Sugarcane Underground Organs: Going Deep for Sustainable Production

Abstract

Sugarcane breeding has greatly advanced in recent decades, but many aspects of sugarcane physiology are still poorly understood, including the root-shoot relationships that ultimately affect yield. Traditional methods for studying root systems are imprecise due to methodological difficulties of in situ assessment and sampling; this seems especially true for the sugarcane root system. Studies on sugarcane roots lag well behind those on other crops, in part due to the large plant stature and long crop cycle. Commercial sugarcane cultivars are hybrids from crosses mostly between Saccharum officinarum and S. spontaneum made by breeders at the beginning of the last century. These hybrids have a genomic structure composed of 80% S. officinarum, 10% S. spontaneum and 10% recombinants of these two species. S. spontaneum is included in large part for the robustness of its underground organs (root and rhizome). The S. spontaneum genes controlling these characteristics may be lost during recurrent backcrosses with S. officinarum to increase sugar content and yield. Thus, ratooning ability is one of the most desired traits. Ratooning ability comes mainly from the rhizomatousness of S. spontaneum, but this trait has been diluted during the selection process so that the stubble of hybrids does not have rhizomes sensu stricto. In this review, we revisit some basic aspects of the sugarcane root system, mainly from an ecophysiological view, and point out considerations for breeders to consider in designing the architecture of a new sugarcane cultivar that can meet the need for sustainable agricultural production.

Input of sugarcane post-harvest residues into the soil

“…Besides being a signifi cant source of C to the soil, rhizomes play an important role on the sugarcane ability to survive in harsh environments, mainly due its capability of tillering (Paterson, 2009). Added to this, a good ratoonability in sugarcane is undoubtedly linked to high tillering which, in turn, is linked to the amount and vitality of rhizomes (Matsuoka and Garcia, 2011). Moreover, Vitti et al (2007) verifi ed a positive correlation among nutrients reserves into rhizomes and stalk production of consecutive sugarcane ratoons.…”

Energy Cane: Its Concept, Development, Characteristics, and Prospects

“…Modern studies are confirming claims that those latter two species are not true species and should rather be considered as horticultural groups (cultigens) that originated from natural crosses between S. officinarum and S. spontaneum (see revision in [46,118]). As such, it is reasonable to speculate that their shorter rhizomes are result of the dilution of the original rhizomatous trait of S. spontaneum) and are distinguishing characteristics that confer many practical advantages: (1) the plant tolerates drought stress better [111]; (2) the regrowth after the harvest is better [111,119]; (3) the plant more efficiently exploits the soil resources [72]; (4) the protection of the soil against erosion is more efficient [120]; (5) rhizomes aid in sustainable ratooning, an important characteristic for economic and environmental reasons, as discussed elsewhere (e.g., [121,122]) and (6) there is a comparatively higher yield in most environments especially in marginal conditions of soil and climate (actually, all those characteristics are applied to selectable individuals in the population under selection. As indicated in the text, the diversity available in the germplasm bank is so big that the mating possibilities are enormous and, obviously, not all the families or individuals within a family are superior in all the desirable traits).…”

Root extracts of Bracchiaria humidicola andSaccharum spontaneum to increase N use by sugarcane

“…spontaneum, a species that forms the sugarcane hybrids currently cultivated, contributes mainly to provide rusticity and an abundant root system (Matsuoka and Garcia, 2011), and may be a possible source of this characteristic. Largely cultivated in the Brazilian savannas, pastures of B. humidicola and B. decumbens are highly adapted to conditions of low availability of N. In this sense, as reported by Subbarao et al, (2007), it is possible that species better adapted to the Brazilian savannas are provided with mechanisms to conserve and use N efficiently, the main factor limiting growth and yield (Lata et al, 2004).…”