In laboratory conditions were tested some winter wheat varieties (registered in the Slovak Republic) for tolerance to low pH and Al3+ ions in juvenile stage. Experimental plants were cultivated 10 days in air-conditioned chamber in two culture media - in naturally acid soil (pH 4) and in acid nutrient solution with content of 10 ppm Al3+ (pH 4 + Al3+). As standard varieties, the Rumanian tolerant variety Albota and American sensitive variety Scout - 66 were used. The results have shown that these varieties are very suitable for testing of winter wheat varieties for tolerance to low pH and Al3+. From Slovak varieties the most tolerant variety was Rada and the most sensitive Solida. Other varieties rank among medium sensitive and medium tolerant, respectively. Positive correlation between the studied traits suggest that length and weight of roots and leaves can be used equally in testing winter wheat varieties for low pH and Al3+ ions tolerance. Positive correlations between culture media have shown that both media can be used comparably for cultivation and testing for the studied stresses

Eighteen commercial varieties of sweetpotato roots grown in Hawaii were harvested in spring and fall and analyzed for their nutrient compositions. The HPLC analysis of carotenoids showed lower beta-carotene content (13.1 mg/100g fresh weight) in orange fleshed varieties than counterparts analyzed in mainland U.S.A. The beta-carotene content in light yellow and purple fleshed ones were in the range of 0.1-0.6 mg/100g, fresh weight. Alpha-carotene was positively identified in two varieties with Hawaii origins at 0.3 and 1.5 mg/100g fresh weight, respectively. The enzymatic-gravimetric method for the dietary fiber analysis revealed a substantial presence of the soluble fiber. The soluble fiber content in two purple fleshed varieties was approximately half of the total fiber content. Total fiber contents were in the range of 2.01-3.87 g/100g fresh weight, higher than previously reported.

The aim of this work was to investigate the possibility of using winter wheat genetic resources tolerant or sensitive to low pH and Al3+ ions. At two pH levels of nutrient solution (pH 4 plus Al3+ and pH 7 without Al3+), after hydroponic way of cultivation (12 days) juvenile plants of winter wheat (phase of 2nd leaf) have been tested for tolerance to low pH and Al3+ ions. There were evaluated varieties and hybrid populations of F2 generation of tolerant and sensitive varieties Albota and Scout-66 with varieties (Torysa, Barbara, Livia, Ilona, Py-11). As a check varieties were cultivated foreign tolerant varieties Albota and Atlas-66 and as a sensitive variety Scout-66. There were evaluated following traits: length and weight of roots, length and weight of above ground parts. The results have shown that the check varieties are more tolerant respectively more sensitive as our registered varieties. More tolerant and more sensitive are also hybrid of these variety combinations what confirm differences mainly between length and roots weight of plants cultivated in the acid medium with Al3+. From these results follows, that tolerant variety Albota could be used in breeding process as a donor for transmission of tolerance property

In rainfed lowland, use of wet seeding in rice is increasing because of inadequate labor for transplanting and the need to increase cropping intensity. The establishment of a vigorous plant stand with adequate weed suppression is a major constraint to wet-seeded rice. A better understanding of variation in seed and seedling vigor and the implications for yield stability is needed. This paper examines variation in seed vigor in the germination cabinet of four varieties under four temperature regimes using two seed sources and two seed ages. Variation in seedling vigor is then examined using the same varieties and seed ages, but with four nutrient treatments in two water regimes in the greenhouse. In the germination cabinet, variation in seed vigor was dominated by the interaction between variety and temperature, with only 3 percent of the variation contributed by seed age. Germination of IR20 was less affected than those of other varieties at 15 deg C; germination was less in NSG19, slower in IR72, and slower and less in PSBRc 14. Model-based analysis was then used to examine base temperature and temperature responsiveness of the varieties in relation to seed lot. In the greenhouse, variation in seedling vigor was dominated by two interactions: between water and variety, and among water, nutrient and seed age. Seedling vigor was more severely reduced by water stress when N was applied as urea and when aged seeds were used. Water stress reduced the seedling vigor of NS19 and IR72 more severely. The results demonstrate a substantial capacity to manipulate seed and seedling vigor in wet-seeded rice. Subsequent experiments will examine the implications for yield performance and stability

Input-responsive, high yielding rice varieties and associated technologies responsible for the doubling of yields on irrigated lands in Asia have not suited the area of more than 40 million hectares of Asian rainfed lowland rice. These environments are home to some of the poorest rural populations in South and Southeast Asia, and the rice crops are subject to drought, prolonged submergence from uncontrolled flooding and nutrient deficiencies. Farmers grow unimproved varieties and these, combined with abiotic stresses and low inputs, result in grain yields often less than 2 t ha(-1). The International Rice Research Institute (IRRI) and National Agricultural Research Systems (NARS) have recently joined to form the Rainfed Lowland Rice Research Consortium in order to identify, prioritize and execute strategic research that addresses critical yield and productivity constraints. Principal intervention points for achieving sustainable yield increases are in developing drought- and submergence-tolerant germplasm with good yield potential, improved nutrient management under stress conditions, water use-efficient crop establishment practices, and understanding farmers' approaches to risk management. Multidisciplinary teams of IRRI and NARS scientists execute research at sites selected across the region to represent the key sets of constraints.

Input-responsive, high yielding rice varieties and associated technologies responsible for the doubling of yields on irrigated lands in Asia have not suited the area of more than 40 million hectares of Asian rainfed lowland rice. These environments are home to some of the poorest rural populations in South and Southeast Asia, and the rice crops are subject to drought, prolonged submergence from uncontrolled flooding and nutrient deficiencies. Farmers grow unimproved varieties and these, combined with abiotic stresses and low inputs, result in grain yields often less than 2 t ha−1. The International Rice Research Institute (IRRI) and National Agricultural Research Systems (NARS) have recently joined to form the Rainfed Lowland Rice Research Consortium in order to identify, prioritize and execute strategic research that addresses critical yield and productivity constraints. Principal intervention points for achieving sustainable yield increases are in developing drought- and submergence-tolerant germplasm with good yield potential, improved nutrient management under stress conditions, water use-efficient crop establishment practices, and understanding farmers' approaches to risk management. Multidisciplinary teams of IRRI and NARS scientists execute research at sites selected across the region to represent the key sets of constraints.

This study investigated the responses of two wheat varieties, Huelquen (drought-tolerant) and Saitama 27 (drought-sensitive) to water stress induced by either covering the plants with rain shelters in the field, or by adding polyethylene glycol (PEG) to the nutrient solution of plants grown in a glasshouse. Preliminary work had determined the sensitivity of the two varieties to drought under field conditions. Water stress induced by PEG resulted in a decrease in root and shoot dry matter, a decrease in the dry-matter shoot to root ratio, a decrease in the relative water content, an increase in the number of stomata and epidermal cells per unit leaf area, an increase in the stomatal index, and an increase in free proline accumulation in both cultivars. The concentration of free proline increased to a greater extent in Huelquen than in Saitama 27 with increasing water stress. Increasing water stress decreased plant dry matter and relative water content, and increased the stomatal frequency, the number of epidermal cells per unit leaf area, and the stomatal index to a similar extent in both cultivars. Significant differences were found between the two varieties with regard to the chlorophyll stability indexes.

The results pointed out a positive influence of shallow soil cultivation and optimalized nitrogen dose on grain yield of winter barley. Two varieties (Luxor and Hanna) reacted significantly on shallow soil cultivation (disc tiller, var. C), where was reached a higher increase of yield from 0.26 to 0.31 t/ha in comparison to conventional cultivation. Babylone variety obtained the highest grain yield on conventional cultivation with an increase by 0.43 t/ha in comparison to shallow soil cultivation. Higher values of KEE from 4.51 to 5.8 and nutrient rate 1 : 0.65 : 1.66 were found out on variant with total dose of nitrogen 40 kg/ha. Multirowed Luxor variety reached an increase by 1.02 t/ha and by 1.18 t/ha compared to two-rowed varieties Hanna and Babylone. It is evident, from proportion of agrotechnical components, that an yield increase was influenced by variety (23%), cultivating methods (31%) and fertilisation (46%)

In the 1960s there were large-scale concerns about the world's ability to feed itself. However, widespread adoption of "green revolution" technology led to major increases in food-grain production. Between 1966 and 1990, the population of the densely populated low-income countries grew by 80%, but food production more than doubled. The technological advance that led to the dramatic achievements in world food production over the last 30 years was the development of high-yielding varieties of wheat and rice. These varieties are responsive to fertilizer inputs, are lodging resistant, and their yield potential is 2-3 times that of varieties available prior to the green revolution. In addition, these varieties have multiple resistance to diseases and insects and thus have yield stability. The development of irrigation facilities, the availability of inorganic fertilizers, and benign government policies have all facilitated the adoption of green-revolution technology. In the 1990s, the rate of growth in food-grain production has been lower than the rate of growth in population. If this trend is not reversed, serious food shortages will occur in the next century. To meet the challenge of feeding 8 billion people by 2020, we have to prepare now and develop the technology for raising farm productivity. We have to develop cereal cultivars with higher yield potential and greater yield stability. We must also develop strategies for integrated nutrient management, integrated pest management, and efficient utilization of water and soil resources.