为探讨不同灌溉方式对紫花苜蓿(Medicago sativa)生长、水分利用效率及产量的影响,通过田间试验研究了地下滴灌(SDI)、畦灌(BI)、喷灌(SI)和不灌溉处理(CK)4种灌溉方式下苜蓿生长的变化.结果表明:各处理间,SDI的土壤含水率在试验期间最高,且SDI的苜蓿株高、分枝数、单株叶面积及单株干重均显著高于BI,SI和CK;SDI两茬的产量分别为4815.87和4300.41kg·hm-2,与BI,SI和CK相比,第2茬分别提高了10.56％,14.92％和95.26％,第3茬分别提高了13.64％,23.60％和120.85％,均达到显著水平(P＜0.05);SDI两茬的水分利用效率分别为2.66和2.50 kg·m-3,较BI和SI处理,第2茬分别提高了17.70％和21.46％,第3茬提高了20.77％和34.41％,均达到显著水平(P＜0.05).因此,从苜蓿生长、产量及水分利用效率角度考虑,地下滴灌是西北旱区最为适宜的灌溉方式.

2014年6月初至7月下旬,在西北旱区生长第三年紫花苜蓿的第二茬草生育期间,设置地下滴灌(SDI)、喷灌(SI)、畦灌(BI)和试验期间不灌溉(CK)四种灌溉方式进行对比试验,研究不同灌溉方式对紫花苜蓿生长、光合特性及产草量的影响.结果表明:不同灌溉方式影响土壤水分含量,SDI的土壤含水率最高,CK最低;各处理的净光合速率和蒸腾速率均呈现“午休现象”,CK最明显;SDI的日均净光合速率、蒸腾速率、叶片水分利用效率及光能利用效率均显著(P＜0.05)大于BI、SI和CK,BI与SI处理差异不显著;相比其他三种处理方式,SDI处理能有效提高苜蓿株高、茎粗、分枝数、单株重和产草量,SDI处理干草产量比BI、SI处理分别提高了10.56％和14.92％,差异显著(P＜0.05).

通过大田喷灌试验,研究了苜蓿生长适宜的灌水量.结果表明,喷灌条件下不同灌水处理苜蓿的生长、产量、水分利用效率与耗水量有极高的相关性(R2＞0.97);随着灌水量增加,苜蓿生长越好,产量越高,当灌水量大于140 mm时,苜蓿产量不再随灌水量增加而增加;苜蓿的水分利用效率随着耗水量的增加先增加后降低,灌水利用效率随耗水量的增加降低,差异均显著(P＜0.05).该研究揭示喷灌条件下140 mm的灌水量不仅可以使石羊河流域苜蓿增产还可以节约水资源.

Subsurface drip irrigation (SDI) and regulated deficit irrigation(RDI)are two of the most water-saving irrigation technologies nowadays. In order to study effects of regulated deficit irrigation on forage water consumption, hay yield and quality of alfalfa under subsurface drip irrigation, a field experiment was carried out in 2012 at Shiyang River Drainage Basin, northwest of China. Alfalfa used for the experiment is the second cutting of the establishment year, and the cutting is separated into 3 periods, including pre-branching period, branching period and squaring period. There are seven irrigation treatments in the experiment design. Four of the seven treatments are regulated in whole growth period, lower irrigation limits respectively 70% FC (field capacity)、60%FC (field capacity)、50%FC (field capacity)、40%FC (field capacity), and three are regulated in different growth periods, lower irrigation limits of pre-branching period, branching period and squaring period of different treatment respectively (50%, 50%, 70%)FC, (60%, 60%, 70%)FC, (70%, 70%, 50%)FC. When the soil water content arrives to the designed lower irrigation limit, each plot starts to irrigate. Irrigation amount is 20mm every time. According to these treatments, the effect on water consumption, hay yield and quality of alfalfa of regulated deficit irrigation (RDI) under subsurface drip irrigation(SDI) are studied. The results show with the deterioration of the water deficit degree, alfalfa yield, water consumption, stem/leaf ratio and yield of crude protein (CP) decrease while WUE (water use efficiency) and content of the crude protein (CP) increase, and 60%FC is a critical value. When the lower irrigation limits are higher than 60%FC, hay yield of alfalfa decrease non-significantly, however, when lower than 60%FC, hay yield decrease significantly. While RDI (regulated deficit irrigation) is taken in the whole growth period, squaring period>branching period>pre-branching period appears in water consumption rate during different periods of alfalfa. And this law is more and more significant with the increasing of the water deficit degree. When RDI (regulated deficit irrigation) is taken in branching period, water consumption rate of alfalfa have apparent compensation effect after sufficient irrigation in squaring period. Compared with regulating deficit in squaring period, taking RDI (regulated deficit irrigation) in pre-branching and branching period is more conducive to improve alfalfa quality by reducing stem/leaf ratio and improving content of crude protein (CP) and yield of crude protein. When lower irrigation limits of pre-branching period, branching period and squaring period are 60%FC, 60%FC and 70%FC respectively, alfalfa has the highest crude protein yield (846.11kg/hm2). This study reveals the effects of RDI on water consumption, yield and quality of alfalfa under SDI and provides an experimental base of high quality, high yield and water saving in alfalfa industry in arid areas.