| It is very important to elucidate the collectable amounts and the nutrient status in different layers of wheat canopy to better utilize wheat straw. In this study, by using two wheat cultivars(Triticum aestivum L. cv Ninmai 9 & cv Yumai 34), field experiments with five treatments(nitrogen rate of 0, 75, 150, 225 and 300 kg·hm-2) were conducted in Nanjing during 2011 and 2012. The experiment was designed as a randomized complete block using three replications and each replication was sampled at maturity. After cutting off the spike, the plant shoots were divided into four sections averagely to investigate the vertical distribution of dry matter, nitrogen(N), phosphorus(P) and potassium(K) in different positions of the wheat canopy, and each section was separated into leaves and culms. The results showed that the grain yield reached the highest in the treatment 225 kg·hm-2. There were significant vertical differences on dry matter and nutrient accumulation in the wheat canopy layers from top to root. The total accumulation amount of dry matter, N, P and K in the straw increased with the increasing of nitrogen rate. In each treatment, the dry matter weight increased firstly and decreased afterwards in the four layers of the wheat canopy from top to root, N and P accumulation decreased, while K accumulation increased. And in the stem-sheath, dry matter and K accumulation increased, and N and P accumulation reached the highest in the second and the third layer. There were significant linear relationships between grain yield and the accumulation of dry matter, N, P and K in different layers of leaf and sheath. The results indicated that in the highest grain yield case, when the wheat straw was returned to the field totally, the contributions of N, P and K in wheat straw to that in soil pool were 3.7, 2.8 and 9.9 kg·hm-2, respectively, and when only the straw stubble(leaf and stem-sheath in the fourth layer + glume) was returned to the field, the proportions of returned to the total in straw were 40, 50 and 40%, respectively. |
基本信息
