VIETNAM NATIONAL UNIVERSITY OF AGRICULTUREFACULTY OF AGRONOMY ------UNDERGRADUATE THESIS TITLE: EFFECT OF BIOCHAR ON GROWTH AND PHYSIOLOGY OF SUGARCANE UNDER SALINITY CONDITION HANOI -
INTRODUCTION
Introduction
Salinity is a major abiotic stress that significantly impacts crop productivity, exacerbated by climate change and inadequate land management practices Over 100 countries experience salt-affected soils, particularly in arid and semi-arid regions This salt stress results in reduced dry matter yield, water and osmotic stress, and diminished chlorophyll content, ultimately affecting gas exchange variables Additionally, research indicates that photosynthetic activity declines in plants exposed to salinity, further hindering growth and productivity.
Sugarcane (Saccharum officinarum L.) is a major sugar producing plant.
Sugarcane is a high biomass producer that requires significant water and nutrient intake from the soil to reach its full productivity As a glycophyte, it struggles with salinity, often experiencing stunted growth and a yield reduction of 50% or more compared to its potential.
Numerous studies have investigated the physiological effects of salinity on sugarcane, highlighting its impact on growth and ion concentrations Research by Errabii et al (2007) examined the effects of salt and mannitol stress on sugarcane calli, while Patade et al (2008) reported a reduction in growth when calli were exposed to lethal salt concentrations, suggesting that this reduction may result from the combined or individual effects of osmotic and toxic components of salinity.
Biochar is produced through the pyrolysis process, where organic material is charred in a low-oxygen environment (Abel et al., 2013) Its recent popularity as a soil amendment has garnered significant interest (Saifullah et al., 2018).
Biochar enhances soil quality and crop productivity by improving the availability of essential nutrients like potassium (K\(^+\)) and reducing sodium (Na\(^+\)) absorption It also enriches soil physicochemical and biological properties, as well as enzymatic activity, which collectively boost plant water status.
Xu et al (2015) found that incorporation of biochar to soils planted with groundnuts significantly increased yields Chintala et al., 2014 and Akhtar et al.,
2014 reported that biochar greatly increased the water holding capacity of soil, physiology characteristics such as chlorophyll content, stomatal conductance, photosynthetic rate, and relative water content under water deficient conditions.
Recent studies have explored the use of biochar as a soil conditioner in salt-affected soils, highlighting its potential to enhance fruit quality by mitigating soil soluble salt levels during saline water irrigation For instance, Usman et al (2016) examined the impact of biochar on soil nutrient availability and tomato growth under saline conditions Similarly, Lashari et al (2013) found that biochar amendment improved growth, physiology, yield, and nutrient uptake of wheat under salt stress Consequently, this study aims to investigate the effects of biochar on the growth and physiology of sugarcane, emphasizing its potential to enhance sugarcane performance in saline environments.
Objectives and requirements
This research investigates the impact of biochar on the growth and physiological responses of sugarcane seedlings subjected to saline conditions The findings aim to demonstrate biochar's potential to enhance sugarcane growth and physiological performance in saline environments.
Evaluating the effect of biochar on growth parameters of sugarcane under salinity condition.
Evaluating the effect of biochar on physiology parameters of sugarcane under salinity condition.
LITERATURE REVIEW
Situation of sugarcane production on the world and in Vietnam
2.1.1 Situation of sugarcane production in the world
Sugarcane is the most widely cultivated crop globally, grown in over 90 countries, primarily in tropical and subtropical regions Recognized as one of the oldest industrial crops, it plays a crucial role in supplying sugar and energy worldwide India leads in sugarcane processing technology, with its influence extending to China and spreading across Arab, African, European, American, and Australian regions.
Sugarcane belonging to the genus Saccharum, comprises of six species.
There are two confirmed wild species of sugarcane: S spontaneum and S robustum Additionally, four domesticated species exist: S officinarum, S sinense, S barberi, and S edule Currently, all commercial sugarcane varieties are hybrids created from the breeding of S officinarum and S spontaneum, with contributions from S sinense, S robustum, and S barberi (Bakker, 1999).
Sugarcane is a vital industrial crop in the sugar industry, serving as the primary source of sugar, which is essential for the food processing sector and provides energy for the body Despite its long history of over 200 years, the sugar industry has recently undergone significant mechanization and rapid growth According to the Food and Agriculture Organization (FAO), sugarcane ranks among the world's largest crops by production, far surpassing sugar beet as a sugar source Today, sugarcane is predominantly cultivated in tropical and subtropical regions.
As of 2018, sugarcane was cultivated in 104 countries, with Brazil leading in both area and production Brazil has an extensive sugarcane cultivation area of 10 million hectares, followed by India at approximately 4.7 million hectares and China at around 1.4 million hectares In terms of production, Brazil also tops the list, yielding 746.8 million tons of sugarcane, according to FAOSTAT.
Table 2.1: World sugarcane production in recent years
Table 2.1 illustrates significant changes in the global harvested area, production, and yield of sugarcane Between 2010 and 2018, the harvested area expanded from 23.69 million hectares to 26.27 million hectares Sugarcane yield saw fluctuations, initially rising from 78.31 tons per hectare in 2010 to 78.06 tons per hectare in 2013, before declining to 77.69 tons per hectare in 2016 However, by 2018, the yield increased dramatically to 80.02 tons per hectare Notably, sugarcane production peaked at 1,907.02 million tons in 2018.
Table 2.2 Sugarcane production in major continents in recent years
Table 2.2 reveals a significant increase in sugarcane production from 2017 to 2018, with Asia producing approximately 56,000 million tons, the Americas 338 million tons, and Africa 500 million tons In contrast, Europe and Oceania experienced declines of nearly 400 million tons and over 3,000 tons, respectively Notably, the Americas had the largest harvested area for sugarcane, totaling 13,920 million hectares in 2018, despite a decline in harvested area.
44 million ha compared with 2017, the sugarcane yield and production still increased from 80.711 to 80.994 tons/ha of the yield and from 1022.448 to1022.786 million tons of the production.
Sugarcane production in Vietnam
In Vietnam, sugarcane have been grown for a long time in all provinces.Sugarcane is one of the traditional crops with many purposes: refreshments,molasses, sugar, fertilizer and medicine.
Table 2.3 Area, yield and production of sugarcane in Vietnam compared with the world (2018)
According to FAO’s forecast, the area, yield, and production of sugarcane were about 0.269 million hectares; 73.41 tons/ha, 17.9 million tons, respectively (Table 2.3)
Table 2.4 Sugarcane production by regions in Vietnam, 2017-2018
North & North Central 66,917 59.7 3,993,225 Central Coast – Central Highlands 123,242 60.3 7,433,706
In Vietnam, sugarcane had many advantages over other short-term crops.
Sugarcane is a highly adaptable and easy-to-cultivate crop, known for its resilience to harsh environmental conditions and its regenerative capabilities, which help lower production costs This multipurpose plant offers significant economic benefits, as its stems can be utilized for various products, including sugar, wine, paper, plywood, pharmaceuticals, and electricity In terms of natural resources, Vietnam possesses medium potential for sugarcane cultivation, with the crop being grown across multiple regions, including the North, North Central, Central Coast, Central Highlands, Southeast, and the Mekong River Delta.
Saline soil and the influence of salinity on the growth and development
Saline soils are formed through a combination of factors including source rock, low-lying terrain, shallow saltwater levels, dry climates, and salt-tolerant organisms Groundwater salinity is the primary contributor to these soils, which contain 1-1.5% or more dissolved salts such as NaCl, Na2SO4, CaCl2, CaSO4, MgCl2, and NaHCO3 These salts originate from various sources, including volcanic rock minerals, and accumulate in poorly drained areas In tropical regions like Vietnam, intense weathering processes can dissolve even insoluble salts, leading to their transport into rivers and seas.
Salinity is categorized into two types: seawater-induced salinity and continental salinity Seawater salinization occurs when seawater intrudes into inland areas during high tides, storms, or when river flows are weak, allowing saltwater to penetrate through soil cracks and sea dykes In contrast, continental salinity arises in arid or semi-arid regions where salts accumulate in the soil due to insufficient water drainage This process is primarily driven by capillary rise from groundwater, along with salt transfer by wind and precipitation from higher terrains Additionally, irrational irrigation practices can exacerbate salinization by locking in salts within the soil.
According to the FAO-UNESCO classification, saline soils in Vietnam are categorized based on the electrical conductivity of the soil solution and the percentage of dissolved salts.
- Salty land of Mangroves (Mn) - Gleyi Salic Fluvisols (FLsg)
- Highly salty soil - Hapli salic Fluviols (FLsh) has total dissolved salts > 1%, in which Cl - > 0.25% and EC conductivity is usually greater than
- Medium and low saline soils - Molli Salic Fluvisols (FLsm) have Cl -