水氮梯度对饲用甜高粱生长和水分利用效率的影响

马仁诗; 蒋丛泽; 受娜; 高玮; 沈禹颖; 杨宪龙

doi:10.11674/zwyf.2022250

摘要:

目的探究不同灌溉量和施氮水平对饲用甜高粱生长特性、单株耗水规律以及水分利用效率的影响，为确定饲用甜高粱适宜种植密度、优化水氮管理措施以及提高栽培生产潜力提供理论支撑。

方法在温室条件下进行二因素三水平随机区组试验，供试饲用甜高粱品种为‘大力士’。设置了3个灌溉量，分别为达到田间持水量的30%～50% (I1)、50%～70% (I2)、70%～90% (I3)；设置了3个施氮水平，分别为0 kg/hm² (N0)、200 kg/hm² (N1)、400 kg/hm² (N2)。在饲用甜高粱拔节期取样，测定甜高粱株高、茎粗、鲜重与干重。同时，采用自动称重式蒸渗仪测定单株耗水动态，计算了干物质水分利用效率。

结果 1)增加灌溉量显著增加了饲用甜高粱株高和茎粗，与I1相比，I2、I3灌溉量下甜高粱株高分别提高了20.0%和34.5%，茎粗分别增加了18.0%和36.6%。施氮对株高和茎粗无显著影响。2)增加灌溉量显著提高甜高粱植株茎、叶及地上部鲜重和干重，施氮水平仅显著影响叶的鲜重和茎的干重。与I1相比，I2、I3灌溉量下地上部整株鲜重分别提高158.1%、290.1%，干重分别提高84.8%、139.3%。与N0相比，N1、N2施氮量下叶的鲜重分别提高7.6%、4.6%，茎的干重分别降低8.5%、10.4%。I1灌溉量下茎叶比<1，I2和I3灌溉量下茎叶比>1，随着灌溉量增加，饲用甜高粱茎叶比显著增加。在I1、I3灌溉量下，茎叶比随着施氮量的增加而降低。3)随着灌溉量的增加，甜高粱单株耗水量显著增加，而水分利用效率则显著下降。与I1相比，I2、I3灌溉量下累积耗水量分别提高了101.3%、178.9%，水分利用效率分别降低了8.0%、13.9%。施氮对甜高粱单株累积耗水量及水分利用效率均无显著影响。

结论灌溉量显著影响着甜高粱的生长、干物质量的积累以及干物质向茎秆的分配，过高的灌水量会增加饲用甜高粱的耗水量，降低水分利用效率。氮素对甜高粱的生长未显现出促进作用，高施氮量还会增加干物质在叶片中的分配。因此，适度灌溉并施用少量氮肥可能更适合甜高粱的饲用品质和高水分利用效率。

Abstract:

Objectives This study investigates the effects of different irrigation levels and nitrogen (N) application rates on the growth, water consumption, and water use efficiency of forage sweet sorghum (Sorghum bicolor L. Moench) to provide theoretical and technological support for the efficient cultivation of forage sweet sorghum.

Methods A pot experiment was conducted under greenhouse conditions using the sweet sorghum cultivar ‘Hunnigreen’ as test material. The three irrigation rates employed were maintaining soil moisture content at 30%～50% (I1), 50%～70% (I2), and 70%～90% (I3) of the field capacity. The three N application rates were 0 kg/hm² (N0), 200 kg/hm² (N1), and 400 kg/hm² (N2), giving a total of 9 treatments. The soil moisture and plant water consumption were automatically monitored by a soil moisture sensor and auto-weighed lysimeters, respectively. The plant height and stem diameter were investigated 30, 40, 50, 65, and 85 days after emergence. The fresh and dry weights of plant were investigated 85 days after the emergence of forage sweet sorghum.

Results Compared with I1, I2 and I3 increased plant height by 20.0% and 34.5% and stem diameter by 18.0% and 36.6%, respectively. N application rate had no significant effect (P>0.05) on plant height and stem diameter. Increasing irrigation (P<0.05) promoted the fresh weight and dry weight of stems, leaves, and whole plants, while increasing N application rate only affected the fresh leaf weight and stem dry weight. Compared with I1, I2 and I3 increased the whole plant fresh weight by 158.1% and 290.1% and dry weight by 84.8% and 139.3%, respectively. Compared with N0, N1 and N2 increased the fresh leaf weight by 7.6% and 4.6% and decreased dry stem weight by 8.5% and 10.4%. The stem-leaf ratio was <1 under I1, >1 under I2 and I3, and higher under I3 than I2. Under I1 and I3, the stem-leaf ratio decreased with an increase in the N application rate. Increasing irrigation (P<0.05) increased the individual plant water consumption and decreased the water use efficiency. Compared with I1, I2 and I3 increased the cumulative water consumption by 101.3% and 178.9% and decreased the water use efficiency by 8.0% and 13.9%, respectively. N application rate had no significant effect (P<0.05) on cumulative water consumption and dry matter water use efficiency.

Conclusions The growth, water consumption, and dry matter water use efficiency of forage sweet sorghum were highly affected by irrigation level and slightly impacted by nitrogen application rate. The increase in irrigation level promoted the growth of plant height and stem diameter, the accumulation of dry matter and the dry matter allocation to stem, and increased the water consumption, but decreased water use efficiency. Therefore, moderate irrigation and low N fertilizer application rate are promising for efficient forage sweet sorghum production and water use efficiency.

水氮梯度对饲用甜高粱生长和水分利用效率的影响

Effects of water and nitrogen gradients on growth and water use efficiency of forage sweet sorghum