Nitrogen Fertilization Effects on Physiology of the Cotton Boll–Leaf System

Abstract

The objective of this study was to assess the impacts of nitrogen on the physiological characteristics of the source–sink system of upper fruiting branches under various amounts of nitrogen fertilization. A two-year field experiment was conducted with a Bt cotton cultivar in the Yellow River Basin of China. The growth and yield of cotton of the upper fruiting branches were compared under four nitrogen levels: Control (N0, 0 kg ha−1), low nitrogen (N1, 120 kg ha−1), moderate nitrogen (N2, 240 kg ha−1), and high nitrogen (N3, 480 kg ha−1). The results indicated that in the subtending leaves in upper fruiting branches, chlorophyll content, protein content, and peroxidase (POD) activity dramatically increased with nitrogen application, reaching the highest under the moderate nitrogen treatment. The physiological characters in the seeds had the same trends as in the subtending leaves. Furthermore, the moderate nitrogen rate (240 kg ha−1) had a favorable yield and quality. Our results supported that a moderate nitrogen rate (240 kg ha−1) could coordinate the source–sink growth of cotton in the late stage, enhance the yield and fiber quality, and decrease the cost of fertilizer in the Yellow River Basin of China and other similar ecological areas.

Fine root and root hair morphology of cotton under drought stress revealed with RhizoPot

“…Cotton is the world's second-most important oil crop and a crucial textile fibre crop (Xiao et al, 2019). The formation of crop yield is a complex process of the interaction between source and sink (Chen et al, 2019), and the morphological and physiological characteristics of the roots are closely related to the growth and development of the aboveground parts (Niu et al, 2018).…”

Physiological Characteristics of Cotton Subtending Leaf Are Associated With Yield in Contrasting Nitrogen-Efficient Cotton Genotypes

“…It also plays an important role in cotton growth and is required in large amounts as compared to other nutrients (Hou et al, 2007). The problem of N management in cotton is its indeterminate growth behavior (Chen et al, 2019), which results in imbalanced N fertilization that causes uneven growth (Niu et al, 2021). This inadequate N application leads to a 50% reduction in the yield (Jones et al, 2013;Iqbal et al, 2015).…”

“…As a result, a huge amount of N fertilizers are applied (Sarasketa et al, 2014) and their application may increase threefold in the coming decades (Good et al, 2004). The consequences of excessive N fertilization are prolonged vegetative growth (Chen et al, 2019), high cost of production (Hou et al, 2007), environmental pollution (Qiao et al, 2012), and lower N use efficiency (NUE) (Miao et al, 2011;Iqbal et al, 2020a). To decrease this costly and important production factor, there is an urgent need to develop/screen cultivars with high NUE (Den Herder et al, 2010;Kant et al, 2010).…”

Machine Learning Optimised Hyperspectral Remote Sensing Retrieves Cotton Nitrogen Status

“…Being able to remotely and rapidly identify the nitrogen level in plants and tailor farm management to either boost higher yield potential zones or reduce inputs to lower potential areas promises a way to reduce environmental impact while increasing profits. Nitrogen is a key nutrient in cotton (Gossypium hirsutum L.), essential for photosynthesis and thus undersupply will hamper lint and seed production, while oversupply can damage local ecosystems and adversely affect yield [1][2][3][4]. It's been widely reported for decades that nitrate leaching into the groundwater [5] and emission as oxides into the atmosphere [6] cause extensive local and global environmental damage, with, for example, intensive agriculture in the USA contributing to~400 hypoxic zones in coastal marine ecosystems from farms upstream [7].…”

“…For example, normalised difference red edge was developed to use the red edge region rather than red to minimise the impact of canopy density and improve characterisation of chlorophyll content [10,37]. There is a high correlation between chlorophyll content and N concentration in cotton canopy leaves, most likely because the main pigments used in photosynthesis in the chloroplasts, chlorophyll a and b, contain N [4,28,41].…”