施肥对旱地冬小麦近轴和远轴叶面气孔敏感性的影响

EFFECT OF FERTILIZATION ON SENSITIVITY OF ABAXIAL AND ADAXIAL STOMATAL RESISTANCE IN WINTER WHEAT LEAVES UNDER DRYLAND CONDITIONS

施肥降低旱地冬小麦的叶片水势。当作物体内出现水分胁迫时，冬小麦叶片两面气孔对施肥的反应有明显差异。远轴叶面气孔对施肥的反应比近轴叶面气孔敏感。旱地施肥以后，冬小麦远轴叶面气孔首先收缩，且收缩的程度比近轴叶面大，从而使远轴叶面气孔阻力与近轴叶面气孔阻力的比值（Ｒ＿（ａｂ）／Ｒ＿（ａｄ）增大。旱地施肥以后，远轴和近轴叶面气孔阻力均急剧增大，并且随肥力水平的提高（施肥量增加）而缓慢增大，二者皇直线关系发展趋势。旱地施肥对土壤水势有影响，但不论是提高还是降低土壤水势，均增大Ｒ＿（ａｂ）／Ｒ＿（ａｄ）。说明施肥确有增强旱地冬小麦远轴叶面气孔对环境因素变化敏感性的作用。２．４施肥对土壤水势的影响从表３可以看出，旱地施肥以后，在冬小麦的生育前期，土壤水势提高，这可能与施肥增强土壤接受降水和保水能力，减小地面蒸发，提高土壤含水量有关￣［３］。在冬小麦生育后期，土壤水势降低，这又与后期冬小麦叶面积较大，增加了土壤耗水量，使土壤含水量下降有关。这种现象和我们以前的试验结果￣［３］是一致的。由表３可见，不论施肥提高土壤水势还是降低土壤水势，均增大旱地冬小麦远轴和近轴叶面气孔阻力之比值，说明施肥确有此作用。这种现象也表明施肥提高了?

tudies on the response of stomatal resistance of plants to fertilizationunder dryland conditions can provide important insight as to the regulationof water use by means of soil fertility management. During the growingseason, we measured the stomatal resistance on both sides of the winter wheatleaves with Li-1600 Steady State Porometer at different fertilization levels.The application of N and P fertilizers(Urea,Calcium superphosphate andrapeseed cake)decreased the leaf water potential of winter wheat Fertilizationresulted in apparently different responses of abaxial and adaxial stomatalresistance to the changes of environmental factors when there was a waterdeficit in crop plants.The abaxial stomatal resistance was more responsive tofertilization than adaxial stomatal resistance. The abaxial stomatal resistanceincreased more rapidly and to a larger extent than adaxial stomatal resistancewith increasing fertilization levels.Both abaxial and adaxial stomatal resista-nces increased sharply in an immediate response to fertilization,After that,there was a slow but linear increase of stomatal resistances with the increaseof fertinzation lvds.Our results also showed that the ratio of abaxial toadaxial stomatal resistance(R_(ab)/R_(ad))increased linearly with increasingfertilizer-application levels,regardless of the water potentials that weregreatly affected by fertilization. We concluded that,under dryland condi-tions,fertilization had effect on the improvement of the sensitivity of abaxialstomatal resistance to the changes of environmental factors.