The physical properties, lignin distribution, chemical composition of fibers and gas exchange rate of kenaf (Hibiscus cannabinus L.) varieties under prolonged water deficiency

Abstract

The fundamental characteristics and physical properties of kenaf (Hibiscus cannabinus L.) fibers cultivated and subjected to three different water frequencies in Universiti Putra Malaysia, were analyzed. For deep analysis, which includes micro-scale viewing for identification of kenaf cell wall structure, fibers were viewed in order to study the physical characteristics, anatomy, and lignin distribution. The chemical composition was determined considering Technical Association of Pulp and Paper Industry (TAPPI) methods. Water stress treatments were imposed on the plants four weeks after germination when they had attained more than four leaves: daily watering based on soil field capacity (100% ER; well watered), water stress imposition 1 month after seedling establishment completion (1MAS) and water stress imposition at flowering stage (AFS). Each water treatment was replicated three times in a randomized complete block design (RCBD) in split plot arrangement with water treatments as the main plots and the varieties as the sub-plots; irrigation system was applied for the purpose. Different water treatments and different varieties at the end of experimental period had significant impact on fiber dimensions and physiological attributes. Fiber quality attributes, gas exchange rate and growth parameters were affected in negative way when all varieties had been subjected to water stress regardless of time of stress imposition.

Determination of Diurnal Leaf Gas Exchange for Drip-Irrigated Kenaf Plant in Sub-Humid Climatic Conditions

“…The minimum values were observed in the morning in 2019 and in the evening in 2020, which are the hours when the arrival angles of the sun rays on the plants are more oblique. When the studies including seasonal measurements are examined, it is seen that the A values of the fully irrigated kenaf plant can reach up to 25-30 μmol CO 2 m -2 s -1 [11,12]. In parallel with the obtained values, [13] reported that the maximum net photosynthesis rate for Tainung 2 cv.…”

“…The measurement time has been found to influence gs [39]. [12] stated that the values measured during the season in fully irrigated kenaf plants reached 0.95 mol H 2 O m -2 s -1 . [13] declared that the highest gs values reached during the day were 1.3 mol H 2 O m -2 s -1 and 1.75 mol H 2 O m -2 s -1 for Tainung 2 and Everglades 41 cultivars, respectively.…”

“…(10) g bw is boundary layer conductivity to water vapor (mol H 2 O m -2 s -1 ) and depends on whether there are stomata on one or both sides of the leaf. The k f value is a factor based on the estimated K fraction of stomatal conductivity and calculated as, (11) Net Photosynthesis Rate sa = u i c i -u o c o (12) Equation ( 12) is the mass balance approximation of CO 2 existing in an open system. Assimilation rate (mol CO 2 m -2 s -1 ) shows by a, input and output mol fractions (mol CO 2 mol air -1 ) of CO 2 show by c i and c o .…”

“…Leaf gas exchange is one of the main factors that determine the yield of the plant and give information about its development [10]. Several studies were carried out to determine the seasonal changes in the net photosynthesis rate (A), stomatal conductivity (gs), intercellular CO 2 concentration (Ci) and transpiration (E) values of the kenaf [11,12]. The determination of the changes in these parameters during the day is limited to the study conducted in central Greece by [13].…”