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Abstract
Virus-free plants of 8 monoembryonic cultivars of Citrus Clementina Hort ex Tan. were obtained by somatic embryogenesis of the nucellus cultured in vitro. Twenty-nine percent of them had abnormal phenotypic characters that were maintained for 7 years in the greenhouse, and by bud wood propagation on different rootstocks. Electrophoretic studies of the proteins disclosed differences in band intensity and distribution between normal and abnormal plants, indicating the possibility of genotypic variations. Alternative methods to obtain virus-free citrus plants are advised to reduce the high percentage of abnormalities.
Abstract
From experiments conducted over several seasons it was found that naringin production in grapefruit takes place mainly during the early stages of fruit development. In the most definitive study, developing grapefruit and adjacent leaves were exposed to 14C labeled carbon dioxide at weekly intervals following fruit set. The relative amount of CO2 fixed and available for conversion at different treatment times was determined by measuring the 14C activity in the soluble carbohydrate and organic acid fraction of the fruit. Activity was also followed in the naringenin rhamnoglucoside fraction. Carbon dioxide incorporation into the sugar-acids did not vary by greater than a factor of 10 for those exposures conducted from early April to mid-November. The ratio of activity in the naringenin rhamnoglucoside fraction to that in the sugar-acid fraction reached a pronounced maximum in mid-April and then declined rapidly by mid-June to 1/3000 of the peak value. A uniformly low ratio of incorporation into the naringenin rhamnoglucoside fraction is maintained to early maturity (October). Preliminary evidence suggests that minor subsequent rises in naringin production may coincide with periods of rapid vegetative growth.
Since 1980, farmers from western Mexico have cultivated melon cantaloupe; however, during the past few years, they have seen the better advantages of honeydew melon. Some of them represent a good alternative to farmers because chemical products and labor costs are reduced, and because they are tolerant to several diseases. The purpose of this experiment was to evaluate 15 new hybrids of honeydew melon in western Mexico. The hybrids evaluated were: Dey Break, Hmx 4596, Hmx 4595, Hmx 4607, Sunex 7051, Rocio, creme de menthe, Silver world, Emerald sweet, Sme 5303, Sme 5302, Santa Fé, PSR 10994, and PSR 8994, Honey Brew was test. Fifteen -day-old plants were transplanted by hand. Treatments were replicated four times in a randomized complete-block design. Beds 1.2 m wide and 7.0 m long were prepared, 1.5 m between beds, distance plant-plant 0.5 m (plant density ≈13,332 plant/ha). Results show that yield of SME 5302, SME 5303, HMX 4596, Rocío, Dey Break, PSR 8994, Sunex 7051, and HMX 4607 had a yield higher of 50 t/ha, Emerad sweet had more number fruit (59 per 10 plants), whereas SME 5303, SME 5302 and Silver world had higher fruit weight (>1.719 gr). We suggest the evaluation of these hybrids in other regions to know the adaptation to different conditions and to select the best in commercial quality and production.
Caborca, Sonora, is the principal raisin producer area in Mexico. It is estimated that over one-third of the fresh grape production is destined for raisins. There are no studies related to the insects that attack raisins in the fields during drying or in the processing plants where the raisins are stored for several months. The purpose of this study was to identify the insect pests and quantify the extent of the damage. Raisin samples were taken from the fields during drying and from the processing plants. The most abundant and frequent species identified were Oryzaephilus surinamensis L., Lasioderma serricorne Fab., and Cryptolestes pusillus Shoen. Also, Tribolium castaneum Herbst, Alphitobius diaperinus Panzer, and Rhyzoperta dominica Fab were less abundant and had a lower frequency. All these species were found in raisins stored in processing plants and none were observed in the field samples. Damage range was from 25 to 100% and was related to the length of time in storage. The longer the storage time, the higher the percent damage.
Vegetables are important in Mexican agriculture because of the exportation opportunities made available by the opening of the Free Trade Agreement. Okra represents a potentially profitable crop, and it is important to understand its behavior in a predetermined environment, and determine its optimal sowing density. The present work was realized to evaluate three genotypes and three densities of okra plants in the production and quality of fresh fruit. The work was realized in the winter–spring cycle in the dry tropic region, using a randomized block design with a bifactorial of nine treatments. During the cultivation cycle, the vegetative and productive variables did not present changes in phenology, and only registered differences in plant height (58.4 and 57.6 cm., respectively) of PX 416543 and `Green Best', with a distance between plants of 18 cm. These results indicate that with increased densities of 41,600, 50,000, and 69,444 plants/ha, there were no differences in the number and weight of fresh fruit/plant. Nevertheless, with the production and support the quality of fresh fruit increased. We conclude that high densities of plants increase the total crop of fresh fruit per hectare without affecting quality. The variety PX 416543 presented the best vegetative and productive behavior.
The total shell almond production in northwestern area in Mexico is ≈80 tons per year; therefore, almond fruit tree would be a potential fruit crop in this agricultural area. Also, this crop offers some advantages with lower costs than other fruit crop, and the water requirement needs for almond trees is low in support to the limited water availability. Our objective was to test new five almond cultivars of low chilling requirement. Almond cultivars were grafted on Nemaguard rootstock and planted during 1990. The data were collected from the almond orchard using the inshell kernel. The average yield during 1993 and 1994 were 970, 602, 552, 419, and 388 kg·ha–1 for `R-633', `Cavaliera', `Constantini', `Um El Fahm', and `Rane', respectively. `Cavaliera' and `Um El Fahm' showed good inshell percent and kernel weight. `Cavaliera' was harvested early in last week of June compared to the other cultivars that were harvested in mid-July.