Review of the detasseling techniques for maize(Zea mays L.)hybrid seed production

Maize(Zea mays L.)is a critical staple crop globally,integral to human consumption,food security,and agricultural product stability.The quality and purity of maize seeds,essential for hybrid seed production,are contingent upon effective detasseling.This study investigates the evolution of detasseling technologies and their application in Chinese maize hybrid seed production,with a comparative analysis against the United States.A comprehensive examination of the development and utilization of detasseling technology in Chinese maize hybrid seed production was undertaken,with a specific focus on key milestones.Data from the United States were included for comparative purposes.The analysis encompassed various detasseling methods,including manual,semi-mechanized,and cytoplasmic male sterility,as well as more recent innovations such as detasseling machines,and the emerging field of intelligent detasseling driven by unmanned aerial vehicles(UAVs),computer vision,and mechanical arms.Mechanized detasseling methods were predominantly employed by America.Despite the challenges of inflexible and occasionally overlooked,applying detasseling machines is efficient and reliable.At present,China’s detasseling operations in hybrid maize seed production are mainly carried out by manual work,which is labor-intensive and inefficient.In order to address this issue,China is dedicated to developing intelligent detasseling technology.This study emphasizes the critical role of detasseling in hybrid maize seed production.The United States has embraced mechanized detasseling.The application and development of manual and mechanized detasseling were applied later than those in the United States,but latest intelligent detasseling technologies first appeared in China.Intelligent detasseling is expected to be the future direction,ensuring the quality and efficiency of hybrid maize seed production,with implications for global food security.

Management Options and Soil Types Differentially Affect Weeds in Maize Fields of Kakamega, Western Kenya

Maize production in Kenya is constrained by weed infestation and nutrient deficiencies. Field studies were conducted during the 2008/2009 cropping seasons to investigate weeds in maize fields on three dominant soil types in Western Kenya. Weeds were inventoried and their composition was compared using Jaccard＇s index. The economic importance of weed species （potential to reduce yields and the difficulty to control them by manual weeding） was assessed through participatory surveys. Finally, field trials assessed the effects of management options （farmer＇s practice, clean weeding, green manure, zero-tillage ＋ cover crop and zero-tillage） on weed biomass and species composition. Across the three soil types, 55 weed species in 21 families were identified. Soil types influenced species composition as confirmed by Jaccard＇s similarity indices of 0.50, 0.58 and 0.62 for Nitisol vs. Acrisol, Ferralsol vs. Acrisol and Nitisol vs. Ferralsol, respectively. The economically important weeds were Commelina benghalensis, Cynodon nlemfuensis, Bidens pilosa, Galinsoga parviflora and Leonotis nepetifolia. Management options significantly （P 〈 0.05） reduced weed biomass, irrespective of soil type and seasons. Maize biomass response was highest （7-16 Mg ha1） in zero-tillage and zero-tillage ＋ cover crop and lowest （2-8 Mg ha1） in farmer＇s practice. Significantly negative relationships （P 〈 0.01, r2 = 0.37 - 0.51） were established between leaf area index of maize and weed biomass across the soils. Zero-tillage combined with the use of a cover crop had the lowest weed biomass （〈 30% of the farmer practice） and thus appears to be a promising strategy combining soil fertility improvement with weed suppression in smallholder maize farming systems of Western Kenya.

Impact of sand burial on maize(Zea mays L.)productivity and soil quality in Horqin sandy cropland,Inner Mongolia,China

Croplands are often suffering from sand burial in dry regions of northern China. For studying this phenomenon, we carried out a case study of field experiment including four sand burial levels, i.e. shallow （1-3 cm）, moderate （8-12 cm） and deep （15-20 cm） sand burials, and no sand burial （control, CK）, in a typical agro-pastoral transitional zone in Naiman Banner of eastern Inner Mongolia. The aim of this study was to assess the impacts of sand burial on maize （Zea rnays L.） productivity and the soil quality along a gradient of burial depths. Results showed that there was a strong negative effect of sand burial on maize productivity and soil quality, which significantly declined （P〈0.05） under moderate and deep sand burial treatments. In comparison with the CK, the maize yield and above-ground biomass reduced by 47.41% and 39.47%, respectively. The soil silt and clay, soil water, soil organic carbon and total nitrogen contents under deep sand burial decreased by 67.85%, 40.32%, 86.52% and 82.11%, respectively, while microbial biomass carbon, microbial abundance and enzyme activity decreased by 89.78%, 42.28%-79.66% and 69.51%-97.71%, respectively. There was no significant effect on crop productivity and soil quality with shallow sand burial treatment. The correlations analysis showed that there was significant positive correlations of both maize yield and above-ground biomass with soil silt and clay, soil organic carbon and total nitrogen contents, pH, electrical conductivity, soil water content, microbial abundance and biomass and all tested soil enzyme activities. Stepwise regression analysis indicated that soil water and total nitrogen contents, urease, cellobiohydrolase and peroxidase activities were key determining factors for maize productivity. This combination of factors explains reason of the decreased maize productivity with deep sand burial. We found that degradation of cropland as a result of sand burial changed soil physical-chemical properties and soil enzyme activities in the plow layer, and decreased overall maize productivity. Furthermore, decreased soil enzyme activity was a better indicator to predict sandy cropland degradation.

Adoption of small-scale irrigation technologies and its impact on land productivity:Evidence from Rwanda

In an attempt to identify solutions to the effects of erratic rainfall patterns and droughts that limit agricultural production growth,the Rwandan government has recently increased investments in irrigation development.In this study,we analyze the adoption of small-scale irrigation technologies(SSITs)and its impact on land productivity using cross-sectional data from a sample of 360 farmers in Rwanda.The study uses the propensity score matching technique to address potential self-selection bias.Our results reveal that adoption decisions are significantly influenced by factors such as education,farm size,group membership,gender,extension services,access to credit,access to weather forecast information,risk perceptions,access to a reliable source of water for irrigation,awareness of rainwater harvesting techniques,and awareness of subsidy programs.In addition,the results show that the adoption of SSITs has a significantly positive impact on land productivity.The study concludes with policy implications that highlight the need to promote the adoption of SSITs among farmers as a strategy to improve agricultural productivity and food security in Rwanda.

Effects of irrigation water salinity on soil salt content distribution,soil physical properties and water use efficiency of maize for seed production in arid Northwest China

In order to explore the use of groundwater resources,field experiments were conducted for three consecutive years during 2012-2014 in the Shiyang River basin of Northwest China.Irrigation was conducted using four different water salinity levels that were arranged in a split plot design.These four water salinity levels were s0,s3,s6 and s9(0.71,3,6 and 9 g/L,respectively).The soil salt content,soil bulk density,soil porosity,saturated hydraulic conductivity,plant height,leaf area index and yield of maize for seed production were measured for studying the effects of saline water irrigation on soil salt content distribution,soil physical properties and water use efficiency.It was observed that higher salinity level of irrigation water and long duration of saline water irrigation resulted in more salt accumulation.Compared to initial values,the soil salt accumulation in 0-100 cm soil layer after three years of experiments for s0,s3,s6 and s9 was 0.189 mg/cm3,0.654 mg/cm3,0.717 mg/cm3 and 1.135 mg/cm3,respectively.Both greater salt levels in the irrigation water and frequent saline water irrigation led to greater soil bulk density,but poorer soil porosity and less saturated hydraulic conductivity.The saturated hydraulic conductivity decreased with increase in soil bulk density,but increased with improvement in soil porosity.It was noted that the maize height,leaf area index and maize yield gradually decreased with increase in water salinity.The maize yield decreased over 25%and the water use efficiency also gradually declined when irrigated with water containing 6 g/L and 9 g/L salinity levels.However,maize yield following saline water irrigation with 3 g/L decreased less than 20%and the decline in water use efficiency was not significant during the three-year experiment period.The results demonstrate that irrigation with saline water at the level of 6 g/L and 9 g/L in the study area is not suitable,while saline water irrigation with 3 g/L would be acceptable for a short duration together with salt leaching through spring irrigation before sowing.

Effects of irrigation and nitrogen management on hybrid maize seed production in north-west China

Scientific irrigation and nitrogen management is important for agricultural production in arid areas. To quantify the effect of water and nitrogen management on yield components, biomass partitioning and harvest index(HI) of maize for seed production with plastic filmmulching, field experiments including different irrigation and N treatments were conducted in arid north-west China in 2013 and 2014. The results indicated that kernel number per plant(KN) was signi ficantly affected by irrigation and N treatments. However, 100-kernel weight was relatively stable. Reducing irrigation quantity signi ficantly increased stem partitioning index(PI_(stem)) and leaf partitioning index(PIl_(eaf)), and decreased ear partitioning index(PI_(ear)) at harvest, but lowering Nrate(from 500 to 100 kg N$hm^(–2))did not signi ficantly reduce PI_(stem), PI leaf, andPIl_(eaf) at harvest. HI was signi ficantly reduced by reducing irrigation quantity, but not by reducing Nrate. Linear relationships were found between KN, PI_(stem), PI leaf,PIl_(eaf) at harvest and HI and evapotranspiration(ET).

Maize drought disaster risk assessment of China based on EPIC model

Digital Agriculture is one of the important applications of Digital Earth.As the global climate changes and food security becomes an increasingly important issue,agriculture drought comes to the focus of attention.China is a typical monsoon climate country as well as an agricultural country with the world’s largest population.The East Asian monsoon has had a tremendous impact upon agricultural production.Therefore,a maize drought disaster risk assessment,in line with the requirements of sustainable development of agriculture,is important for ensuring drought disaster reduction and food security.Meteorology,soil,land use,and agro-meteorological observation information of the research area were collected,and based on the concept framework of‘hazard-inducing factors assessment(hazard)-vulnerability assessment of hazard-affected body(vulner-ability curve)-risk assessment(risk),’importing crop model EPIC(Erosion-Productivity Impact Calculator),using crop model simulation and digital mapping techniques,quantitative assessment of spatio-temporal distribution of maize drought in China was done.The results showed that:in terms of 2,5,10,and 20 year return periods,the overall maize drought risk decreased gradually from northwest to southeast in the maize planting areas.With the 20 year return period,high risk value regions(drought loss rate]0.5)concentrate in the irrigated maize region of Northwest china,ecotone between agriculture and animal husbandry in Northern China,Hetao Irrigation Area,and north-central area of North China Plain,accounting for 6.41%of the total maize area.These results can provide a scientific basis for the government’s decision-making in risk management and drought disaster prevention in China.

GIS-based evaluation of maize cultivar lodging resistance performance in target growing environments

Lodging in maize is one of the major problems in maize production worldwide,which causes serious yield and economic losses annually.By evaluating cultivar lodging resistance performance in target growing environments before cultivar extension and application,the risks and losses can be significantly reduced.In this study,a GIS-based quantitative method for evaluating maize cultivar lodging resistance performance in target growing environments was established based on full cognition of environment stress,cultivar resistance,and the interaction between them.At first,comprehensive environment lodging stress is measured by three factors:1)extreme wind event in maize vegetative stage which is the direct factor,2)soil potassium content in target growing environment which is an indirect factor affecting corn stem sturdiness,and 3)planting density which is a human influence factor.Quantification methods of extreme probability analysis,spatial interpolation,normalization,and so on were used.Then,maize cultivar lodging resistance was determined using cumulative frequency distribution analysis of tested lodging data.At last,an evaluation matrix was established combining environment lodging stress and cultivar lodging resistance together,which was very simple and easy to understand method and the result is promising providing good direct support in practical cultivar application.The method used in this study,at county-level,cultivar-level and stress-level with GIS,can facilitate the identification of better-adapted growing environments for a specific maize cultivar,and provide direct support for maize cultivar recommendation and extension,so as to reduce the risk and loss of lodging in maize.It is more easy-operational and feasible than traditional surveying approach,especially for large-scale spatial trend analysis.So it is of both academic significance in accelerating precision agriculture development and practical significance in improving maize cultivar application.