不同供钾水平对西瓜幼苗生长和根系形态的影响

通过盆栽试验,研究5个供钾水平(0、60 kg.hm 2、240 kg.hm 2、500 kg.hm 2和700 kg.hm 2)下西瓜苗期生长指标和根系形态参数的变化。结果显示:240 kg.hm 2钾浓度下,西瓜幼苗茎鲜重、叶鲜重、茎干重、叶干重、子叶面积、茎粗、株高、根长、比根长、表面积、根体积、根尖数和根平均直径分别比不施钾处理增长46.05%、31.31%、57.56%、29.87%、2.92%、12.71%、37.18%、67.23%、64.00%、64.03%、58.88%、154.11%和6.25%。700 kg.hm 2钾浓度下,西瓜幼苗茎鲜重、叶鲜重、茎干重、叶干重、子叶面积、茎粗和株高比240kg.hm 2钾浓度处理分别降低40.24%、25.31%、36.90%、23.08%、31.09%、9.81%和41.44%。700 kg.hm 2钾肥处理对西瓜幼苗根系生长的抑制作用不明显。所有处理的西瓜幼苗直径≤1.0 mm的根长占总量的90%以上,直径≤0.5 mm的根尖数占总量的98%以上;直径≤2.0 mm的比根长、根体积和根表面积占总量的50%以上;钾素对西瓜幼苗直径≤2.0 mm、2.5 mm<直径≤3.0 mm、3.5 mm<直径≤4.0 mm的根长、比根长、根表面积、根体积影响最明显。由于细根的吸收活力比较强,而西瓜细根所占比例最大,因此缺钾条件下,西瓜幼苗钾营养状况受到的影响较根系生长受到的影响更为严重。适宜的钾浓度有利于西瓜幼苗的生长,提高幼苗的生长质量,促进根系的生长发育,而不施钾和高钾处理会抑制幼苗的生长,但高钾对根系生长的抑制作用不明显。在本试验条件下,综合考虑经济因素,240 kg.hm 2钾肥施用量对西瓜幼苗生长和根系形态建成效果最明显。

Effects of different potassium nutrition on growth and rootmorphological traits of watermelon seedling

The study was carried out by a pot experiment supplied with five K levels [0(K0),60 kg·hm 2(K1),240 kg·hm 2(K2),500 kg·hm 2(K3),700 kg·hm 2(K4)] to probe into effects of different application of potassium fertilizer on watermelon seedling growth and root morphology traits.Results indicated that under 240 kg·hm 2 potassium application,stem fresh weight,leaf fresh weight,stem dry weight,leaf dry weight,leaf area,stem diameter,plant height,total root length,specific root length,surface area,root volume,root tips and root average diameter were 46.05%,31.31%,57.56%,29.87%,2.92%,12.71%,37.18%,67.23%,64.00%,64.03%,58.88%,154.11% and 6.25% higher than those under no potassium application.Under 700 kg·hm 2 potassium application,stem fresh weight,leaf fresh weight,stem dry weight,leaf dry weight,leaf area,stem diameter and plant height were 40.24%,25.31%,36.90%,23.08%,31.09%,9.81% and 41.44% lower than those under 240 kg·hm 2 potassium application.The effect of 700 kg·hm 2 potassium application on root morphological traits were not obvious.Additionally,the root length in root diameter ≤ 1.0 mm was above 90%,the root tips in root diameter range ≤ 0.5 mm was above 98%,specific root length,surface area and root volume in root diameter ≤ 2.0 mm was above 50% of total amount,respectively.Root length,specific root length,surface area and root volume of root diameter ≤ 2.0 mm,2.5 mm < diameter ≤ 3.0 mm,3.5 mm < diameter ≤ 4.0 mm were significant affected by K level.Morphological traits were determined by specific root length,surface area,root volume and tips in root diameter ≤ 2.0 mm.Because of relatively stronger absorption and the largest proportion of fine roots,the impact of potassium deficit on potassium nutrition of watermelon seedling was more serious than that on roots growth.Appropriate potassium concentration was beneficial to the growth of watermelon seedlings,it could improve the quality of seedlings growth,root growth and development.No potassium application and high potassium restrained the growth of seedlings,but the inhibition of high potassium on the root growth was not obvious.Under this experimental condition,the 240 kg·hm 2 potassium application treatment was the best.