Maize leaf functional responses to drought episode and rewatering

Abstract

<jats:title>Abstract</jats:title><jats:p>Effects of crop growth and physiological activity to drought and irrigation regimes have been extensively studied; however, the responses of plant growth, morphological and photosynthetic behaviors to drought episodes and thereafter rewatering receive a less attention. This field experiment was carried out directly <jats:italic>in situ</jats:italic> at an agricultural ecosystem research station during 2015-2016, in a northeastern China, on the renowned northeastern maize production belt, where is being threatened by severe drought. A field automatic rain-shelter was used, and five irrigation regimes including control, four drought episodes, and rewatering treatments were established. The chlorophyll contents (SPAD values), light-saturated photosynthetic rate (<jats:italic>A</jats:italic><jats:sub>sat</jats:sub>), and photosystem II actual quantum yield (Φ<jats:sub>PSII</jats:sub>), maximum quantum yield (<jats:italic>F</jats:italic><jats:sub>v</jats:sub>′/<jats:italic>F</jats:italic><jats:sub>m</jats:sub>′) decreased at lower leaf positions and with plant development. Episodic drought effects on plant growth, leaf morphological traits and photosynthetic processes at both vegetative and reproductive stages were severely remarked, particularly at late development stage and with longer drought duration. The recovery of leaf functional traits of the plants experienced historical-drought following re-irrigating was not fully restored to the level of the plants subjected to ample and normal water status; and the strength of recovery was proportional to the persistence of pre-drought episodes. The relationship of <jats:italic>A</jats:italic><jats:sub>sat</jats:sub> with SPAD depends on water status and plant development. A principal component analysis can well denote the change patterns in responses to water status treatments with plant development. The results may give an insight into how to understand the maize traits’ responses to drought episode and rewatering, and this also might assist the drought-stricken crops to cope with future climatic change.</jats:p>

Differential responses of maize yield to drought at vegetative and reproductive stages

“…The reduction in DM from short-term water stress at the beginning of the intensive vegetative growth stage was mainly caused by the reduction in plant height and leaf size and delay in leaf tip emergence (Çakir 2004). Some results from the same experiment showed that PD effects plant growth, leaf morphological traits and photosynthetic processes at vegetative and reproductive stages and leaf function traits of the plants experienced PD cannot fully restored compared to CK (Song et al 2018), which led to the decrease in the total biomass.…”

“…Weighing method was used to measure gravimetric soil water content (%) to a depth of 50 cm (every 6-8 days since early June in 2015 and early July in 2016 until the end of August). The detail of the method can be referred to Song et al (2018). We used soil relative extractable water (θ r , equation 1) to represent the soil available water conditions.…”