ALBERT

Description: SUMMARYThe response of low glucosinolate, low erucic acid (double low) cultivars of oilseed rape to spring nitrogen application was examined at Cockle Park, Northumberland in three successive seasons (1987–90). Seed yield and protein content increased in response to increasing nitrogen application. In each season over 85% of the maximum recorded yield was obtained with an application of 150 kg N/ha. In the absence of spring nitrogen, seed yield varied considerably over the three seasons. The variation in seed yield and protein content between 1987/88 and 1988/89 can partly be explained by differences in the availability of soil nitrogen in the different seasons. Seed glucosinolate concentration was significantly increased withnitrogen applications between 0 and 150 kg/ha. Increasing nitrogen beyond 150 kg/ha hadlittle or no effect on seed glucosinolate concentration. The results are examined with reference to the varying effects of increasing nitrogen application rates on seed glucosinolate concentrations reported previously.

Description: SUMMARYField experiments were conducted to test the seed yield responses of winter oilseed rape (Brassica napus L., cvs Libravo or Falcon) to the addition of different rates of S fertilizer, at three N application rates, on a sandy loam at Woburn, Bedfordshire, in 1990/91, 1991/92 and 1993/94. Large increases in seed yields, ranging from 0·7 to 1·6 t/ha, or 42–267% on a relative scale, were obtained in response to the application of 40 kg S/ha with 180 and 230 kg N/ha treatments. The effects of S were highly significant in 1991/92 (P 〈 0·01) and 1993/94 (P 〈 0·001) and close to significant (P = 0·053) in 1990/91. The yield benefits were obtained mainly from the application of the first 10 kg S/ha and further yield increases were unlikely above 40 kg S/ha. Increasing N application from 180 to 230 kg/ha decreased seed yield in 1990/91 and 1993/94, when no S was applied. In contrast, seed yield was not increased by S at zero or low (50 or 100 kg/ha) N rates. The interactions between N and S on seed yield were significant (P 〈 0·05) in 1990/91 but not in the other two seasons. Application of S also increased seed oil content in 1993/94, when the degree of S deficiency was particularly severe. With an application of 230 kg N/ha, the crops took up 5–22 kg S/ha at maturity when no S was applied and 26–51 kg S/ha when 40 kg S/ha was applied. The utilization efficiency of the fertilizer S ranged from 50 to 73% in the three seasons. Although the concentrations of total N in plants were largely unaffected by S treatments, large amounts of NO3-N accumulated in the leaves of S-deficient plants in 1993/94. This indicates that N metabolism was disrupted by S deficiency. The concentrations of S and the N: S ratios in different tissues and the whole plant changed considerably with time. The concentration of S in leaves at early flowering was found to be the best index in predicting S deficiency in terms of seed yield, and a critical value of 3·8 mg/g was obtained. In comparison, the N: S ratio in leaves at early flowering was a much poorer predictor of S deficiency.

Description: Glutathione S-transferases (EC 2.5.1.18, GSTs) are a family of multifunctional enzymes that play important roles in oxidative stress resistance. In the present study, it was investigated whether expressing Suaeda salsa GST in transgenic rice (Oryza sativa L. cv Zhonghua No.11) could confer resistance to abiotic stress. Several types of stress, including salt, paraquat and chilling were applied. It was shown that following paraquat applications, the activity of GST, catalase (CAT, EC 1.11.1.6) and superoxide dismutase (SOD, EC 1.15.1.1) increased significantly in the GST transgenic plants compared with non-transgenics. Following NaCl and chilling stresses, only SOD and CAT activities increased markedly in the transgenics and there were no significant differences in GST expression between transgenics and non-transgenics. Moreover, in stressed plants, the generation of H2O2 and Malon dialdehyde decreased more in the transgenics than in non-transgenics. These results imply that expression of the Suaeda salsa GST in transgenic rice could enhance abiotic stress tolerance and the antioxidant enzymes of the active oxygen-scavenging system might play integral roles in the protection of plants from oxidative stress.

Description: SUMMARYSix field experiments were carried out in eastern England between 2003 and 2005 to test the effect of sulphur (S) fertilizer on the yield of sugar beet (Beta vulgaris L.). The experiments were undertaken at sites where there had previously been a positive response to S in other crops or where no S-containing materials had been applied for more than 20 years. No individual experiment produced a significant positive response to S application, but the treatments that received no S fertilizer produced the smallest yield in five of the six experiments. Analysis across years using restricted maximum likelihood (REML) procedures showed that there was a positive and significant sugar yield response in beet of 0·56 t/ha where positive responses had previously been recorded in other crops grown on these loamy sand soils. Beet crops grown in soils of this type should receive S fertilizer that can be applied conveniently as sufficient ammonium sulphate to supply the first dressing of N.