排序方式： 共有13条查询结果，搜索用时 203 毫秒
11.
Abstract An established banana field was treated by applying three compounds, fenamiphos, isazofos and carbofuran, to the soil around each mat. The tested compounds were found to reduce significantly soil and root nematode populations. The production cycle of the nematocide treatments was 24 days faster than that of the untreated control. Application of the above chemicals enhanced to the total production of banana. Carbofuran may be ranked top of these nematocides, followed by isazofos. Application of 2 g a.i. of carbofuran three times at intervals of 4 months, yielded 2.66 tonnes per acre more than that of the control. 相似文献
12.
Hussien A. Hebicha Gamal O. El Naggar Ahmed M. Nasr-Allah 《Journal Of Applied Aquaculture》2013,25(3):227-238
Econometric techniques were used to estimate a production function for tilapia pond culture in El-Fayum Governorate, Egypt, utilizing cross-sectional field data. Explanatory variables were feed, initial stocking weight, and pond size. The function was used to examine returns to scale, estimate the productivity of feed and initial stocking weight, and estimate the profit maximizing demand equations for feed and fingerlings. Diminishing returns to scale seem to exist for tilapia pond culture. Optimal economic stocking and feeding rates, yield, and profits for the whole sample were estimated at prevailing prices. Results indicated that producers were using stocking rates greater than the optimal by 36% to 115% and using insufficient feed by 8% to 22%. Investigation of the effects of changes in tilapia selling price and feed price on optimal stocking and feeding rates, yield, and profits showed that a change in tilapia selling price has greater effect on profits, yield, stocking, and feeding rates than a proportional change in feed price. Profits, feeding, and stocking rates are more sensitive than yield to changes in selling price, while feeding rate is more sensitive than stocking rate, yield, and profits to changes in feed price. 相似文献
13.
Diversity in root traits of sorghum genotypes in response to Striga hermonthica infestation 
下载免费PDF全文
下载免费PDF全文 Striga hermonthica is a major biotic constraint to agriculture in the lowland areas of Ethiopia where sorghum is a major stable crop. A pot and a field experiment were conducted in 2011 during the rainy season using 10 sorghum genotypes. Each experiment had infested and non‐infested conditions as the main plots and the 10 genotypes as subplots. The aim of this study was to examine the response of root traits of the sorghum genotypes to S. hermonthica infested conditions and to investigate relationships among S. hermonthica, root and growth traits of sorghum genotypes. Sorghum genotypes were categorized in to three groups, that is, low, moderate and high S. hermonthica count groups. Each group showed a differential response to root traits. Low S. hermonthica count groups had significantly lower root length, root length density, root to shoot ratio and root dry weight compared with susceptible groups. In contrast to low S. hermonthica count groups, moderate S. hermonthica count groups had higher root length, root length density, root to shoot ratio and root dry weight. Highly significant and strong relations were observed among root traits of sorghum, indicating that any of the root traits can be used as indicators for resistance. The result indicates different reactions in root traits in the upper soil layer may be useful for genetic improvement of S. hermonthica resistance and tolerance breeding in sorghum. 相似文献