Genotypic Variation in Cotton Genotypes for Phosphorus-Use Efficiency

Abstract

Low phosphorus (P) availability is a major constraint for cotton production. Consequently, P-efficient genotypes can improve productivity under conditions where the higher application of P is not economical. This study was conducted to characterize cotton genotypes for P-use efficiency under various P concentrations (0, 10, 20, 40, 80, and 500 μM KH2PO4). The results showed large genotypic variation in five selected traits, such as root dry weight, shoot dry weight, photosynthetic activity, P-utilization efficiency, and P-uptake efficiency. Based on these five selected traits, the genotypes were grouped into three main classes as efficient, moderate efficient, and inefficient genotypes as proposed by different researchers. Most of the genotypes behaved in a similar pattern under different P concentrations. Among the genotypes, Xinluzao-49 and Xinluzao-48 were considered as P efficient while CCRI-64 and Yumian-21 as inefficient genotypes. However, the rest of the genotypes were considered as moderately P efficient. The results prove that a large genetic potential exists in cotton genotypes for P-use efficiency, and the use of P-efficient genotypes for cultivation will reduce the application of phosphatic fertilizers. Furthermore, the use of P-efficient genotypes will improve cotton breeding activities and help in improving the environmental sustainability of cotton production.

Variations in Nitrogen Metabolism are Closely Linked with Nitrogen Uptake and Utilization Efficiency in Cotton Genotypes under Various Nitrogen Supplies

“…The increase in these morphological traits in N-efficient genotypes might be due to improve N uptake, photosynthetic activity, and N metabolism. The current results are consistent with the previous studies performed on Arabidopsis [11], maize [38], tomato [19], and cotton [39], where efficient genotypes performed better than inefficient genotypes. In addition, ANOVA showed that the genotypic effects accounted for 5%-30% of the total variance, suggesting that cotton genotypes have significant variations in morphological traits.…”

“…The previous study showed a positive correlation between leaf N concentration and photosynthesis [43,44] and, consistently, a positive correlation was noted between N concentration and photosynthetic activity (r = 0.93). Similarly, the increasing trend of photosynthesis with N supply in N-efficient genotype (CCRI-69) was consistent with our previous results [39], as well as results in poplar species [45,46]. Conversely, the photosynthetic activity in N-inefficient genotypes especially XLZ-30 decreased, which might have been due to inhibition in the photosystem, as many genes involved in the photosystem were downregulated under contrasting nitrogen supply [46].…”

“…Seven-day-old seedlings with uniform size were transplanted into plastic containers (7 L) in the growth chamber (16/8 h light/dark cycle, 28 • C temperature, 60% relative humidity). During the first week, the seedlings were provided with half-strength Hoagland solution, followed by full-strength according to Iqbal et al [39]. At two leaf-stage, seedlings were exposed to various N supplies 0.25, 0.5, 1, 2, 4, and 6 mM as Ca(NO 3 ) 2 .…”

High Nitrogen Enhance Drought Tolerance in Cotton through Antioxidant Enzymatic Activities, Nitrogen Metabolism and Osmotic Adjustment

“…The average of all the plants from treatments was worked out for mean shoot length. Similarly, lengths and widths of each leaf of six randomly selected plants were measured, then the mean single leaf area was calculated [66]. At the end of the experiment, seedlings were harvested and separated into shoot and roots, placed in labeled paper bags.…”

Nitrogen preference and genetic variation of cotton genotypes for nitrogen use efficiency

“…25 Similarly, the lengths and widths of each leaf were measured and the mean single leaf area was obtained from the product of length, width and correction factor (0.75). 26 The harvested plants were then put in the oven at 105°C for 1 h followed by 80°C for 48 h. The shoot and total plant dry weight of each plant was measured with the help of an electronic balance. At the end of the experiment, the root morphological parameters were measured by using a special image analysis software program WinRHIZO (Win/Mac RHIZO Pro V. 2002c Regent Instruments Inc., Québec, QC G1V 1V4, Canada) in combination with Epson Expression 11000XL scanner.…”