Effects of Different Soil Matric Potential at Different Growth Stages on Physiological Characteristics and Yield of Spring Sown Carthamus Tinctorius L. under Drip Irrigation Condition

Abstract

【Objective】 The purpose of this paper is to explore the effects of soil matrix potential (SMP) regulation at different growth stages on the physiological characteristics and yield of spring sown Carthamus tinctorius L. 【Method】 Three SMP thresholds, i.e.,W1(-20 kPa),W2(-30 kPa) and W3(-40 kPa) were set at the elongation period + branching period (A), and elongation period + branching period + flowering period (B), with SMP of -50 kPa at 0.2 m soil depth below the emitter as the CK. At the flowering period, photosynthetic parameters such as the net photosynthetic rate, stomatal conductance, transpiration rate and intercellular CO2 concentration of Carthamus tinctorius L. leaves were measured. At the same time, the physiological indexes such as chlorophyll, soluble protein, malondialdehyde and relative conductivity of Carthamus tinctorius L. leaves were measured. The flower yield of Carthamus tinctorius L. were counted after harvest. 【Result】 The net photosynthetic rate, stomatal conductance, transpiration rate and total chlorophyll content of W1B and W2B treatments reached the maximum, in which W1B increased by 37.1%, 60.0%, 44.6% and 34.1% respectively compared with CK, and W2B increased by 39.6%, 57.7%, 42.8% and 38.8% respectively compared with CK; The soluble protein content of W1B treatment was the largest, which was 43.8% higher than that of CK. The malondialdehyde content and relative conductivity of W1B and W2B were the lowest. The malondialdehyde content and relative conductivity of W1B were 25.0% and 19.0% lower than CK, and W2B was 20.8% and 18.3% lower than CK, respectively; The flower yields of W1B and W2B were the highest, which were 65.8% and 57.1% higher than CK respectively. 【Conclusion】 W1B and W2B treatments had the best photosynthetic characteristics, the highest total chlorophyll content, the lowest malondialdehyde content and relative conductivity, and the highest flower yield. Therefore, maintaining the lower limit of soil matrix potential at -20 kPa or -30 kPa at spring sown Carthamus tinctorius L. elongation period, branching period and flowering period has the highest yield potential. In consideration of water conservation, it is recommended to maintain the lower limit of soil matrix potential at -30 kPa.

Keywords

• soil matric potential
• carthamus tinctorius l.
• physiological characteristics
• yield