The Minolta chlorophyll meter SPAD-502 (Minolta Camera Company, 101 Williams Drive, NJ 07446, USA) was evaluated as an accurate, nondestructive means to measure chlorophyll content in citrus leaves. Meter readings from leaves of sweet orange and grapefruit citrus cultivars were used to develop a standard curve for citrus. A significant correlation value of 0.96 was calculated between the chlorophyll meter readings and actual chlorophyll extraction levels. The development of a standard curve using the SPAD-502 chlorophyll meter had not been established on citrus. The SPAD-502 chlorophyll meter proved to be a quick, accurate, simple, and nondestructive way to determine chlorophyll content in citrus leaves.
Robert E. Rouse, Sandra P. Perez, and Sally B. Davenport
J.A. Franco, P.J. Pérez-Saura, and A. Durán
The appearance of blossom-end rot (BER) in tomato is related to a decrease in the absorption and translocation of Ca due to excessive salinity in the soil solution. An experiment was conducted to investigate the effects of calcium nitrate (NT), EDTA-Ca (ED) and Aminoquelant-Ca (AQ)—a product containing Ca, B and protein hydrolisate—on the yield and incidence of BER when applied to the leaves of tomato (Lycopersicon esculentum Mill. `Durinta') grown in the open with a drip irrigation using saline water from a well (mean ECw 5.2 dS·m–1). The three calcium treatments and control were replicated four times, with 12 plants per replication, in a completely randomized design. Although yield per plant was higher with AQ, the difference was not statistically significant. Fewer fruit were affected by BER after treatment with ED and AQ than with NT and in the control. Leaf Ca concentration did not differ significantly between treatments. However, leaf B concentration was higher after treatment with AQ. Fruit Ca and B concentrations did not differ significantly in any treatment. The total free amino acids content in leaves was higher after AQ treatment than in the other treatments and control, although no significant difference was observed between the treatments in the fruit.
M.E. Pérez de Camacaro, G.J. Camacaro, P. Hadley, N.H. Battey, and J.G. Carew
The differences in growth and yield in the Junebearing strawberry (Fragaria ×ananassa Duch.) `Elsanta' and the everbearing `Bolero' and `Everest' were evaluated under field conditions. The seasonal patterns of radiation use efficiency and assimilate partitioning were also studied. Growth, development and yield showed considerable differences among cultivars. `Elsanta' showed the highest and `Bolero' and `Everest' the lowest values for almost all the vegetative parameters (leaf area, leaf dry weight, runner number). `Elsanta' produced large leaves and few crowns per plant in contrast to the everbearing cultivars which had more but smaller leaves and a larger number of crowns per plant. The production of flowers by `Elsanta' was concentrated in June with fruit production following in July. `Bolero' and `Everest' produced more than one flush of flowers during the season and fruited until October. As a result, yields of `Bolero' and `Everest' were greater than `Elsanta'. The higher yields of `Bolero' and `Everest' also reflected the greater number of crowns produced by these cultivars. The maximum intercepted and absorbed photosynthetically active radiation (PAR) occurred between July and August when the three cultivars showed the greatest increase in vegetative growth. Harvest index clearly differed among cultivars and this was related to the duration of cropping. The greatest harvest indexes were found for `Bolero' and `Everest'.
C. Avilla, J.L. Collar, M. Duque, P. Pérez, and A. Fereres
Laura P. Peña-Yam, Liliana S. Muñoz-Ramírez, Susana A. Avilés-Viñas, Adriana Canto-Flick, Jacobo Pérez-Pastrana, Adolfo Guzmán-Antonio, Nancy Santana-Buzzy, Erick A. Aguilera-Cauich, and Javier O. Mijangos-Cortés
The variability and genetic parameters of seven agronomic characteristics were estimated for 11 genotypes, and high values of the phenotypic coefficient of variation (PCV) of capsaicin content (CC) were obtained. Heritability (h2) was high for yield per plant (YP; 0.98) and CC (0.93). The principal components analysis (PCA) revealed that the first three components explained 94.02% of the total variation; therefore, genotypes with higher YP values and fruit weight (FW) (AKN-08, ASBC-09) were placed in quadrant I. Those with greater CC and lowest YP and FW (MBI-11, RES-05) were placed in quadrant II. The greatest fruit length (RNJ-04) was placed in quadrant III. Those with the greatest number of fruits per plant (NBA-06, RKI-01, RHC-02, RHN-03, NKA-07, and MSB-12) were placed in quadrant IV. The results showed that the genotypes studied comprise an excellent source of genetic material for Habanero pepper improvement programs.