Reduced dose coupled with improved method of neem-coated urea application and foliar sprays of KNO₃ enhance cotton yield and fiber parameters under semi-arid climates

Choice of source, nitrogen rate, and its application method affect cotton productivity. In absence of new recommendations for recently introduced neem-coated urea (NCU) in India, farmers have been applying either similar or above optimal levels of NCU in cotton just like conventional urea. The present study aimed to evaluate the optimum dose and better method of NCU application to improve cotton productivity and profitability under arid climates. A total of eight different treatments were evaluated in a randomized complete block design. Two NCU doses [i.e., 112.5 kg ha−1 (75% of conventional nitrogen [urea] recommendation-CNR) and 150 kg ha−1 (100% of CNR)] were applied using three methods, i.e., (a) band application, (b) spot application, and (c) broadcasting constituted six treatments. In addition, foliar sprays of NCU@1% and KNO3@2% were also evaluated to study their effect in improving seed cotton yield (SCY) and fiber parameters. These findings elucidated that the spot method of NCU application proved better than the broadcasting and band application method owing to better nitrogen use efficiency (NUE). NCU@ 112.5 kg N ha−1 applied through spot application along with three foliar sprays of KNO3@2% resulted in similar profitability as that of broadcasting 150 kg NCU ha−1 along with four foliar sprays of KNO3. Improved physiological parameters like net photosynthesis and chlorophyll coupled with higher NUE played a decisive role for at par SCY despite 25% low nutrient input besides enhanced environment safety. Therefore, under semi-arid climates, 37.5 kg N ha−1 could be saved without compromising cotton productivity.</p

Synthetic diet composition for delivery of dsRNA in cotton leafhopper through membrane feeding.

<p>Synthetic diet composition for delivery of dsRNA in cotton leafhopper through membrane feeding.</p

Selection of housekeeping genes and demonstration of RNAi in cotton leafhopper, <i>Amrasca biguttula biguttula</i> (Ishida) - Fig 6

<p>Expression of candidate genes in A. <i>biguttula biguttula</i> fed with dsRNA containing liquid diet by membrane feeding assay (A) Abb IAP (Inhibitor of Apoptosis) knockdown, (B) Abb AQP (Aquaporin) knockdown, (C) VATPase knockdown, (D) Snf7 (Multivesicular protein) knockdown. The mRNA levels of each gene have been normalized with ribosomal protein (RP13) as a reference gene. The error bars represent the standard deviation (n = 3) and * represents significant differences in mRNA levels compared to that in control—fed on dsGFP (P ≤ 0.05, Student’s t-test).</p

Annotation of different target genes of cotton leafhopper from RNA sequence data using BlastoGo software and primers used for expression analysis of housekeeping genes.

<p>Annotation of different target genes of cotton leafhopper from RNA sequence data using BlastoGo software and primers used for expression analysis of housekeeping genes.</p

Corrected percent mortality in the leafhopper nymphs at 48h after dsRNA feeding.

<p>Corrected percent mortality in the leafhopper nymphs at 48h after dsRNA feeding.</p

The overall ranking of housekeeping genes in cotton leafhopper across different stages as well as starvation stress by Delta CT, BestKeeper, Normfinder and genorm algorithms.

<p>The overall ranking of housekeeping genes in cotton leafhopper across different stages as well as starvation stress by Delta CT, BestKeeper, Normfinder and genorm algorithms.</p

Stability values of all candidate reference genes estimated by Normfinder across all developmental stages and starvation stress.

<p>Stability values of all candidate reference genes estimated by Normfinder across all developmental stages and starvation stress.</p

Visualization of different dsRNA on 1% agarose gel.

<p>The dsRNA was synthesized for RNAi studies in cotton leafhopper using diet bioassay.</p

Description of all candidate gene primers used for RNAi and target gene expression in cotton leafhopper.

<p>Description of all candidate gene primers used for RNAi and target gene expression in cotton leafhopper.</p

NormFinder analysis revealed stability values across the developmental stages and starvation stress.

<p>NormFinder analysis revealed stability values across the developmental stages and starvation stress.</p