Effects of irrigation frequency and water table depths on root growth and yield of tomato in a tropical soil
Abstract The effects of irrigation frequency and water table depths on tomato ( Lycopersicon esculentum , Mill, cv. Ife 1) root growth and fruit yield on a tropical soil were investigated. Tomato was grown at two water table depths (deep > 100 cm, and shallow Root length density, rooting depth, and fruit yield were generally higher at the deep than at the shallow water table location. At the deep water table location, the one-week irrigation frequency gave significantly higher root length density and fruit yield than the other irrigation frequencies. At the shallow water table location the two-week irrigation frequency gave higher fruit yield than the one- and three-week irrigation frequencies. There was a significant positive correlation between root length density and fruit yield.
Profile Storage and Deep Leaching of Soluble Nitrogen in a Savanna Soil under Continuous Cultivation and Fertilization for over Fifty Years in Nigeria
ABSTRACT Crop responses to nitrogen (N) fertilization reportedly depend on the storage of soluble N in the soil profile from the previous N-fertilization. We examined the profile storage of dissolved inorganic, DIN (NH4-N + NO3-N), and dissolved organic N, DON, in a savanna soil fertilized for over 50 years with farmyard manure, FYM, NPK-fertilizer, and their combination, FYM+NPK, along with a control plot and a native site, to determine the fertilization practice that best conserved soluble N from previous N-fertilization for subsequent cropping. The weight of total dissolved N (TDN) of 196 kg ha−1 in the soil profile under native vegetation was 3–4 times greater than 53 kg ha−1 in FYM+NPK-plot and the 64 and 65 kg ha−1 in the FYM-only and NPK-only, respectively. The NO3-N weight of 93 kg ha−1 under native vegetation was 5–9 times greater than the 11 kg ha−1 (NPK-only) to 19 kg ha−1 in the control. The DON weight of 45 kg ha−1 (native site) was 2–15 times greater than the 3 kg ha−1 in FYM+ NPK-plot and 29 kg ha−1 in NPK-only. Compartmentalizing the profile into the root zone (0–60 cm) and beyond the root zone (60–120 cm) indicated 76% NO3-N and 38% DON storage beyond the root zone under native vegetation due to leaching. Mean percentage changes in TDN in soil profiles under cultivation, using the native site as the reference, were – 83% for NO3-N, – 73% for DON, and – 29% for NH4-N, but the changes varied with fertilization practices.
On the fractionation of β-lactoglobulin and α-lactalbumin
Abstract Existing methods for the preparation of α-lactalbumin and β-lactoglobulin are examined critically. It is proposed that the most satisfactory method for the preparation of the whey protein fraction from bovine milk is (NH 4 ) 2 SO 4 fractionation. A number of new gentle procedures for the fractionation of the whey proteins are compared with some existing methods. The distribution of total protein at various stages is determined by total Kjeldahl nitrogen and the kind of protein by starch-gel electrophoresis. The effect of variables, such as pH, salt concentration and temperature on the separation of α-lactalbumin and serum albumin from β-lactoglobulin is studied. Differences in the behavior ( e.g. solubility) of genetic variants of β-lactoglobulin are noted. The solubility of each of the major whey proteins, under similar conditions to those used in the fractionation, is compared with its solubility in the whey protein mixture. The understanding gained of factors important in the fractionation is used in recommending new procedures for α-lactalbumin and β-lactoglobulin isolation.