Understanding farmers’ potato production practices and use of improved varieties in Chencha,Ethiopia

This study was carried out to better understand non-adoption of improved varieties of potato (Solanum tuberosum) and associated technologies by smallholder farmers in Chencha, Ethiopia. Data were collected through a survey (n = 47) and in-depth interviews (n = 20). It shows how wealth status was a factor of major importance. Most wealthy and some medium-wealthy farmers adopted improved potato varieties and many of the improved production practices; they had access to seed, associated knowledge and support, and sufficient resources that were necessary to apply the improved practices. Non-adoption was common among many medium-wealthy and most poor farmers: they lacked—next to access to the technologies and knowledge—cash, land, and labor. Results indicated the need to rethink research and intervention efforts. Next to paying attention to differences in the access to technology and the related knowledge, there is a need to consider the variation in technology needs, supporting microcredit services, and room to experiment. As a result, different combinations of improved production practices may be adopted.     

Quality of principal released rice varieties in China

Most of the cultivated rices in China are nonwaxy japonica and indica varieties. According to the the survey of the rice quality on 262 principal released varieties (every variety has been popularized over 6,600 ha) by CNRRI, the average of brown rice recovery is 80% (70—82%) and the head rice recovery is 54% (40—67%)in indica varieties. Most indica varieties have medium long and bold grains with low translucency and high rate of chalky grain and chalkiness. In addition, they possess high amylose content, low to medium gelatinization temperature and medium gel consistency with average 9.8% protein content (6.8% to 13.8%). Only a few indica varieties have extra long or slender grains, high translucency, medium or low amylose content, and soft or hard gel consistency. None of them have high     

Has the introduction of modern rice varieties changed rice genetic diversity in a high-altitude region of Nepal?

We surveyed the uptake of three modern rice varieties by farmers in high-altitude villages in the Kaski district of Nepal and found that their uptake had displaced some traditional landraces in the district. The three varieties, Machhapuchhre-3 (M-3), Machhapuchhre-9 (M-9) and Lumle 2, were developed using client-oriented, participatory plant breeding methods and the first was introduced to farmers in 1996. By 2004 up to 60% of the land area was used to grow these modern varieties. Molecular markers (SSR) were used to assay levels of genetic diversity to test if adoption of modern varieties in the place of landraces had changed genetic diversity. The modern varieties were found to contain diverse alleles with a high proportion from the local parent variety, Chhomrong Dhan. We found a high level of allelic richness in the landraces, and although seven had been dropped in favour of the modern varieties, other diverse landraces were still being cultivated by farmers in the study villages on up to 40% of the rice area. Genetic diversity may be maintained even when landraces are displaced by modern varieties. Using a model we found that the partial replacement of landraces increased genetic diversity if the modern varieties were adopted on up to 65% of the area. Only above these levels did overall diversity decline.     

Is dormancy breaking of potato tubers the reverse of tuber initiation?

Summary Tuber formation is a well orchestrated physiological event that involves many metabolic changes. Dormancy gradually develops in potato tubers from the moment cell division in the stolon tip has stopped and the tuber starts to develop. Dormancy breakage may be the reverse of dormancy initiation suggesting that there may be similarities between tuber induction and dormancy development. Based on a literature review it is concluded that, when comparing tuber induction and the breaking of dormancy, hormonal activities are only partly reversed, whereas carbohydrates and enzyme activities might be reversed. For more definite conclusions more research should be done to assess precisely the moment of dormancy breaking. Moreover, measurements on events associated with tuber induction and dormancy breaking should be carried out using the same techniques and the same material. Molecular genetic analyses may provide well-defined markers for the timing of breaking of dormancy.     

Are more productive varieties of Paspalum dilatatum less tolerant to drought?

Paspalum dilatatum Poir., is a perennial C₄ grass widely distributed in the Argentinean Pampas. The response to water availability for materials developed with forage‐production purposes is unknown. We hypothesized that genetic differences between commercial varieties are reflected in their regrowth capacity under water stress. The effect of five levels of constant water supply on three plant varieties (two derived from apomictic materials: ‘Relincho’ and ‘Alonso’ and one from sexually‐derived material: ‘Primo’) were examined in the greenhouse. Leaf‐ and plant‐response traits were followed during 38 d after a single defoliation event. Seven response variables were measured: three of them were morphogenetic (leaf elongation rate, leaf appearance rate and leaf elongation duration) and four were structural (number of live leaves, lamina length, tiller biomass and tiller production). The sexual material showed higher values for growth variables than the apomictic varieties (leaf elongation rate, leaf length and tiller biomass) across the environmental range. Apomictic varieties showed a proportionally similar drought response to the sexual material for the seven variables. No intra‐specific trade‐off (statistical interaction) was found between growth under high water availability conditions and drought tolerance.     

Growth and nutrient uptake of two varieties of groundnuts under irrigation in Israël

Summary Some data on growth, development, and mineral nutrition of two varieties of groundnuts — Improved Virginia Bunch and Spanish-33 — under irrigation are reported.There was almost no difference in the yield of pods of the two varieties, but the yield of hay was much lower in Spanish. Spanish had also a lower total yield of dry matter, a smaller leaf area, and fewer branches than Virginia.In both varieties a negative correlation was found between Net-Assimilation-Rate and Leaf-Area-Index. Under the conditions of our observations, the highest rate of dry matter accumulation per plant was at a Leaf-Area-Index of approximately 3.There was a gradual decrease in the nitrogen content of the vegetative parts from the beginning of the season until harvest time. Most of the final amount of nitrogen was taken up before the end of August. After that, there was a transportation of this element to the newly formed pods. Pods and kernels of the Spanish variety had a higher nitrogen content than Virginia. The total amount of nitrogen taken up by the plants was equal in both varieties, 22 g per sq.m.A slight decrease in the phosphorus content of the vegetative parts was found throughout the season. The percentages of phosphorus were roughly equal, but the final amounts taken up by the two varieties were different: 3.16 g P per sq.m in Virginia, 2.34 in Spanish. The plants continued to take up phosphorus until harvest time.As the season progressed, the percentages of potassium decreased in the vegetative parts as well as in the pods and pegs. The stems had the highest potassium contents. Almost all the final amount of potassium was taken up by August. Total amounts of potassium taken up by the plants were found to be 5.7 g per sq.m. in Virginia, 3.4 in Spanish.The authors wish to acknowledge the assistance of Miss HelenaBodek in carrying out the chemical analyses. This work was aided by a grant by the Israel Groundnut Production and Marketing Board.

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Zusammenfassung Der Bericht enthält Angaben über Wachstum, Entwicklung und mineralische Ernährung von zwei unter Bewässerung angebauten Erdnuss-Sorten — Improved Virginia Bunch und Spanish — 33.Die zwei Sorten unterschieden sich kaum in ihrem Hülsenertrag, dagegen aber war der Heuertrag der Sorte Spanish erheblich niedriger. Spanish war auch geringer als Virginia in allgemeinem Trockensubstanzertrag, Blattoberfläche und Stengelzahl.In beiden Sorten wurde eine negative Korrelation zwischen Rein-Assimilations-Wert und Blatt-Flächen-Index gefunden. Bei den Bedingungen, unter welchen unsere Beobachtungen angestellt wurden, ergab sich die höchste Trockensubstanzansammlung bei einem Blatt-Flächen-Index von annähernd 3.Eine allmähliche Abnahme des Stickstoffgehalts der vegetativen Organe im Laufe der Entwicklungsperiode bis zur Erntezeit wurde beobachtet. Der Hauptteil der endgültigen Menge des Stickstoffs wurde bis Ende August absorbiert. Nach diesem Termin fand eine Überführung des Stickstoffs in die neugebildeten Hülsen statt. Hülsen sowohl wie Samen der Sorte Spanish hatten einen höheren Stickstoffgehalt als Virginia. Die Gesamtmenge des durch die Pflanzen absorbierten Stickstoffs war in beiden Sorten gleich und betrug 22 g pro m².Eine geringe Abnahme des Phosphorgehalts der vegetativen Organe im Laufe der Entwicklungsperiode wurde festgestellt. Der Prozentsatz des Phosphors der zwei Sorten war beinahe gleich, jedoch die Gesamtmenge des durch die Pflanzen aufgenommenen Phosphors betrug 3.16 g pro m² bei der Sorte Virginia und 2.34 bei der Sorte Spanish. Die Phosphorabsorption der Pflanzen hielt bis zur Enrte an.Im Laufe der Entwicklungsperiode nahm der Kalium Prozentsatz in den vegetativen Organen sowohl wie in den Hülsen und Stielen ab. Die Stengel ergaben den höchsten Kaliumgehalt. Im August war beinahe die endgültige Menge des Kaliums aufgenommen. Die Gesamtmenge des durch die Pflanzen absorbierten Kaliums betrug 5.7 g pro m² bei der Sorte Virginia und 3.4 bei der Sorte Spanish.

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Résumé Quelques données sur la croissance, le développement et la nutrition minérale de deux variétés d'arachides — Improved Virginia Bunch et Spanish 33 sont présentées ici.Les deux variétés ont donné des rendements en gousses très voisins alors que le rendement en foin de la variété Spanish a été très inférieur. Pour la variété Spanish, on a eu, également, un rendement total en matière sèche plus faible, une surface foliaire plus réduite et un nombre de branches moindre que pour la Virginia.Chez les deux variétés, on a trouvé une correlation négative entre le Taux d'Assimilation Nette et l'Index de Surface Foliaire. Dans les conditions de nos observations, le taux maximum d'accumulation de matière sèche correspond à un index voisin de 3.Le taux d'azote contenu dans les organes végétatifs a diminué progressivement du début de la saison jusqu'au moment de la récolte. La plus grande partie de la quantité finale d'azote a été fixée avant la fin août. Après cette date, il y a eu transport de cet élement vers les gousses nouvellement formées. Le taux d'azote des gousses et des graines de la variété Spanish est plus éléve que celui des gousses et graines de Virginia. La quantité totale d'azote prélevé par les plantes a été la même pour les deux variétés, soit 22 g par m².On a noté une légère diminution du taux de phosphore des organes végétatifs au cours de la saison. Les pourcentages de phosphore ont été très voisins, mais les quantités totales prévelées par les plantes des deux variétés ont été différentes: 3.16 g P par m² pour la variété Virginia et 2.34 pour la Spanish. Les plantes ont continué à prélever du phosphore jusqu'au moment de la récolte.A mesure que la saison a avancé, le pourcentage de potassium des organes végétatifs ainsi que des gousses et des gynophores a décru. Les tiges out contenu les taux de potassium les plus élevés. La presque totalité du potassium a été prélevé avant le mois d'août. Les quantités totales de potassium prélevées par les plantes ont été de 5.7 g par m² pour la variété Virginia et de 3.4 pour la variété Spanish.

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With 10 figs.     

Field assessment of imidacloprid to reduce the spread of PVY° and PLRV in potato

A three year field study conducted at the Potato Research Centre in Fredericton, New Brunswick, showed that imidacloprid applied in furrow at planting or twice to the foliage in mid July could result in a limited reduction of PLRV spread in the potato crop. Tests did not determine any significant effect on the reduction of the spread of PVY. The aphicidal property of imidacloprid was confirmed.     

Three years’ comparisons of dusts and bordeaux spray for potato production in Central Jersey

American Journal of Potato Research -     

The location of 5’-nucleotidase in seedling cells in Yunnan rice varieties and the change of enzyme activity after chilling injury

The seedlings of three rice varieties(Damagu,Ligeng 2,and Xiuzinuo)were cultivated at 25