Evaluation of Cassava Germplasm for Productivity<sup>1</sup>

Kawano, Kazuo; Daza, Pablo; Amaya, Alvaro; Rios, Mario; Goncalves, Wania M. F.

doi:10.2135/cropsci1978.0011183x001800030006x

Cited by 47 publications

(32 citation statements)

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“…At an early stage, breeding objectives were directed toward developing high yielding cultivars under favourable conditions in absence of biotic and abiotic stresses (Kawano et al 1978. This strategy was based mainly on the selection for high yield per unit land area (in contrast to traditional vigorous cultivars/landraces suited for intercropping), high dry matter content (i.e.…”

Section: Cassava Research Strategy At Ciatmentioning

confidence: 99%

International research on cassava photosynthesis, productivity, eco-physiology, and responses to environmental stresses in the tropics

El‐Sharkawy¹

2006

Photosynt.

143

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The review sums up research conducted at CIAT within a multidiscipline effort revolving around a strategy for developing improved technologies to increase and sustain cassava productivity, as well as conserving natural resources in the various eco-edaphic zones where the crop is grown, with emphasis on stressful environments. Field research has elucidated several physiological plant mechanisms underlying potentially high productivity under favourable hot-humid environments in the tropics. Most notable is cassava inherent high capacity to assimilate carbon in near optimum environments that correlates with both biological productivity and root yield across a wide range of germplasm grown in diverse environments. Cassava leaves possess elevated activities of the C 4 phosphoenolpyruvate carboxylase (PEPC) that also correlate with leaf net photosynthetic rate (P N ) in field-grown plants, indicating the importance of selection for high P N . Under certain conditions such leaves exhibit an interesting photosynthetic C 3 -C 4 intermediate behaviour which may have important implications in future selection efforts. In addition to leaf P N , yield is correlated with seasonal mean leaf area index (i.e. leaf area duration, LAD). Under prolonged water shortages in seasonally dry and semiarid zones, the crop, once established, tolerates stress and produces reasonably well compared to other food crops (e.g. in semiarid environments with less than 700 mm of annual rain, improved cultivars can yield over 3 t ha −1 oven-dried storage roots). The underlying mechanisms for such tolerance include stomatal sensitivity to atmospheric and edaphic water deficits, coupled with deep rooting capacities that prevent severe leaf dehydration, i.e. stress avoidance mechanisms, and reduced leaf canopy with reasonable photosynthesis over the leaf life span. Another stress-mitigating plant trait is the capacity to recover from stress, once water is available, by forming new leaves with even higher P N , compared to those in nonstressed crops. Under extended stress, reductions are larger in shoot biomass than in storage root, resulting in higher harvest indices. Cassava conserves water by slowly depleting available water from deep soil layers, leading to higher seasonal crop water-use and nutrient-use efficiencies. In dry environments LAD and resistance to pests and diseases are critical for sustainable yields. In semiarid zones the crop survives but requires a second wet cycle to achieve high yields and high dry matter contents in storage roots. Selection and breeding for early bulking and for medium/short-stemmed cultivars is advantageous under semiarid conditions. When grown in cooler zones such as in tropical high altitudes and in low-land sub-tropics, leaf P N is greatly reduced and growth is slower. Thus, the crop requires longer period for a reasonable productivity. There is a need to select and breed for more cold-tolerant genotypes. Selection of parental materials for tolerance to water stress and infertile soils has resulted in breeding ...

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Section: Cassava Research Strategy At Ciatmentioning

confidence: 99%

International research on cassava photosynthesis, productivity, eco-physiology, and responses to environmental stresses in the tropics

El‐Sharkawy¹

2006

Photosynt.

143

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“…Japanese scientists (cited in El-Sharkawy and Hesketh 1964) also had been working in the field for some time on photosynthesis of rice. We early recognized the importance of germ-plasm-based physiological and agronomical research under field conditions as in cotton ), cereals (El-Sharkawy 1975, and cassava (Kawano et al 1978, Connor and Cock 1981, Connor et al 1981, Veltkamp 1985, El-Sharkawy and Cock 1987b, Cock and El-Sharkawy 1988, El-Sharkawy 1990, 1993, 2003, Hershey and Jennings 1992, Pellet and El-Sharkawy 1993a,b, 1997, DeTafur et al 1997a,b, El-Sharkawy and Cadavid 2000, 2002. All of these efforts have led to a better characterization of varietal and genotypic performances under different environments, and elucidation of mechanisms underlying productivity and tolerance to stresses and the identification of useful plant traits for breeding and selection for better adapted and high yielding new cultivars.…”

Section: Responses To Stress: Acclimation Vs Adaptationmentioning

confidence: 99%

“…Kawano et al (1978Kawano et al ( , 1998, Veltkamp (1985), El-Sharkawy and Cock (1987b, Cock and El-Sharkawy (1988), , 1992b, CIAT (1992-95), El-Sharkawy (1993, 2003, El-Sharkawy (1993a,b, 1997), DeTafur et al (1997a,b), and El-Sharkawy and Cadavid (2000,2002) took the plant ideotype approach, searching for form and function traits that might lead to higher yields. This effort, of course, lays the groundwork for post-genomic studies of how plant processes and their interactions in a crop simulation model are controlled by genes or gene function (Fregene et al 2001, Akano et al 2002, Fregene and Puonti-Kaerlas 2002, Okogbenin and Fregene 2002.…”

Section: History Of Cropping Systems' Models and Related Ongoing Resementioning

confidence: 99%

How can calibrated research-based models be improved for use as a tool in identifying genes controlling crop tolerance to environmental stresses in the era of genomics-from an experimentalist's perspective

El‐Sharkawy¹

2005

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Almost four decades have passed since the new field of ecosystem simulation sprang into full force as an added tool for a sound research in an ever-advancing scientific front. The enormous advances and new discoveries that recently took place in the field of molecular biology and basic genetics added more effective tools, have strengthened and increased the efficiency of science outputs in various areas, particularly in basic biological sciences. Now, we are entering into a more promising stage in science, i.e. 'post-genomics', where both simulation modelling and molecular biology tools are integral parts of experimental research in agricultural sciences. I briefly review the history of simulation of crop/ environment systems in the light of advances in molecular biology, and most importantly the essential role of experimental research in developing and constructing more meaningful and effective models and technologies. Such anticipated technologies are expected to lead into better management of natural resources in relation to crop communities in particular and plant ecosystems in general, that might enhance productivity faster. Emphasis is placed on developing new technologies to improve agricultural productivity under stressful environments and to ensure sustainable economic development. The latter is essential since available natural resources, particularly land and water, are increasingly limiting.

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“…After seven months, the accessions from clonal cleaning underwent agronomic characterization by means of the following analysis: plant height, in m; shoot weight, kg pl -1 ; number of roots per plant; root weight per plant, kg -1 pl; root length, cm pl -1 ; root diameter, cm pl -1 ; dry matter content (measured by hydrostatic balance, according to Kawano et al (1978), in %; and starch production (considering root weight and dry weight), g pl -1 . The root length and root diameter traits were measured in three roots of each plant.…”

Section: Planting In the Field And Further Agronomic Characterizationmentioning

confidence: 99%

Agronomic performance of cassava genotypes from the in vitro shoot tip culture submitted to clonal cleaning

Carvalho¹,

Oliveira²,

Souza³

et al. 2017

Biosci. J.

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ABSTRACT:This study aimed to evaluate the agronomic performance of cassava genotypes from the in vitro shoot tip culture to eliminate the cassava frogskin disease for several root and aerial part characteristics. Cassava plants from accessions BGM0315, BGM0464 and BGM0841 infected with cassava frogskin disease were grown in a greenhouse after clonal cleaning. Cuttings from the three accessions were subjected to tetracycline concentrations (0, 5, 10 and 15 mg L -1 ) for three minutes, and then maintained in an acclimatized chamber (35 ± 1 °C and 16 hour photoperiod). Shoots were disinfected for excising shoot tips (0.2 mm and 0.4 mm) and inoculated in a culture medium containing the same concentrations of tetracycline used in the cuttings. After 60 days of cultivation, the explants were transferred to medium without antibiotic, 30 days later they were acclimatized for a period of 70 days for subsequent planting in the field. Seven months after planting, agronomical evaluation was held for root and aerial part characteristics. No influence of isolated shoot tip size was noticed on agronomic characteristics, while the addition of tetracycline in the culture medium, specifically at the concentrations of 5 mg L -1 and 15 mg L -1 , was favorable to the development of the root system of plants in the field. The results revealed that the agronomic performance of cassava plants derived from in vitro cultivation are higher for the production of basic propagation material for the following production cycles, as well as root production for commercial use with subsequent generation of income.

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Evaluation of Cassava Germplasm for Productivity¹

Cited by 47 publications

References 0 publications

International research on cassava photosynthesis, productivity, eco-physiology, and responses to environmental stresses in the tropics

International research on cassava photosynthesis, productivity, eco-physiology, and responses to environmental stresses in the tropics

How can calibrated research-based models be improved for use as a tool in identifying genes controlling crop tolerance to environmental stresses in the era of genomics-from an experimentalist's perspective

Agronomic performance of cassava genotypes from the in vitro shoot tip culture submitted to clonal cleaning

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Evaluation of Cassava Germplasm for Productivity1

Cited by 47 publications

References 0 publications

International research on cassava photosynthesis, productivity, eco-physiology, and responses to environmental stresses in the tropics

International research on cassava photosynthesis, productivity, eco-physiology, and responses to environmental stresses in the tropics

How can calibrated research-based models be improved for use as a tool in identifying genes controlling crop tolerance to environmental stresses in the era of genomics-from an experimentalist's perspective

Agronomic performance of cassava genotypes from the in vitro shoot tip culture submitted to clonal cleaning

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Evaluation of Cassava Germplasm for Productivity¹