Physiological and biochemical appraisal for mulching and partial rhizosphere drying of cotton

Abstract

Water is the main factor for the healthy life of plant. One of the main negative effects of climate change is the increasing scarcity of water that is lethal for plant. Globally, for water deficit regions (arid and semi-arid), drought is the main factor responsible for low production of agriculture, especially for cotton. Great efforts have been and are being made to find alternatives to water saving practices. This study aimed to examine the effects of partial rhizosphere drying (PRD, half of the root system irrigated at one event, and the other half irrigated in the next event, and so on) with and/or without various mulching treatments on physiological and biochemical traits of cotton. To explore this objective, we laid out experiments in completely randomized design with factorial arrangement in the Islamia University of Bahawalpur, Pakistan in 2016. Two factors included were four mulching treatments (M 0 , no mulching; M 1 , black plastic mulching; M 2 , wheat straw mulching; and M 3 , cotton sticks mulching) and two irrigation levels (I 0 , control (full irrigation); and I 1 , PRD). Fisher's analysis of variance among means of treatments was compared using least significant difference test at 5% probability level. Results revealed that the maximum plant height, leaf area, leaf gas exchange (photosynthetic rate and stomata conductance), chlorophyll, proline and total sugar contents, and enzyme activities were higher under M 2 than under other three mulching treatments. As for irrigation levels, higher values of plant height, photosynthesis and water related parameters (leaf water potential, leaf osmotic potential, leaf turgor potential, etc.) were recorded. Contents of total sugar and proline and activities of antioxidant enzymes were significantly higher in PRD-treated plants than in control plants. It was concluded that combined application of PRD and mulching was more effective than the rest of the treatments used in the experiment. Similar study can be conducted in the field by applying irrigation water in alternate rows in semi-arid regions.

Partial root-zone drying (PRD), its effects and agricultural significance: a review

“…There is an increased production of ABA during the drying phase of roots as in PRD as compared to normal conditions of soil (Iqbal et al 2019a;Davies and Zhang 1991), and this ABA concentration is moved in upper parts of plants as an anti-stress chemical signal of roots to limit the stomatal conductance and conserve water in plants which would otherwise transpire through stomatal openings (Iqbal et al 2019b;Stoll et al 2000;Bauerle et al 2006;Kang and Zhang 2004;Liu et al 2006a;Liu et al 2005b). There was significant leaf expansion rate in maize due to the usage of PRD (Bahrun et al 2002), wheat crop (Ali et al 1999), soybean crop (Liu et al 2005a), potato crop (Liu et al 2005c), and tomato crop (Topcu et al 2007).…”

“…Its main benefit is the irrigated side provides water to the plant and, in this way, the water potential remains at such a level that there is no stress to the crop plants. Secondly, the dry portion causes the production of ABA, which in turn, decreases the conductance of stomata (Iqbal et al 2019a(Iqbal et al , 2019bSaeed et al 2008;Tang et al 2005;Du et al 2008b;Costa et al 2007;Shahnazari et al 2007) and increases water use efficiency (Davies et al 2002). Many of the practical studies conducted in different regions show no doubt that stomatal conductance reduces using PRD but the rate of photosynthesis remains the same, as in the case of fully irrigated crop (Raza et al 2017;Ahmadi 2009;Costa et al 2007;Ahmadi et al 2010).…”

“…Different scientists have conducted many different experiments using diverse crops in PRD such as Du et al 2008a, Tang et al 2005, Du et al 2006, and Iqbal et al 2019b (cotton crop experiments); Kang et al 2001 (hot pepper); Kang et al 2000a, Kang et al 2000b, and Du et al 2010 (maize crop experiments); Du et al 2008b andDe la Hera et al 2007 (grapes experiments); Liu et al 2006a, and Ahmadi et al 2010; Campos et al 2009 andZegbe et al 2004 (tomato); and Zegbe and Behboudian 2008 conducted experiments on apples and concluded that the photosynthetic rate is not lessened as compared to the crop which is fully irrigated. On the other hand, studies of Liu et al 2006b (potato) and Kirda et al 2005 (maize) suggested that by using PRD, there was a significant reduction in the photosynthesis rate.…”

“…In some research studies, there was even better fruit quality due to partial root drying (PRD) (Du et al 2008b;Guang-Cheng et al 2008;Kirda et al 2004;Leib et al 2006;Kang and Zhang 2004;Shahnazari et al 2007;Du et al 2008a). PRD work is still ongoing from the last decade in reference to different horticultural and agronomical crops (Iqbal et al 2019a(Iqbal et al , 2019bAhmad et al 2020;Rashid et al 2019), along with the development of some other irrigation techniques and methods (Ahmadi 2009;Morison et al 2008;Guang-Cheng et al 2008).…”

“…They concluded that using PRD technique reduced watering system by 30%; at the same time, its economic yield was lessened by 8% which was not statistically significant in relation to FI. Iqbal et al (2019b) concluded that a superior development and a higher photosynthesis rate in cotton were seen under full water system (FI) than under PRD water system; be that as it may, the proline and all other sugar substance, and concentrations of antioxidants were fundamentally higher in cotton plants under PRD water system than under full water system. Then again, mulching affected soil moisture (Kader et al 2019;Iqbal et al 2020) and henceforth essentially improved the proficiency of PRD water system.…”