Comparative ecology on the production of two clones from grafted dwarf cashew plants under irrigation conditions

The main aim of this research was to compare the production ecology between clones CP 076 and 1001 from dwarf cashew plants under localized irrigation conditions. This work was carried out from April 1985 to March 1991 at an experimental area of the Federal University of Ceara, in Caucaia, Ceara, Brazil. Observations were made on 10 grafted plants from each clone, which belonged to a clonal germoplasm spaced 6 m x 6 m. Averages concerning temperature, relative humidity of air, and wind speed, and monthly totals concerning insolation, solar radiation, and rainfall were measured during the whole experiment. Monthly and annual evolution of nut and peduncle productivities, nut number per plant, and nut and peduncle average weight were also evaluated. Variance analysis of all plant variables, and monthly and annual nut and peduncle correlations to the climate components were determined. Both clones concentrate their production during eight months a year, period in which rainfall and relative humidity of air are lower, although clone CP 076 was more uniform and continuous than clone 1001, which is produced intensively in a different period of the year and alternately. With exception of the 1985/86 period, a well-characterized negative correlation between the percentage of plant in production of clone CP 1001 and precipitation was detected. It was also observed a negative correlation between the percentage of plant in production of both clones and the relative humidity of air through the whole experiment. A variance analysis for both clones showed no significant statistical difference between their peduncle average productivities, but it showed a significant statistical difference between their nut average productivities in the sixth year of the experiment. A significant statistical difference between nut numbers for both clones was noticed in the second and in the sixth year. Besides that, no significant statistical difference between their annual average nut weight was detected in the first and sixth year of the experiment. Peduncle average weight of clone CP 076 was significantly higher than that of clone CP 1001 from the second through the fifth year of the experiment.