Effects of varied water regimes on root length, dry matter partitioning and endogenous plant growth regulators in sunflower (Helianthus annuusL.)

Abstract

A field experiment was conducted to quantify the effect of varied water regimes on root length, partitioning of dry matter and plant growth regulators by using sunflower genotypes differing in maturity and drought tolerance. Significant depressing effect of drought stress was evident on traits (i.e., reproductive dry matter, leaf area index and cytokinin concentrations in leaves). However, root/shoot, reproductive/vegetative ratios and Abscisic acid (ABA) concentration were found to increase under drought stress. Drought stress also changed the dry matter accumulation pattern of genotypes. In most cases it reduced the days to reach the maximum peak showing early senescence. ABA was identified as a multi-functional plant growth regulator under drought stress, causing early senescence of plants and translocation of assimilates to the roots and reproductive part while root growth under drought stress was explained by the indole-acetic acid (IAA) concentrations. Maintaining higher cytokinin contents were involved in accumulation of higher reproductive dry matter under drought stress. Although ABA and IAA were both involved in the development of defense responses during the adaptation and survival to drought stress but higher productivity under drought stress was only realized through maintaining higher cytokinin contents.

Impact of Drought Stress during Germination on Antioxidant Capacities and Antioxidant Enzymes Activities of Madura Local Maize (<i>Zea mays</i>) Seeds

“…The result indicated that drought stress stimulates roots to lengthen and increased root number, to adapt against the stress. A similar result is reported by literature [23] root length were increased during the drought stress compared to a well-watered plant.…”

Physiological and biochemical performance of almond trees under deficit irrigation

“…5). In this regard, there have been reports on its accumulation in stressed plants (De Diego et al, 2013) and on the involvement of defense responses during plant adaptation to drought (Rauf and Sadaqat, 2007). This may be directly related to RWC, as in September 2015, there was significant difference between treatments, with a decrease compared to T100 of around 17% for non-irrigated treatment (Fig.…”

Competitiveness and Profitability of Intercropping Sunflower with Peanut under Different Irrigation Water Levels and Potassium Fertilizer Rates

“…These results may be due to the lowest irrigation water level diminished plant water contents of sunflower, then leaf water potential, biomass, cell enlargement and growth with closing stomata due to mainly turgor loss [32] [33]. Consequently, the lowest irrigation water level resulted in lessening leaf growth and decreasing relative dry matter portioning into the root and shoot/root ratio [34] which reflected negatively on head seed weight. Sunflower plants that suffered from water deficit in the root zone have small root system and weak shoot growth and this in turn reduce both the vegetative growth and the yield [35].…”