Citrus flowering is a complex phenological process influenced by a number of interacting factors. Low winter temperatures are recognized as an important factor, but the flowering response has not been quantified under Variable natural conditions. A study was conducted to monitor the flower bud induction response of `Valencia' and `Hamlin' sweet orange trees [Citrus sinensis (L.) Osbeck] to naturally occurring winter weather conditions during the 1999 and 2000 seasons. The flowering response was quantified and related to shoot age, bud position along the shoot, local weather information, and crop load status. Results indicate that buds on previous summer shoots developed 2.52 and 3.59 to 1 flower on spring shoots, for `Hamlin' and `Valencia', respectively. In addition, buds at apical positions produced more flowers than buds located far from the apex. These basal positions buds required higher induction levels. Under Florida conditions, greater accumulation of hours of temperatures 11 to 15 °C increased floral intensity by the combined effect on the number of sprouting buds with reproductive growth and the number of flowers per flowering bud. Some statistical analyses indicated that high winter temperatures reduced flowering in `Valencia' and `Hamlin' oranges. The presence of fruit consistently reduced reproductive response for both cultivars. Crop load reduced flowering by an average of 41.5% compared to no crop and varied by cultivar. A discussion on the different induction requirements as well as on the differential effect of crop load on flowering by cultivar is presented.
In Mexico, piquin peppers are highly valued horticultural products with limited cultivated production due to low seed germination, morphologic and genetic variability, disease susceptibility, and limited environmental physiology information. The objective of this study was to evaluate the effects of irrigation frequency and shade level treatments on vegetative growth, yield, and fruit quality of a commercial ecotype of piquin pepper. The study was conducted during two consecutive years using a hierarchical linear mixed-effects model design, with yearly data of irrigation frequency as main treatment blocks and shade levels as secondary blocks (nested within irrigation frequency treatments). Our results indicate that more frequent irrigation and increased shade levels favored vegetative growth. In addition, moderate shade levels (interception of 35% of full sunlight) and daily irrigation provided the best conditions for fruit production. This effect could be attributed to an increase in vegetative growth (thus higher photosynthetic and crop load capacity); more moderate conditions (temperatures and relative humidity) that favored flowering and fruit set, or a combination of these factors. Fruit size and pungency were not significantly affected by the treatments. Our results provide basic information for the development of guidelines for the cultivation of piquin pepper plants.
Fungal diseases have their greatest impact on citrus in Florida by reducing tree vigor, fruit yield, and quality. Given the complex etiology of these diseases, this software was developed to facilitate diagnosis of symptoms and to explain the dynamics of Alternaria brown spot of mandarins, greasy spot, melanose, Phytophthora brown rot, post-bloom fruit drop, and sour orange scab. CITPATH includes a diagnostic key to identify symptoms of the major fungal diseases of citrus foliage and fruit in Florida and a hypertext program containing a description and graphic display of symptoms, maps of geographic occurrence, diagrams of disease development, and management strategies. Users can also consult a list of citrus cultivars susceptible to specific diseases and a reciprocal list of diseases affecting specific cultivars. Chemical control methods are discussed briefly with reference to the current Florida Citrus Spray Guide, a hardcopy of which is included with the software purchase. Developed for commercial growers, county extension programs, citrus horticulture classes, and master gardeners, this software is available on CD-ROM disks containing other citrus databases and as a separate disk for MS-DOS-based computers.
CITPATH, a computerized diagnostic key and information system, was developed to identify the major fungal diseases of citrus foliage and fruit in Florida. This software provides hypertext-linked descriptions and graphic displays of symptoms, maps of geographic occurrence, diagrams of disease development, and management strategies, with reference to chemical control methods detailed in the current Florida Citrus Pest Management Guide. Reciprocal lists of citrus cultivars susceptible to specific diseases and diseases affecting specific cultivars are included. Developed for commercial growers, county extension programs, citrus horticulture classes, and master gardeners, this software is available for MS-DOS-based computers and on CD-ROM disks containing other citrus databases.
Although habanero peppers (Capsicum chinense, Jacq.) are highly appreciated as a result of their organoleptic and pungency properties, the crop faces edaphic stresses throughout Mexico. A study was conducted to determine how the photosynthetic parameters, vegetative growth, yield, and fruit quality of the plant change in response to suboptimal conditions in the substrate. Habanero plants were grown in an inert substrate (perlite) and exposed to increased salinity levels (4 and 7 dS·m−1) and reduced nitrogen and phosphorus conditions. Plants grown with a Hoagland-based solution were used as controls. High salinity conditions reduced the light-saturated photosynthetic rates (64% of the control) but did not compromise yield or fruit quality. This effect was possibly the result of the addition of Ca2+, which reduced salinity-induced calcium deficiency. Although comparable low nitrogen levels in previous studies were shown to cause a severe reduction in plant viability, in our study, low nitrogen reduced the light-saturated photosynthetic rates (47% of the control) and shoot:root ratio (67% of the control) but did not significantly affect yield or fruit quality. Low nitrogen and 7-dS·m−1 treatments increased fructose and glucose content (increases of 27% and 21%, respectively). Low phosphorus significantly affected plant growth and yield and reduced fructose content (73% of the control). Plants were not sensitive to low nitrogen and high salinity, possibly as a result of the use of nitrate-based fertilizers and the addition of calcium, respectively. These results provide guidelines for habanero pepper production under suboptimal edaphic conditions.