Vegetative propogation in abiu (Pouteria caimi

Abstract

Abiu [Pouteria caimito (Ruiz & Pavon.) Radlk.] is an exotic tropical fruit, originated from the Amazon region in Brazil. It belongs to the Sapotaceae family and is one of the upcoming novel fruits. The fruit is distinct due to its peculiar taste which is often compared to that of a mix of tender coconut, vanilla and custard. Due to their unique flavour and nutritional benefits, fruits of abiu are often sold at a premium price, providing higher income for the farmers. As the climate and soil conditions in Kerala are congenial for the cultivation of abiu, there is lot of scope for taking up the commercial cultivation of this crop in Kerala. So, in order to maintain their true to type character and to produce planting materials of identified superior types, vegetative propagation techniques have to be standardized. Under this context, the present study entitled “Vegetative propagation in abiu (Pouteria caimito)” was carried out in the Department of Fruit Science, College of Agriculture, Vellanikkara during the year 2023-2024 with the objective of standardizing an efficient vegetative method of propagation in this fruit crop. The research programme consisted of six experiments. In the first experiment, trials were conducted to enhance the seed germination and seedling growth parameters. The experiment was laid out in CRD with seven treatments replicated thrice with three seeds in each replication. The different seed treatments included control (T1), Acid scarification (T2), Hot water scarification (T3), Sandpaper scarification (T4), GA3 200 ppm (T5), 2% KNO3 (T6) and 2% Thiourea (T7). The seed treatment with GA3 (T7) took least number of days for germination while maximum number of days for germination was recorded in sandpaper scarification (T4) while seeds treated using hot water scarification (T3) did not germinate at all. The seedling growth parameters like seedling height, seedling girth and number of leaves was found to be maximum in GA3 (T5) which was on par with KNO3 (T6) and thiourea (T7). The second experiment on propagation by stem cuttings was laid out in CRD with two factors and was done during June 2024. The first factor was type of cuttings with three treatments viz., terminal cuttings (C1), softwood cuttings (C2), and hardwood cuttings (C3). The second factor was growth regulators with three treatments, IBA 4g/L (G1), IAA 4g/L (G2) and NAA 4g/L (G3). The treatments were replicated twice with six plants in each replication. Sprouting was observed only in hardwood cuttings in combination with all the three growth regulators but later got dried up and failed to survive further. The third experiment was propagation by air layering which was carried out during June 2023 and was laid out in CRD with four treatments replicated four times with six air layers per replication. Treatments were Coir pith compost (T1), Vermicompost (T2), Sphagnum moss (T3), and FYM (T4). Sphagnum moss (T3) was found to be superior in terms of number of days for root emergence, number of rooted layers, mean number and length of adventitious roots per air layer but after planting, complete mortality of all the air layers was recorded irrespective of treatments. The fourth, fifth and sixth experiments (propagation using softwood grafting, patch budding and approach grafting) was also laid out in CRD with six treatments replicated thrice with six plants in each replication. The different rootstocks taken as treatments were Abiu (T1), Eggfruit (T2), Sapota (T3), Khirni (T4), Star apple (T5) and Wild star apple (T6). In softwood grafting, abiu as the rootstock (T1) showed maximum values for scion growth parameters which was followed by sapota as the rootstock (T3) while remaining treatments failed to survive. In patch budding and approach grafting experiments, only the treatment using abiu as the rootstock (T1) resulted in successful sprouting and survival, whereas the other treatments failed to survive till the end of the experiment. Results from the present study indicated that stem cuttings, air layering and patch budding were not suitable for commercial propagation of abiu in the region of Kerala. Softwood grafting of abiu using abiu and sapota rootstocks exhibited significantly good result for scion growth parameters and survival, whereas in approach grafting, only abiu rootstock survived successfully. The study also showed that seed treatment with thiourea recorded early seed germination while pre-soaking treatments with GA3, thiourea and KNO3 positively influenced the seedling growth parameters. However, scarification treatments negatively influenced the germination and growth of abiu seedlings.