Effect of pruning young branches on fruit and seed set in cassava

Flowering in cassava is closely linked with branching. Early-flowering genotypes branch low and abundantly. Although farmers prefer late flowering genotypes because of their erect plant architecture, their usefulness as progenitors in breeding is limited by their low seed production. In general, the first inflorescence aborts in cassava. Preventing this abortion would result in early production of seeds and make cassava breeding more efficient. The objective of this study was to assess if pruning young branches prevents the abortion of first inflorescences and promotes early fruit and seed set. Four genotypes with early, late, very late, and no flowering habits were grown under an extended photoperiod (EP) or normal dark night conditions (DN). Additional treatments included pruning young branches at the first or second flowering event and spraying (or not) benzyladenine (BA) after pruning. One genotype failed to flower and was not considered further. For the remaining genotypes, EP proved crucial to induce an earlier flowering, which is a pre-requisite for pruning. Total production of seeds in EP plots was 2,971 versus 150 in DN plots. For plants grown under EP, the average number of seeds per plant without pruning was 3.88, whereas those pruned produced 17.60 seeds per plant. Pruning at the first branching event led to higher number of seeds per plant (26.25) than pruning at the second flowering event (8.95). In general, applying BA was beneficial (38.52 and 13.98 seeds/plant with or without spraying it, respectively). The best combination of treatments was different for each genotype. Pruning young branches and applying BA in the first flowering event not only prevented the abortion of inflorescences but also induced the feminization of male flowers into hermaphrodite or female-only flowers. The procedures suggested from this study (combining EP, pruning young branches, and spraying BA), allowed the production of a high number of seeds from erect cassava genotypes in a short period. The implementation of these procedures will improve the breeding efficiency in cassava

Present situation and future potential of cassava in China

In China, cassava is planted mainly in the southern provinces of Guangxi, Guangdong, Hainan and Yunnan. The annual total area and production is about 400,000 ha and 6,000,000 tonnes of fresh roots, respectively. Guangxi is the main cassava producing province with more than 60% of both cassava growing area and production. Following the success of research on cassava product development and the development and dissemination of promising varieties, the cassava yield in the province has increased substantially during the last ten years. The cassava processing industry is mainly concentrated in Guangxi and Guangdong provinces. Of the approximately 525,000 tonnes of cassava-based products processed annually in China, 73% comes from Guangxi, about 20% from Guangdong, 6% from Hainan and 2% from Yunnan. About 95% of these products are starch or modified starch. Considering the natural resource conditions and the rapid development of the cassava industry in Guangxi, it is clear that the present status and future potential of the cassava industry is more favorable in this province as compared to other provinces. Especially since the beginning of the 1990s, the cassava industry in Guangxi developed very fast. In view of the great potential to further develop this crop, the government of Guangxi has organized a group of experts to work out a future plan of cassava development in Guangxi for the next 20 years. Other cassava producing provinces have not yet developed similar plans

Cassava agronomy research and adoption of improved practices in China: Major achievements during the past 20 years

During the past 20 years, cassava agronomy research in China placed major emphasis on fertility maintenance, erosion control, planting methods, time of planting and harvesting, etc. Longterm fertilization trials conducted at GSCRI, CATAS and the Upland Crops Research Institute (UCRI) in Guangzhou, Guangdong, indicate that N was the most important nutrient for increasing cassava root yields during the early cropping cycles of cassava, but that K, and in some cases P, also became increasingly important. Results of soil erosion control trials conducted in Hainan and Guangxi showed that contour ridging, intercropping with peanut or the planting of vetiver grass contour hedgerows were the most effective practices for reducing soil erosion when cassava was grown on slopes. Planting cassava stakes vertically resulted in more rapid sprouting than horizontal or inclined planting, but there was not much difference in root yield among several methods of planting. Research on time of planting and harvesting cassava conducted at CATAS indicate that when cassava was harvested at 8 months after planting, highest yields were obtained when cassava was planted during the spring (Feb-May). However, when cassava was harvested at 12 months, time of planting had no consistent effect on yield. Effect of time of fertilizer application on cassava yield conducted at CATAS showed that a basal fertilizer application at 30 days after planting resulted in highest yields; there were no significant differences between a single application at 30 days and split applications at 30 and 60 days, or at 30, 60 and 90 days

Recent progress in cassava agronomy research in China

In recent years, cassava agronomy research in China has emphasized soil fertility maintenance, erosion control, planting methods and date of planting and harvesting. The research was conducted in cooperation between the Guangxi Subtropical Crops Research Institute, the South China Academy of Tropical Crops, and the Upland Crops Research Institute with CIAT. Results of three long-term fertility trials indicate that fertilizer application markedly increased cassava root yields. But different varieties showed a different response to fertilizers. SC205 was more responsive to fertilizer application than SC201 or SC124; high rates of fertilizers resulted in high yields of SC205, but not of SC201 or SCI 24. The experiments also showed that during four cropping cycles of cassava in southern China, N was the most important nutrient for increasing cassava root yields, but that K and in some cases P also became increasingly important. Application of farm yard manure or burned soil, in addition to medium levels of chemical fertilizers, had no significant effect on increasing cassava root yields. Experiments on soil erosion control conducted in Hainan and Guangxi showed that contour ridging, intercropping with peanut, or barrier strips of Brachiaria pasture were the most effective practices for reducing soil erosion when planting cassava. Intercropping of cassava with peanut or cassava with seed watermelon increased income more than 65-200% compared with cassava monoculture. Cassava grown with Stylosanthes guianensis barriers reduced soil erosion 14-27%, while increasing income 23-43%. Among several methods of planting cassava, vertical planting resulted in more rapid sprouting than horizontal or inclined planting, especially during periods of drought, but root yields were not significantly different. Among planting on the flat, or on single-row or double-row ridges, there was not much difference in germination and root yield. Research to determine the optimum time of planting and harvest of cassava, conducted at SCATC, showed that when cassava was harvested at 8 months after planting, highest yields were obtained when cassava was planted during the spring (Feb- May); however, when cassava was harvested at 12 months, time of planting had no consistent effect on yield

Recent progress in cassava varietal improvement in China

The paper discusses the research progress mainly for the period of 1990-1993. There are three institutions, SCATC, UCRI and GSCRI, which are systematically working on cassava breeding in China. Since the principal constraint to cassava varietal improvement is the lack of genetic variability, the main approach currently used is the evaluation and selection of hybrid seeds introduced from CIAT/Colombia and from the Thai-CIAT program. In the past few years, remarkable progress has been made in these three institutions, mainly as follows: 1) At SCATC, advanced clones continue to show promising results in comparison with the respectable local control (SC205). Many high-yielding clones were identified in preliminary trials, in which Thai-CIAT material showed a clearly superior performance. 2) At UCRI of the Guangdong Academy of Agric. Sciences, very convincing yield data of a pre-released clone (ZM8002) were obtained from four years of regional trials and another three years of demonstration trials. In addition, many clearly superior new clones were selected from CIAT seed material in a replicated yield trial, nearly doubling the yields of ZM48002 or SC201. Two advanced clones, selected from locally hybridized seeds, showed a high yield potential. 3) At GSCRI, several clones selected from ClAT-introduced seeds showed for the first time a clearly superior yield and dry matter content over local controls in 1992. 4) Additional genetic variability was obtained at SCATC through induced mutations using colchicine treatments. These mutants are presently being evaluate

A historical account of progress made in cassava varietal improvement in China

Cassava varietal improvement in China has historically been conducted by collecting and evaluating local varieties, by introducing and testing of cassava germplasm from abroad, followed by the establishment of a cassava cross-breeding program. Considerable progresses has been made in the following areas: a) Collection and evaluation of the local varieties, SC205 and SC201 and their extension over a wide range of growing conditions, so as to expand their growing range and planting area b) Setting up a cassava germplasm bank to conduct cross-breeding of cassava c) Establishing a nation-wide cassava regional trial network, which forms an integral part of the breeding program, in order to develop improved varieties, test and demonstrate as well as extent new higher-yielding cassava varieties d) Selection of many promising clones e) Release of some improved varieties. The cassava breeding program in China was started in the 1960s when several good local varieties were collected, evaluated and released. It was shown that cassava can be planted in the region south of Qinling Huaihe and the Yangtse river basin, in those areas having a mean annual temperature above 18o C and a frost-free period of more than 8 months of the year. Since the 1970s marked progress has been made by adopting an integrated system of germplasm introduction and breeding, with the major objectives of high yield, high starch content and resistance to wind. A nation-wide cassava trial network was established to form part of this integrated breeding system to produce improved varieties, test, select and demonstrate as well as extend these new varieties. Some of these improved varieties, such as SC6068, SC124, SC8002, SC8013, Nanzhi-188, GR891 and GR911, have been released. They are now grown in an area of about 50,000 ha and outyield the local clones by about 20%, increasing farmers’ income by more than 3.4 million yuan. In recent years the cassava breeding program in China has been capable of annually producing more than 3000 hybrid seeds from 80-100 cross combinations, as well as evaluating 2000-3000 hybrid seeds introduced from CIAT/Colombia and the Thai-CIAT program. More than 500 promising clones have been selected, of which OMR33-10-4, ZM8641 and ZM9057 will be further tested and examined for release. In addition, many promising clones, such as CMR34-11-4, OMR36-63-6, OMR37-103-1, OMR37-14-9, CMR38-163-4, SM2323-6 and ZM9244, which are characterized by high yield and high dry matter content, can be used in the future in the cassava varietal improvement program in China

Retroperitoneal Laparoscopic Nephroureterectomy for Tuberculous Nonfunctioning Kidneys: a single-center experience

Purpose To present our surgical techniques and experiences of retroperitoneal laparoscopic nephroureterectomy for the treatment of tuberculous nonfunctioning kidneys. Materials and Methods From March 2005 to March 2013, a total of 51 patients with tuberculous nonfunctioning kidney underwent retroperitoneal laparoscopic nephroureterectomy at our medical center. The techniques included early control of renal vessels and dissection of the diseased kidney along the underlying layer outside the Gerato’s fascia. The distal ureter was dissected through a Gibson incision and the entire specimen was removed en bloc from the incision. Patient demographics, perioperative characteristics and laboratory parameters as well as postoperative outcome were retrospectively reviewed. Results Retroperitoneal laparoscopic nephroureterectomy was successfully performed in 50 patients, whereas one case required conversion to open surgery due to non-progression of dissection. The mean operating time was 123.0 minutes (107-160 minutes) and the mean estimated blood loss was 134 mL (80-650 mL).The mean postoperative hospital stay was 3.6 days (3-5days) and the mean return to normal activity was 11.6 days (10-14days). Most intra-operative and post-operative complications were minor complications and can be managed conservatively. After 68 months (12-96 months) follow-up, the outcome was satisfactory, and ureteral stump syndrome did not occur. Conclusions Retroperitoneal laparoscopic nephroureterectomy as a minimally invasive treatment option is feasible for treatment of tuberculous nonfunctioning kidneys