Correlation and Principal Component Analysis on Main Agronomic Traits of New Waxy Corn Varieties

[Objective] This study was conducted to provide certain theoretical reference for the comprehensive evaluation and breeding of new fresh waxy corn vari- eties. [Method] With 5 good fresh waxy corn varieties as experimental materials, correlation analysis and principal component anatysis were performed on 13 agronomic traits, i.e., plant height, ear position, ear weight, ear diameter, axis diameter, ear length, bald tip length, ear row number, number of grains per row, 100-kernel weight, fresh ear yield, tassel length, and tassel branch number. [Result] The principal component analysis performed to the 13 agronomic traits showed that the first three principal components, i.e., the fresh ear yield factors, the tassel factors and the bald top factors, had an accumulative contribution rate over 87.2767%, and could basically represent the genetic information represented by the 13 traits. The first principal component is the main index for the selection and evaluation of good corn varieties which should have large ear, large ear diameter but small axis diameter, i.e., longer grains, larger number of grains per ear, higher, 100-grain weight and higher plant height. As to the second principal component, the plants of fresh corn varieties are best to have longer tassel and not too many branches, and under the premise of ensuring enough pollen for the female spike, the varieties with fewer tassel branches shoud be selected as far as possible. From the point of the third principal component, bald tip length affects the marketing quality of fresh corn, and during fariety evaluation and breeding, the bald top length should be control at the Iowest standard. [Conclusion] The fresh ear yield of corn is in close positive correlation with ear weight, 100-grain weight, ear diameter, number of grains per row and ear length, and plant height also affects fresh ear yield.

Reasearch on Occurrence Rules of Asian Corn Borer Ostrinia furnacalis in the Field of Waxy Corn

[Objective] This program aimed at providing basis for timely and effective control of Asian corn borer Ostrinia furnacalis in waxy corn fields through investigations and researching on occurrence and damage characteristics of Ostrinia furnacalis in the main producing area of waxy corn of Shanxi Province.[Method] Attraction and collection of the adults,fixed-points and random investigations on eggs and larvae were the main methods in this research.[Result] Ostrinia furnacalis appeared in two generations per year in the field of waxy corns,the generations were basically nonoverlapping with significant interval.The peak period of the overwintering generation adults in the field of waxy corn was early to middle of June,peak period of the first generation adults was from early August to late August;peak period of the first generation eggs was from the end of early June to the binning of late June,the peak period of the second generation eggs was from the middle of early August to late August.Egg-laying performances of Ostrinia furnacalis on waxy corns in different growth period suggested that the temptation of waxy corns to egg-laying of Ostrinia furnacalis had gradually increased with the continuation of growth stages before the heading of waxy corns;while after the heading of waxy corns,the temptation of waxy corns to egg-laying of Ostrinia furnacalis had gradually reduced with the continuation of growth stages.The amount of eggs on waxy corns was more than eggs on normal corns with the same growth period and growth conditions.The first generation of Ostrinia furnacalis caused more serious damages than the second generation.The first generation larvae caused more serious damages on waxy corns with early sowing period than with middle sowing period,while the late sowing fields basically uninjured.The early sowing and middle sowing corns were damaged but lightly,due to the slight occurrence of the first generation larvae.The second generation larvae caused more serious damages in late sowing waxy corn field than in middle sowing waxy corn field.As the early sowing waxy corns were harvested before the beginning of damage peak period of the second generation larvae,they were basically uninjured or slightly damaged by the second generation larvae in general years.Because the second generation larvae were in large-scale occurrence,they had caused serious damages to late and later middle sowing waxy corns.Incidence of ear rot disease on the female ears of waxy corns was closely related to the damages of Ostrinia furnacalis on ears,which was higher on the ears infested by Ostrinia furnacalis.[Conclusion] Comprehensive control on the second generation of Ostrinia furnacalis in the mid and late sowing field of waxy corn should be strengthened.

Analysis on Waxy Corn/Soybean Intercropping Pattern and Economic Benefit

The research mainly analyzed effects of waxy corn/soybean intercropping on yields of the two crops, as well as agronomic characters, and the economic benefits of the mode. The results showed that although yields of waxy corn and soybean went down by 21.19% and 31.04% per unit area, land equivalent ratio（1.48） kept higher than 1, suggesting the intercropping improves land use rate. Besides, due to the practice of intercropping, many characters of waxy corn grew, but of soybean declined. The economic benefits from high to low were waxy corn/soybean intercropping, monoculture of waxy corn, and monoculture of soybean.

Analysis on Genetic Characteristics of Leaf Angle in Waxy Corn

The leaf angle in waxy corn is a significant trait for breeding corn with compact plant type, which is beneficial to improve yield. According to the Griffing method II, the GCA （general combining ability） and SCA （specific combining ability） of leaf angle trait in the 7 waxy corn inbred lines and 21 combinations were esti-mated, and the genetic characteristics of leaf angle in corn were also analyzed. The results showed that among the 7 inbred lines, the GCA values ranked as N22 〉N8 〉 N28 〉 N7 〉 N23 〉 N27 〉 N4. The GCA of N27 showed great negative ef-fect, and the genetic variance of its SCA was lower. It suggested that the N27 can be used as an ideal parent for breeding excel ent combinations with smal leaf angle and compact plant type. The inheritance of leaf angle trait in waxy corn is in ac-cordance with the model of ＂additive - dominant - epistatic＂. The efficiency of leaf angle trait is control ed by recessive genes. The broad heritability of leaf angle trait in waxy corn is relative low （68.5%）, but its narrow heritability is relatively high （72.62%）. In the breeding practices, the early-generation selection is more suitable for the leaf angel trait.

Development Situation and Strategy Analysis of Waxy Corn Processing Industry in Chongqing Municipality

With the development of society and economy and increasing awareness of people's diet and health care,the demand for waxy corn and its processed products has been rising. At present,the planting of waxy corn in Chongqing is taking shape,but the waxy corn processing is still in the initial stage with smaller enterprise scale and fewer processing product variety. Based on the analysis of the development advantages and disadvantages of waxy corn processing industry in Chongqing,this paper brings forward the development ideas and strategies of Chongqing waxy corn processing industry from three aspects of production,processing and policy.

Structure,retrogradation and digestibility of waxy corn starch modified by a GtfC enzyme from Geobacillus sp.12AMOR1

To lower the retrogradation and digestibility of waxy corn starch for different food applications,a novel thermostable GtfC type 4,6-α-glucanotransferase without N-and C-terminals(GsGtfC)from Geobacillus sp.12AMOR1 was used.Waxy corn starch of 50 g/L was incubated with GsGtfC of 40-100 U/g substrate at 65℃and pH 5.5 for 1 h.Its molecular weight,iodine affinity,XRD crystallinity,and FTIR ratio of heights of bands at 1047 and 1022 cm^(-1) decreased,but ratio of DP<6 to DP≥25 branches and degree of branching increased.GsGtfC cleavedα-1,4-glycosidic bonds and inducedα-1,6-branching points to produce reuteran-likes polymers,which is different from Exiguobacterium sibiricum GtfC enzyme cleavingα-1,4-glycosidic bonds and synthesizing consecutiveα-1,6-glycosidic bonds to produce isomalto/malto-oligosaccharides.GsGtfC modified waxy corn starch had significantly lower DSC retrogradation enthalpies during the storage at 4℃for 3-14 days and significantly lower released glucose during the incubation with mammalian mucosalα-glucosidase at 37℃for 10-360 min.GsGtfC at 100 U/g substrate increased slowly digestible portion from 11.07%to 24.11%.

Invasion of fall armyworm led to the succession of maize pests in Southwest China

The invasive fall armyworm Spodoptera frugiperda(J.E.Smith)invaded Asia in 2018,colonizing the tropical and southern subtropical regions as well as migrating with the monsoons into Northeast Asia during spring and summer.This has resulted in widespread infestations,with significant impacts on maize production in various Asian countries.Previous studies have shown that the invasion of this pest can alter the species relationships of maize pests,but the actual impact on maize pest management is still unclear.This study investigated the changes in maize pest occurrence and pesticide use in the annual breeding areas of S.frugiperda in Yunnan Province and the Guangxi Zhuang Autonomous Region of China during 2017-2021,based on surveys and interviews with small farmers in maize production.The results showed that S.frugiperda has emerged as the dominant species among maize pests after invasion and colonization,replacing traditional pests such as Ostrinia furnacalis,Spodoptera litura,Agrotis ypsilon,and Rhopalosiphum maidis.The variety of pesticides used for maize pest control has changed from chlorpyrifos,lambda-cyhalothrin,and acetamiprid to emamectin benzoate-based pesticides with high effectiveness against S.frugiperda.Furthermore,the frequency of maize pest chemical applications has increased from an average of 5.88 to 7.21 times per season,with the amounts of pesticides used in summer and autumn maize being significantly higher than in winter and spring maize,thereby increasing application costs by more than 35%.The results of this study clarified the impact of S.frugiperda invasion on maize pest community succession and chemical pesticide use in tropical and south subtropical China,thereby providing a baseline for modifying the regional control strategies for maize pests after the invasion of this relatively new pest.