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In potato breeding and selection, storability should be regarded as equally important as yield, disease resistance, and quality. A study documenting the dormancy period, sprouting behavior, and weight loss of 17 International Potato Center potato elite and advanced clones was carried out in Tashkent, Uzbekistan, under cellar and cold store conditions, during 2008 and 2009. Ninety tubers of each of 17 clones were allocated to experimental units of 30 tubers each placed in trays and randomized in three replications following a random complete block design. Therefore, there were three replications of 30 seed tubers each per entry. The dormancy period ranged from 77 to 115 days and from 100 to 186 days under cellar and cold storage, respectively. There was a relatively high positive correlation (0.69) for dormancy period between storage systems, indicating that clones demonstrating longer and shorter dormancy periods under one system will also behave similarly under the other system. A negative correlation (−0.53 and −0.88) was found between dormancy period and length of the longest sprout in cellar and cold store, respectively, meaning that clones with shorter dormancy often showed a greater length of their longest sprout. The weight loss percentage per tuber was similar in both storage systems, from 5.0% to 8.0% in the cellar and from 5.0% to 9.8% in the cold store, although for different storage periods (an average of 110 and 166 days under cellar and cold storage conditions, respectively). The study indicated that under cellar conditions, clones with a longer dormancy period and slower rate of sprout growth have less weight loss during storage and therefore better keeping quality.  相似文献   
2.
Normalized difference vegetation index (NDVI), which is a measure of leaf greenness (chlorophyll content), is considered to be correlated with crop productivity. This study was conducted to examine genotypic variations for NDVI at different growth stages and its relationship to yield in winter wheat under terminal heat stress. Thirty winter wheat genotypes were evaluated at two locations in 2009–2010 and 2010–2011 in Uzbekistan. The NDVI was recorded at booting, heading, milk and dough stages. The wheat genotypes differed significantly for NDVI at each stage. Grain yield ranged from 3.9 to 6.1 t/ha. Wheat genotypes differed in per cent decline in NDVI from booting to dough stage. However, several high‐yielding genotypes maintained higher NDVI than low‐yielding genotypes when heat stress was evident. The findings suggest change in NDVI during heat stress could be a measure of tolerance. The positive correlation of NDVI with grain yield suggests that it could be used as an indirect selection criterion for identifying physiologically superior, high‐yielding wheat lines under terminal heat stress.  相似文献   
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The levels of magnesium (Mg2+) in irrigation waters and soils are increasing in several irrigation schemes worldwide. Excess levels of Mg2+ in irrigation waters and/or in soils negatively affect soil physical properties (infiltration rate and hydraulic conductivity) and ultimately crop growth and yield. Although few studies have been undertaken on productivity enhancement of magnesium-affected soils by adding a source of calcium (Ca2+) to mitigate the effects of excess Mg2+, there is no information available on optimizing the rate and time of the Ca2+-amendments. A 2-year field study was undertaken in southern Kazakhstan by applying phosphogypsum (PG), a source of Ca2+ and a byproduct of the phosphorous fertilizer industry, to a magnesium-affected soil. There were five treatments with four replications: (1) control (without PG application); (2) PG application in January (before snowfall) equivalent to PG requirement for 0.3 m soil depth (3.3 t ha−1); (3) PG application in January equivalent to PG requirement for 0.6 m soil depth (8.0 t ha−1); (4) PG application in April (after snowmelt) at 3.3 t ha−1; and (5) PG application in April (after snowmelt) at 8.0 t ha−1. All treatment plots were grown with cotton (Gossypium hirsutum L.), which is the most important summer crop in the region. The PG treatments performed significantly better than the control in terms of (1) improved soil quality with a reduction in exchangeable magnesium percentage (EMP) levels; (2) enhanced water movement into and through the soil vis-à-vis increased moisture storage in the root zone for use by the plant roots; (3) increased irrigation efficiency; (4) increased cotton yield and water productivity; and (5) greater financial benefits. In terms of the best rate and time of application, PG applied before the snowfall improved the soil properties to a greater extent than its application in spring after snowmelt. The economic benefits from the amendment application at 3.3 t ha−1 were double those from the treatments where it was applied at 8.0 t ha−1, suggesting that the lower rate was economically optimal. In addition to improving crop productivity, the study demonstrated the beneficial use of an industrial waste material in agriculture.  相似文献   
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