Grafting as a strategy to increase flowering of cassava.

Leonardo Silva Souza,Reizaluamar De Jesus Neves,Alfredo Augusto Cunha Alves,Rafael Parreira Diniz,Eder Jorge De Oliveira

doi:10.1016/j.scienta.2018.06.070

Leonardo Silva Souza, Reizaluamar De Jesus Neves + Show 3 more

Open Access

https://doi.org/10.1016/j.scienta.2018.06.070

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Abstract

In cassava (Manihot esculenta Crantz), transferring genes via genetic breeding depends on crosses between contrasting progenitors, which is often limited by the low flowering rate of many genotypes. The main purpose of this work was to evaluate the effect of grafting on floral induction of cassava. For this, three genotypes were used: 1) BRS Formosa: a genotype with low flowering rate; 2) BGM0823: a genotype with high flowering rate; and 3) FLA05-02: a genotype of M. esculenta ssp. flabellifolia with high flowering rate. Cleft grafting was performed to generate the following treatments: Self-grafting of: 1) BGM0823 (Self-0823); 2) BRS Formosa (Self-Formosa); and 3) FLA05-02 (Self-FLA); and grafting of the genotypes, with the first being the scion and the second the rootstock: 4) BGM0823 × BRS Formosa; 5) BGM0823 × FLA05-02; 6) FLA05-02 × BRS Formosa; 7) FLA05-02 × BGM0823; 8) BRS Formosa × BGM0823; 9) BRS Formosa × FLA05-02; and also ungrafted treatments: 10) BGM0823; 11) BRS Formosa; and 12) FLA05-02. The results showed a 201% increase in the production of male flowers, 560% of female flowers and 400% of fruits in BRS Formosa grafted on BGM0823. BGM0823 (rootstock) also increased fruit production by 190% of FLA05-02. The grafted cassava plants exhibited an increase on the shoot production, although there was no change in the fresh root yield. The grafting of genotypes with high flowering rates can induce flowering in genotypes with low flowering rates.

Highlights

Cassava (Manihot esculenta Crantz) has gained importance in recent decades due to its many forms of use: as human food, in which it is considered a food security crop and is part of the diet of 800 million people in the tropics (El-Sharkawy, 2012); as animal feed; and for various industrial uses, including to make biofuels
Three genotypes belonging to the Cassava Germplasm Bank (CGB) of Embrapa Mandioca e Fruticultura were selected: 1) BRS Formosa (M. esculenta), an elite genotype introduced by Embrapa that has a low flowering rate; 2) BGM0823 (M. esculenta), a genotype of the CGB that has a high natural flowering rate; and 3) FLA05-02, a genotype of M. esculenta ssp. flabellifolia, a subspecies that has a high flowering rate
The survival rate obtained by cleft grafting ranged from 46% to 88%, depending on the scion-rootstock combination

Summary

Introduction

Cassava (Manihot esculenta Crantz) has gained importance in recent decades due to its many forms of use: as human food, in which it is considered a food security crop and is part of the diet of 800 million people in the tropics (El-Sharkawy, 2012); as animal feed; and for various industrial uses, including to make biofuels. The production of fertile flowers is a basic premise for plant breeding, but obtaining flowers in a synchronized manner and within a suitable time interval is a major challenge (McGarry et al, 2017), considering that some genotypes do not produce flowers (Ceballos et al, 2017). Erect and late-branching plants are preferred by farmers due to the greater ease of crop handling and possibility of using mechanized planting systems. These plants do not bloom or bloom poorly during the normal growing cycle. The use of erect or late-branching genotypes as progenitors in recurrent selection cycles results in limited production of seed, so it is necessary to search for alternatives to induce flowering

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