Reduced water consumption of dormant-seeded sugar beet in a semiarid climate
Dormant seeding refers to sowing spring crop species in fall. In the spring, seedlings start growing and the crop is established before spring sowing is normally completed. A dormant-seeded crop can establish quickly in spring and may escape from early season drought. A study was conducted to compare performances of dormant seeding with early and late spring seeding of sugar beet. Field experiments were carried out in the Khorasn province (NE of Iran) in 2002 and 2003 by growing a bolting resistant variety (BR1). The experiment consisted of a randomized complete block design with four replications. Dormant seeding was subjected to six irrigation treatments in addition to an early and late spring seeding. The first irrigation was applied 0, 10, 20, 30, 40 and 50 days after 60% soil moisture depletion. After harvest, root yield, sugar concentration, white sugar yield, and non-sugar components of the root samples were measured and analyzed. The results of the dormant seeding showed that root yield of sugar beet decreased with increasing delay of irrigation at the early stages of plant growth. High white sugar yield was obtained at dormant seeding without irrigation delay compared to the early seeding. No significant differences were observed for white sugar yield until three and five water withholdings in 2002 and 2003, respectively. In the second year of the experiment (2003), a relatively cold winter induced about 4.5% bolters and reduced plant population with 33% compared to the early and late spring sowing treatments. In general, white sugar yield produced in response to specific irrigation amounts for dormant-seeded treatments was higher compared to early and late seeding. However, dormant seeding cannot yet be recommended as a comprehensive agricultural practice for sugar beet and, therefore, further investigations are required to improve the quality of the beet by both agronomic techniques and new improved varieties.
Abiotic Stress in Sugar Beet
The production of sugar beet (Beta vulgaris L.) is often limited by environmental conditions that cause decreased rates of photosynthesis, canopy expansion, root growth and sucrose accumulation. These conditions include insufficient water, heat, freezing temperatures and salinity. Compared to other crops such as cereals, harvestable sugar yields can be obtained even under harsh growing conditions. However, the realization of maximum production efficiency and profits demands that varieties must show less susceptibility to abiotic stress and improved yield stability across a range of environments. This is particularly urgent in light of climate change models that predict hotter and drier growing conditions for many areas. There are only limited breeding efforts to improve the tolerance of new varieties to these stresses, in part because the mechanisms of tolerance are poorly understood and methods to screen germplasm for resistant genotypes have not been fully developed. Fortunately, there appears to be significant genotypic diversity for tolerance to drought, heat, cold and salinity within sugar beet germplasm, so opportunities exist for varietal improvements. Developments in irrigation technologies and innovations in agronomy and soil management techniques may also contribute to improved yields of crops faced with abiotic stresses.
Assessment of some agro-technological parameters of cactus pear fruit ( Opuntia ficus-indica Mill . ) in Morocco cultivars
Cactaceae had always attracted attention by their strange shapes and important adaptability supporting extreme conditions. For this reasons, Fruit traits were measured on 13 cultivars growing in different locations in Morocco. Results show significant differences between the cultivars. The source of this variation was probably genetic without excluding the geographic effects. The Tamri, Berkan, Ait Baha cultivars showed small fruit dimensions and weight. In contrast, Sidi-Ifni M, Nador, Mohammedia and Ben Guerir were greater than 100 g by fruit. Sidi-Ifni M, Hoceima, Mohammedia and Nador, although larger, contained few seeds, about 200 seeds per fruit; while Tamri, Ait Baha, Safi, Meknes and Tafraout contained over than 230 seeds per fruit. High levels of juice about 62 ml/100 g pulp were obtained with Sidi-Ifni M, Nador, Mohammedia and Ben Guerir cultivars. Total sugars of the 13 cultivars were quite similar and pH was low in Tamri and close to neutrality in the rest of cultivars. Therefore, oil extracted from Opuntia ficus-indica seeds constituted 13.6% of the whole seed. Thin-layer chromatography in conjunction with gas-liquid chromatography-mass spectrometry revealed a relatively high degree of unsaturation, 83.32% and 16% for saturated fatty acid, with a linoleic acid content of 63.66% followed by oleic 18.34%, palmitic 12.84% and stearic acid 2.81%. Based on these results, O. ficus-indica seed oil appears to be a good potential source of edible oil for human and (or) animal consumption. Our investigation describes that Tamri and Tafraout cultivars are not really a commercial viable fruit due to low total soluble solids value and highest seeds number per fruit. Against Mohammedia, Sidi Ifni M and Nador cultivars proved to have the highest fruit weight, very good total soluble solids value and low number of seeds, these cultivars can therefore be planted for both fruit production and for harvesting of cladodes for animal feed.