Phosphorus acquisition characteristics of cotton (Gossypium hirsutum L.), wheat (Triticum aestivum L.) and white lupin (Lupinus albus L.) under P deficient conditions

Abstract

A rhizobox experiment was conducted to examine the P acquisition characteristics of cotton (Gossypium hirsutum L.), wheat (Triticum aestivum L.) and white lupin (Lupinus albus L.) under P-deficient conditions. We aimed to identify whether cotton is physiologically efficient at acquiring P through release of protons, phosphatases or carboxylates. Plants were pre-grown in the upper compartment of rhizoboxes filled with a sand and soil mixture to create a dense root mat against a 53 μm polyester mesh. For each species, two P treatments (0 and 20 mg P kg −1 ) were applied to the upper compartment in order to create P-deficient and P-sufficient plants. At harvest, the upper compartment with intact plants was used for collection of root exudates while the lower soil compartment was sliced into thin layers (1 mm) parallel to the rhizoplane.Noticeable carboxylates release was only detected for white lupin. All P-deficient plants showed a capacity to acidify their rhizosphere soil to a distance of 3 mm. The activity of acid phosphatase was significantly enhanced in the soil-root interfaces of P-stressed cotton and wheat. Under P-deficient conditions, the P depletion zone of cotton from the lower soil compartment was narrowest (<2 mm) among the species. Phosphorus fractionation of the rhizosphere soil showed that P utilized by cotton mainly come from NaHCO 3 -P i and NaOH-P o pools while wheat and white lupin markedly depleted NaHCO 3 -P i and HCl-P pools, and the depletion zone extended to 3 mm. Wheat also depleted NaOH-P o to a significant level irrespective of P supply. The study suggests that acquisition of soil P is enhanced through P mobilization by root exudates for white lupin, and possibly proton release and extensive roots for wheat under P deficiency. In contrast, the P acquisition of cotton was associated with increased activity of phosphatases in rhizosphere soil.

Phosphorus use efficiency in pima cotton (Gossypium barbadense L.) genotypes

“…In the PS treatment, BUE ranged from 16.27 (MT 124) to 5.99 (MT 110) g g -1 , while in the PD treatment, it ranged from 9.67 to 1.59 g g -1 . In another study, significant BUE differences were observed in six cotton genotypes cropped under both low and sufficient P conditions (Wang et al, 2008). In the present study, it was higher in MT 102, MT 105, and MT 112 for the PS and PD treatments (Table 4).…”

“…With regards to ARE, it was higher in MT 101, MT 92, and MT 124 than in other genotypes, and it exhibited, on the average, 6% of accumulated P in the plant per applied P unit. This result shows the best P recovery from fertilizer by these genotypes (Wang et al, 2008). Cotton response to soil P application in soil in the Cerrado is higher than that of rice cropped under similar conditions in the highlands.…”

“…A decrease in ToDM as a result of P application is also a useful parameter to evaluate the relative tolerance of cotton varieties to soil P deficiency (Dorahy et al, 2004). Cotton genotypes that do not change DM production in response to P supply (sufficient or deficient) are best grown in soils with low P content (Wang et al, 2008).…”

“…When P limits plant growth, roots become a strong carbohydrate sink, limiting shoot rather than root growth (Wang et al, 2010). Bean roots grown under P-deficiency conditions show higher sugar levels than those grown under sufficient P supply because of higher photoassimilate transport from shoot to root (Wang et al, 2008). With regards to ARE, it was higher in MT 101, MT 92, and MT 124 than in other genotypes, and it exhibited, on the average, 6% of accumulated P in the plant per applied P unit.…”

<b>Phosphorus uptake and use efficiency of different cotton cultivars in savannah soil (Acrisol)

“…P efficiency studies require two levels of P availability to identify efficient and inefficient cultivars (Fageria & Baligar, 1997;Ahmad, Hans-peter, Johann, Josef, & Walter, 2014). Although previous research has found a strong correlation between cotton P uptake and the proportion of P bonded to iron and aluminum oxides (Dohary, Rochester, & Blair, 2004;Wang, Tang, Guppy, & Sale, 2008) as well as a weak correlation between cotton P uptake and P fertilization in alkaline soils (Bronson et al, 2001), further work is needed to better understand and evaluate the P use efficiency of cotton plants.…”