Phenolic content and heritability of resistance in four hybrid populations of <i>Theobroma cacao</i> L. after leaves inoculation with <i>Phytophthora megakarya</i> Bras. et Grif

Abstract

Cocoa is cultivated in Cameroon for its broad beans. The commercialization of cocoa seeds constitutes a major source of income to farmers. Nevertheless, cacao black pod disease caused by Phytophthora megakarya is responsible of about 80% of cocoa production loss in Cameroon without any protection method. To assess the resistance of cocoa plants against this pathogen, necrotic lesions and phenolic content were conducted on 3 clones (SNK16, ICS40, Sca12) and their progenies (families F40, F12, F20 and F25) after leaves inoculation. The existence of strong hybrid vigour has been shown. All hybrid genotypes manifested a positive heterosis effect for this symptom suggesting the existence of hybrid vigour. Some hybrids like F40.

Breeding of parental and tolerant hybrids of Theobroma cacao L. to Phytophthora megakarya Bras. and Griff.

“…This could be due to genetic incompatibility between clones and also the period of pollination. This result is similar to those found by Mossu (1990) and Ondobo et al (2014).…”

“…This result is in agreement with the findings of Nyasse (1997). from the leaf disc test done in the laboratory, Efombagn et al (2011) on pods in field, Djocgoue et al (2010) and Ondobo et al (2014) on the leaves attached to the plant in nursery. There were significant (P<0.05) differences in the necrosis length of susceptible SCA 12 and SNK 16 as compared to T 79/501, T 79/467 and SNK 413.…”

“…The pathogenicity test was carried out in the nursery on leaves scarified along the midrib as described by Djocgoue et al (2006) and Ondobo et al (2014). The leaf test is an artificial inoculation method that can be used to assess the level of resistance in the genotypes.…”

Virulence Test of Some Phytophthora Megakarya Isolates on Cocoa (Theobroma Cacao L.) Hybrid Pods

“…However, the different responses of cocoa hybrids suggested that there could be an additive and dominant gene effect in the transmission of character [12] [21] [22] [23]. In the same way, a vast genetic variability for black pod resistance has also been reported in cocoa [9][14] [24].In our studies, the levels of tolerance of cocoa could be identified using any Phytophthora species. These findings are in agreement with results reported bysome authors [14][25] [26], who showed that the use of the most aggressive species of P. megakarya isolates could lead to the identification of useful levels of resistance against the pathogens.…”

Pengelompokan 33 Aksesi Kakao Berdasarkan Karakter Morfologi Komponen Buah

“…Beberapa karakter komponen buah kakao, yang meliputi ukuran buah (pod), biji, kulit buah, dan pulpa, berhubungan langsung dengan produktivitas tanaman serta ketahanan terhadap hama penggerek buah (PBK) (Susilo, Mangoendidjojo, Witjaksono, Sulistyowati, & Mawardi, 2009;Wijaya, Prawoto, & Ihromi, 2009;Asrul, Agus, Daryati, & Mollah, 2012;Limbongan, 2012;Pertiwi, Asrul, & Baja, 2013;Susilo, Mawardi, Witjaksono, & Mangoendidjojo, 2015) dan penyakit busuk buah Ondobo et al, 2014;Simo et al, 2014) .…”