Cultivation system influenced the critical period for weed control in cotton field

Background The critical period of weed control(CPWC) refers to the period of time during the crop growth cycle when weeds must be controlled to prevent yield losses.Ultra-narrow row(UNR) is a method of planting of cotton in rows that are 25 cm or less apart.Amongst cultural techniques for weed control,the use of narrow row spacing is considered to be a most promising approach that can effectively suppress weed growth and provide greater yields in cotton.This cultivation system can shorten the length of the critical weed-crop interference duration and results in greater yield.The current research aimed to determination of critical time of weed control in cotton(Gossypium hirsutum L.) under conventional and ultra-narrow row spacing conditions.Field experiments were arranged as factorial experiment in a randomized complete block design with three replications.Factors were cultivation system(conventional(50 cm row spacing) and ultra narrow row(25 cm row spacing and weed treatment including 30,45,60,and 75 days weeding after emergence during the growing season(weed free),and 30,45,60,and 75 without weeding(weed infested) in the growing season along with weedy and weed-free from sowing to harvesting.A four-parameter loglogistic model was fit to the two sets of relating relative crop yield to data obtained from increasing durations of weed interference and lengths of weed-free period.Results In both years and cultivation systems,the relative yield of cotton decreased with the increasing duration of weed-interference but increased with the increasing duration of weed-free period.Ultra-narrow row cultivation delayed the beginning of the CPWC in cotton.Under ultra-narrow row condition,the CPWC ranged from 21 to 99 days after germination in 2021 and 23 to 91 days in 2022 based on the 5% acceptable yield loss.Under conventional cultivation CPWC ranged from 17 to 102 days after emergence in 2021 and 18 to 95 days after emergence in 2022.Conclusions Under both conventional and Ultra-narrow row conditions,weed interference reduces seed yield.Under ultra-narrow row condition,weed interference until 21.1–23.5 days after cotton emergence and under conventional condition,weed interference until 16.9–18.5 days after cotton emergence had not significant reduction on cotton yield.

The effect of time and type of stress moderators on yield and yield components of cotton on conventional and double‑cropping systems under saline conditions

Background:Today,stress moderators are employed to mitigate crop loss due to the adverse effects of environmental stress.The current research aimed to investigate the impacts of time and stress moderator types on agro-physiological responses of cotton on conventional and double-cropping systems during 2017 and 2018 under saline conditions.A split-plot factorial experiment was carried out in a randomized complete block design with three replications.Cultivation system[conventional(recommended planting date)and double-cropping systems(sowing after harvest of wheat)]were considered as the main plots,and stress moderator type at four levels[water control,2 mmol·L^(-1) Salicylic acid(SA),100 mmol·L^(-1) Glycine betaine(GB),and 100μmol·L^(-1) sodium nitroprusside(SNP)]and application time(flowering and flowering+bolling stages)were regarded as subplots.Results:Plant height,reproductive branch number,the number of bolls,10-boll weight,1000-seed weight,biological yield,seed cotton yield,lint yield,chlorophyll a,chlorophyll b,carotenoids,total chlorophyll,sodium,potassium,and proline content were less in double-cropping system comparing with conventional system.Spraying with the stress moderators alleviated soil salinity effects on yield,yield components,and biochemical traits of cotton.SNP spraying led to maximum plant height,branch number,the number of bolls per plant,10-boll weight and seed cotton yield.SA spraying yielded the highest 1000-seed weight,biological yield,lint percentage and lint yield.The highest chlorophyll a,chlorophyll b,carotenoids,and total chlorophyll content resulted from SNP spraying.Yield,yield components,and biochemical traits did not respond to the stress moderator types in double-cropping system.However,the highest chlorophyll a,carotenoids,proline content,the number of bolls per plant,and seed cotton yield resulted from SNP spraying in conventional system.No statistically significant differences were observed between spraying with SNP and SA in most studied traits.Conclusions:The results suggest that the optimum cotton planting time and SNP spraying could be recommended for producing the most suitable yield under saline conditions.Highlights:External application of stress modulators increases salinity stress tolerance.Spraying with sodium nitroprusside has more moderating effect.Agro-physiological response of cotton to moderators is stronger in early sowing.Maximum seed cotton yield was achieved at early sowing and spraying sodium nitroprusside.Delayed cultivation reduces cotton yield.