บทคัดย่องานวิจัย

หมวดหมู่ : ฐานข้อมูลงานวิจัย

Tree nitrogen status and leaf canopy position influence postharvest nitrogen accumulation and efflux from pear leaves.

Sanchez, E. E.; Righetti, T. L.;

Journal of the American Society for Horticultural Science Year: 1990 Vol: 115 Issue: 6 Pages: 934-937 Ref: 26 ref.

1990

บทคัดย่อ

Tree nitrogen status and leaf canopy position influence postharvest nitrogen accumulation and efflux from pear leaves.

Six-year-old Comice pear trees on BA-29 quince rootstocks trained to a central leader were treated in May 1987 with 180 g N/tree using ammonium nitrate depleted in 15N. Another set of trees was treated with 120 g N/tree in spring 1988 using ammonium nitrate depleted in 15N and with 70 g N/tree using an unlabelled N source. In Aug., Oct. and Nov. 1988, leaves from central positions on current season shoots were sampled at 3 points from the periphery to the centre of the canopy. Total N content/cm2 of leaf area remained almost constant until Oct., even though N concentration declined as specific leaf weight increased. Furthermore, there was no substantial net change in either labelled or unlabelled N content of either group of trees until senescence began in Oct. Leaves from the canopy periphery contained higher levels of both reserve and newly-acquired N than did less-exposed leaves. Despite large differences in N content/cm2 in Oct., by Nov., leaves from trees of both high and low N status exported similar percentages of their total N. Irrespective of tree N status, the average proportion of total N exported to storage tissues from peripheral, intermediate and interior leaves was 71%, 61% and 52%, respectively. N export from leaves was influenced more by leaf position in the canopy than by tree nutritional status.