Responses of three early potato cultivars to subsoiling and irrigation regime on a sandy soil

A compact subsoil restricts rooting and reduces the volume of soil from which plant roots can obtain water and nutrients. A reduced water supply may result in severe plant water stress between irrigations. A study was conducted on a sandy soil to evaluate the responses of three early potato cultivars (Norgold Russet, HiLite Russet, and Russet Norkotah) to subsoiling to loosen a compact subsoil and to four irrigation regimes. Differences among cultivar responses to irrigation and subsoiling treatments were minor. All performed best with daily irrigation to replace évapotranspiration (ET) and poorest when irrigation was interrupted during tuber bulking. With daily irrigation to replace ET, subsoiling had little benefit, but with inadequate irrigation, subsoiling improved yield and quality of tubers compared to not subsoiling. Averaged over all treatments, HiLite was the lowest yielding cultivar and had the least U.S. No. 1 and the most undersize tubers. Norkotah had the most U.S. No. 1 and the fewest undersize tubers.     

Chemical control of pink rot of potato (Phytophthora erythroseptica PethyB.)

Field trials have been carried out for seven years to control pink rot (Phytophthora erythroseptica) at the International Potato Center (CIP). This disease has been a serious problem in the maintenance of a germplasm collection at the CIP’s Experimental Station at Huancayo, Peru (3300 m.a. s.l.). Pink rot annually causes serious loss of germplasm accessions, particularly diploid cultivars. Protective and systemic soil fungicides and soil fumigation with Basamid (Dazomet 98%) did not diminish the incidence of pink rot. Ridomil 5G (Metalaxyl 5%) applied at planting time with a preplanting fumigant reduced disease incidence from 31% of infected tubers to around 1%. Optimum control and yield increase were achieved by using Basamid at 300 kg/ha + Ridomil 5G at 30 kg/ha.     

茶业电子商务的现状与对策

本文从茶商的角度,分析电子商务时代的到来给茶商带来什么样的机会,介绍当前茶业电子商务的现状,剖析茶业电子商务应用过程中存在的问题,提出茶商应如何开展电子商务,最后展望茶业电子商务的前景。     

Field screening for resistance to potato smut in Peru

Field trials carried out between 1982 and 1984 to evaluate potato clones and cultivars for their resistance to potato smut indicated that from a total of 179 accessions tested seven were resistant during the three-year tests. Five accessions were resistant during two consecutive trials but then there were not enough tubers available for a retest for the third time. Accessions that were resistant during the three consecutive field trials included Peruvian cultivars Cuzco, Mariva, Mi Peru, Participación and Revolución, and CIP’s clones 376181.5 and 6956.52.     

Variations in responses of potato germplasm to deficit irrigation as affected by soil texture

The response to irrigation of three parental potato cultivars was studied on loam and sandy soils by use of the line source sprinkler technique, which provided a continuous irrigation variable from 0 to 100% or more replacement of estimated evapotranspiration (Et). Solid-set sprinkler irrigation from planting until near full ground cover provided optimal early plant growth and a soil profile filled with water when the irrigation variable was started in July. On the loam soil this residual soil water provided most of the water needs of the three cultivars over a 10–12 week period until harvest. On this soil, irrigation levels providing replacement above 20 to 40% Et had little beneficial effect. In fact, higher irrigation levels had serious deleterious effects, especially on grade and solids of Nooksack. On the loam soil, Nooksack performed best in every regard at deficit irrigation levels below 50% Et. In contrast, on this loam soil, differing irrigation levels had very little effect on the productivity of Lemhi. The response of all cultivars on sandy soil was much different than on loam soil. On sand, total and U.S. No. 1 yield of all cultivars increased greatly as irrigation levels increased, up to 70 to 80% Et. Levels above this had minimal effect. Nooksack again performed better than the other two cultivars under deficit irrigation. The results of these and other studies show there is potential for identifying or developing potato cultivars which are more efficient users of irrigation water.     

Chilean hazelnut butter,a new alternative for consumers

Four formulations of Chilean hazelnut butter were prepared containing Chilean hazelnut paste and 5%, 10%, 15% and 20% margarine. As the level of margarine was increased to 20%, the protein and crude fiber content decreased markedly, while those of moisture, crude fat and calories increased. After 90 days of storage, neither the samples stored at 5°C nor those stored at 15°C showed any objectionable effects both from the bacteriological and chemical point of view. Sensory analyses, including quality and acceptability studies, were performed on the various blends. Flavor, color and taste were improved by the addition of margarine to the butter formulas. It is concluded, therefore, that Chilean hazelnut butter represents a new and interesting alternative for human nourishment.     

Potato cultivars: Genetic variation within putative clones

Four of five major cultivars of the potato (Solanum tuberosum L. ssp.tuberosum) from different sources were found to vary genetically. This variability was detected by an electrophoretic study of enzymatic activity for alkaline phosphatase and glucosephosphate isomerase. An examination of red cultivars from Beltsville, Md. suggests that the apparent intracultivar variability observed for Red Pontiac may be due to cultivar mislabeling rather than mutation or mitotic recombination. The results of this study raise concerns about potato cultivar certification and interpretations of some of the previous cultivar work. We suggest that a more extensive survey of intracultivar variability be carried out. Further, we suggest that these genetic markers and others could be used in cultivar identification.     

Context matters: the landscape matrix determines the population genetic structure of temperate forest herbs across Europe

Landscape Ecology - Plant populations in agricultural landscapes are mostly fragmented and their functional connectivity often depends on seed and pollen dispersal by animals. However, little is...