four replications was used. The shading treatments reduced the germination period in about 2 days; increased the percentage of germination with a range between 1.6% and 3.7%; increased the plant height 2.3, 4.8, 7.72, and 10.1 cm at 3, 7, 13, and 18 days postemergence; increased the root biomass about 7.1 g/plant, and 5.4 g of fresh foliage with the 90% shade treatment in comparison with control. Overall, a better agronomic performance of the `Jalapeño' hot pepper was obtained with 90% shading.
Juan Manuel González Gonzalez, Salvador Guzman Gonzalez, Arnoldo Michel Rosales, Francisco Radillo Juarez, Marcelino Bazan Tene, and Fernando Cervantes T.
The most common spread of this species is sexual or by seed. In normal conditions, the germination of the seeds of Anonaceae can increase with pregerminative treatments prior to sowing. The objective was to determine the best pregerminative treatment to increase germination of soursop seeds. This study was carried out under the the dry, tropic conditions of Tecomán, Colima, Mexico. The experimental design was completely random with 12 treatments: 1) dip in water for 24 hours; 2) dip in water for 24 hours + gibberellic acid (GA3) at 350 ppm; 3) dip in water for 24 hours + GA3 at 500 ppm; 4) dip in water for 24 hours + GA3 at 1000 ppm; 5) mechanical scarification; 6) dip in water for 24 hours + mechanical scarification; 7) mechanical scarification + GA3 at 350 ppm; 8) mechanical scarification + GA3 at 500 ppm; 9) mechanical scarification + GA3 at 1000 ppm; 10) GA3 at 350 ppm; 11) GA3 at 500 ppm; and 12) GA3 at 1000 ppm; and control. There were four repetitions with 10 seeds in each experimental unit. The evaluated variables were the percentage of germination and the number of days from planting to emergence. To record results, analysis of variance and Tukey's test averages were used. The major percentage of germination resulted from the seeds treated with soaking in water for 24 hours plus GA3 to 350 ppm, dip in water for 24 hours plus scarification and GA3 at 1000 ppm, and equalized statistically to the control. For the number of days from planting to emergence, the treatment with mechanical scarification + GA3 at 500 ppm was statistically better. The use of gibberellic acid with mechanical scarification diminishes the dormancy of soursop seeds, producing plants in a relatively short period.
Salvador Guzmán-González, Pedro Valadez-Ramírez, Rosa-Edith Robles-Berber, Laura Silva-Rosales, and José-Luis Cabrera-Ponce
Biolistic genetic transformation of plants with viral genes is a method for controlling plant virus diseases; however, optimization of the particle bombardment parameters according to the transformation system is a key factor for an appropiate transgene expression and, therefore, a stronger resistance mechanism in transgenic plants. In order to optimize biolistic parameters, somatic papaya (Carica papaya L.) cv. Maradol embryo masses were bombarded with the CAMBIA 1301 plasmid construction that contains the coat protein gene (CP) of the papaya ringspot virus isolate of Colima, Mexico, driven by the double constitutively CaMV 35S promoter and flanked for the GUS and hygromycin (hpt) resistance genes. Particle bombardment protocol was carried out using the Helios™ Gene Gun device (BioRad) and the manufacturer's instruction manual. Helium pressure (50, 100, and 150 psi) and gold particle size (0.6, 1.0, and 1.6 μm) were evaluated. Five days after bombardment, somatic embryo clusters were used for GUS transient expression and, during 2 months, were selected into 50, 75, and 150 mg·L-1 hygromycin-containing media to its later CP-PCR detection. Results showed that 50 psi and 1.0 μm were the two optimal values for the assayed analyses. This is the first report of genetic transformation of papaya using the Helios™ Gene Gun device as a new tool compared to conventional PDS-1000/He.