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.
Woburn irrigation, 1960–8:IV. Design and interpretation
SUMMARY Results are given for a second period of 9 years, 6 on the pattern of 1951–9, with the last 3 years used for ad hoc management experiments. The meteorological specification of a year of ‘irrigation need’ was satisfied in 4 years: there were good responses in 5 years. During the first 6 years, out of twenty-four sets of crop yields (from eight different crops), very good responses were obtained on nine, good responses on eight, and zero or very slightly negative responses on the other seven. A general theory of the inter-relationships of growth and water, and of growth and radiation, leads to an expression k = 39ε t ha−1 cm−1, as the maximum possible response to irrigation in terms of total dry matter produced, where ɛ is the fraction of solar radiation fixed by the crop (ɛ has a range 50–100 × 10−4 for good to very good farming) when irrigation is needed. The ‘need’ is defined through Y = k(ET + De − Dm), where Y is the yield, ET is the total potential evaporation, De is a limiting deficit up to which there is no check to growth, and beyond there is no growth, and Dm is the maximum deficit experienced by the crop at the time of measuring Y. The agronomic object of the experiments is to determine De, i.e. what reserve of soil water can be used by the crop before irrigation is necessary.
Novel method for the determination of the methoxyl content in lignin by headspace gas chromatography.
The paper reports on a headspace gas chromatographic (HS-GC) method for the determination of methoxyl in lignin. The method involves the quantitive cleavage of methoxyl with hydroiodic acid (HI) to form methyl iodide in a closed headspace sample vial at 130 °C for 30 min. After HI has been added, the sample is neutralized by injecting a sodium hydroxide solution; the methyl iodide in the vial was determined by HS-GC using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD < 0.69%) and accuracy (RSD < 3.5%) for the quantification of methoxyl content in lignin. The present method is simple and accurate and can be used for the efficient determination of methoxy1 content in lignin and related materials.