四倍体刺槐不同根龄幼林的生物量及叶片营养研究

Effects of root age on biomass and leaf nutrition in tetraploid Robinia pseudoacacia.

为了掌握四倍体刺槐根龄与生物量和叶片营养含量之间的变化规律,更好地指导实际生产,分别测定了四倍体刺槐不同根龄的生物量及叶片的营养含量。结果表明:四倍体刺槐不同根龄中当年生植株的株高、地径、茎叶比、总重和叶重均随根龄的增长而增加,3年根当年茎的总重和叶重分别达1 138和637 g;不同树龄的株高、总重、叶重和茎叶比也随着树龄的增长而增加,3年生树龄的总重为2 230 g,远高于3年根当年茎,但其叶重仅为603 g,稍低于3年根当年茎;当年生植株的叶片粗蛋白含量高达225.45 g/kg,极显著高于2年根当年茎、3年根当年茎、4年根3年茎和5年根4年茎(P<0.01),而后4个根龄之间叶片粗蛋白含量则无显著差异(P>0.05),且叶片粗蛋白含量均高于178.75 g/kg;根龄对钙含量的影响达到极显著水平(P<0.01),并且钙含量有随着根龄的增长而增加的趋势;不同根龄对四倍体刺槐叶片的粗脂肪、粗灰分、磷和单宁含量影响均不显著(P>0.05)。从生物量和营养综合考虑,四倍体刺槐饲料林定植当年不刈割,第2年开始刈割,进行矮林作业较好。

This study was conducted to assess the impact of root age on biomass and leaf nutrition in tetraploid Robinia pseudoacacia. Results indicated that plant height, base diameter, branch/leaf, gross weight and leaf weight of new sprout increased with root age. The total gross and leaf weight of the 3-year-old plant was 1 138 and 637 g at root age 3, respectively. The plant height, branch/leaf, gross weight and leaf weight increased with tree age, and the gross weight, which amounted to 2 230 g at tree age 3, was significantly higher than that of new sprouts with a root age of 3. But the leaf weight of the 3-year-old tree was only 603 g, lower than that of new sprouts with root age 3. In addition,the amount of crude protein in leaves of new sprout was 225.45 g/kg, which was significantly larger than those of new sprout in 2 years root age, new sprout in 3 years root age, threeyear-stem in 4 years root age and four-year-stem in 5 years root age （P 〈 0.01 ）. However, there were no significant differences among new sprout with a root age of 2, new sprout with root age 3, three-year-stem with root age 4 and four-year-stem in 5 years root age （ P 〉 0.05）. However, leaf crude protein of these plants was higher than 178.75 g/kg. The amount of Ca in leaves was significantly affected by root age （ P 〈 0.01） ,and increased with root age. The amount of ether extract, crude ash, P and tannin in leaves was not significantly affected by root age （ P 〉 0.05）. Overall, the data show that tetraploid R. pseudoacacia forage forest should be cut at age 2 and develop cultivated coppice to maximize biomass and plant nutrition.