Successful grafting elite cocoa clones (Theobroma cacao L.) as a function of the age of rootstock
Description
Agromorphological data of cocoa clones grafted at different rootstock ages in nursery.
Files
Steps to reproduce
The methodology used to obtain our results data is as follow. Planting material was composed of the 10 cocoa clones used in the revitalization program of the cocoa sector in Côte d'Ivoire coded as C1, C8, C9, C14, C15, C16, C17, C18, C20, and C21. To produce the rootstocks (made up of cocoa clones’ seedlings), the polyethylene bags were filled with a substrate composed of 1/3 compost, 1/3 Arabic soil, and 1/3 sand. Pre-germinated cocoa beans were sown in these filled bags. Fungicides (Ridomil Gold66WP) and insecticides (Banko plus) were applied fortnightly to the seedlings in order to ensure protection against the attacks of fungi and insects. Manual weeding was undertaken every two weeks to avoid competition between the rootstocks and weeds. At grafting stage, young seedlings of homogeneous size were selected to serve as rootstocks. Rootstocks were raised for two, three, and four months in the shade house. Healthy scions of each clone that had no visible signs of disease or pests according to visual observations were collected randomly from actively growing trees the day before each grafting operation. These scions were stored in fresh banana leaves and placed in a humid place to ensure their viability. The branches were cut into 2, 3 or even 4 depending on their size, so that each of the pieces had at least two buds or even four as recommended by Munjuga et al. (2013). Each budstick was enveloped in parafilm, a biodegradable material that keeps the graft from drying out to avoid breaking the emerging buds. This grafting consisted of transversely sectioning the rootstock with a shears and thereafter posing a slit with the help of a graft. The graft was beveled and inserted into the slit, then all ligated using a transparent plastic film. Experimental design was a RCBD with three replications. The 10 cocoa clones were grafted at the 3 ages of the rootstock including 2, 3, and 4 months. The experimental unit consisted of five grafted seedlings for each age of rootstock and each clone replicated three times giving a total of 450 seedlings for the entire experiment. The morphological characteristics of the clones were evaluated ten days and then one month after grafting and consisted in the measurement of the number of emerged shoot and the height of seedlings. At one month after grafting, the number of branches, the length of the main branch, the diameter of the main branch, the number of leaves, the number of internodes of the main branch, and the height of the plant were determined. The grafting success rate was determined as the proportion of individuals having retained at least one emerged shoot leading to a branch. This rate was determined as follows: Success rate = Number of successful grafts x 100/total number of rootstocks. Data collected were subjected to two-way analysis of variance, using the general linear model of Statistical Analysis System software version 9.2 (SAS, 2003), and Duncan's test at 5% was used to separate the means.