Demonstration of targeted crossovers in hybrid maize using CRISPR technology

Naturally occurring chromosomal crossovers (CO) during meiosis are a key driver of genetic diversity. The ability to target CO at specific allelic loci in hybrid plants would provide an advantage to the plant breeding process by facilitating trait introgression, and potentially increasing the rate of genetic gain. We present the first demonstration of targeted CO in hybrid maize utilizing the CRISPR Cas12a system. Our experiments showed that stable and heritable targeted CO can be produced in F1 somatic cells using Cas12a at a significantly higher rate than the natural CO in the same interval. Molecular characterization of the recombinant plants demonstrated that the targeted CO were driven by the non-homologous end joining (NHEJ) or HDR repair pathways, presumably during the mitotic cell cycle. These results are a step towards the use of RNA-guided nuclease technology to simplify the creation of targeted genome combinations in progeny and accelerate breeding.

Nutritional comparison between hydroponically grown leguminous and non-leguminous fodder to identify the adaptability and best harvesting time for sustainable hydroponic grass production

Two types of fodder crops were evaluated in this study, maize (Zia maize) and black gram (BG) (Vigna mungo) and in maize, non-descriptive local maize (LM) and hybrid maize (HM) verity were used. LM was considered as control and changes of the nutritional composition according to the type of fodder (leguminous and non-leguminous) and the day was evaluated. For comparative nutritional analysis, dry matter (DM), crude protein (CP), ether extract (EE), crude fibre (CF), acid detergent fibre (ADF), neutral detergent fibre (NDF), and total ash were analyzed and the biomass yield was measured using weight balance and root and shoot length of experimental fodders. Results revealed that among three types of forages total DM was significantly (P<0.01) higher in HM and significantly (P<0.01) lower in BG. Considering total CP and NDF, it was significantly (P<0.01) higher in BG and HM than LM. The highest biomass yield and shoot length were observed in BG and the lowest biomass yield was observed in HM. Moreover, with the increment of days, all fodder sprouts DM% was constantly decreasing, however, CP% maintained the same level from day 1 to 5. Although from day 6 to 9, CP% increased moderately for HM and BG, CP% decreased slightly for LM. Therefore, farmer can use BG and HM for maximum utilization of nutrients and considering DM and CP% for LM day 6 was the best time for harvesting; however, for HM and BG, day 9 or more than 9 was the best time for harvesting. Res. Agric., Livest. Fish.8(3): 321-328, December 2021

Growth and yields of two varieties of maize (Zea mays L.) intercropped with peanut (Arachys hypogaea L.) applied by bokashi plus fertilizer between the rows of teak trees based agroforestry system

Nutrient shortages are the main problems faced by farmers, so as to improve soil fertility using organic fertilizer is compulsory. The main objective was to analyze the effects of bokashi plus fertilizer on the growth and yields of two varieties of maize intercropped with peanut under three years old teak trees in agroforestry system. The research was arranged in randomized completely block design in factorial pattern with two factors, maize variety: local maize and hybrid corn bisi-2; and bokashi plus fertilizer doses: 0, 3, 6 and 9 t ha-1. Maize growth recorded were plant height, leaf number, stem diameter and leaf area at 2, 4, 6 and 8 WAP and maize yields recorded were cob weight with cornhusk, cob weight without cornhusk, cob length, diameter, row number, 100 seeds dry weight, biomass dry weight, yield and LER. The results showed that interaction between maize variety and bokashi plus fertilizer had significant effect on the growth and yield of maize intercropped with peanut under three years of teak trees in agroforestry system. The best effects of maize growth and yield were obtained at 9 t ha-1 with highest yield of local maize and hybrid maize of 4,69 and 5,79 t ha-1.

Nutrient Use Efficiency Indices in Maize Hybrid as A Function of Various Rates of NPK in Mid Hills of Nepal

Field experiments were conducted to evaluate yield and nutrient use efficiency in maize in response to various rates of nitrogen (N), phosphorus (P) and potassium (K) in silty clay loam soil of Khumaltar, Nepal during 2019 and 2020. Three factorial randomized complete block designs with 27 treatment combinations were used in experiments, which were repeated three times. Three factors were N levels (150, 180, 210 N kg ha-1), P levels (40, 60, 80 P2O5 kg ha-1), and K levels (40, 60, 80 K2O kg ha-1). The results recommend to revise fertilizer dose since N210 kg ha-1 and K2O 80 kg/ha were optimum for increased maize production with grain yields of 10.95 t ha-1 and 10.54 t ha-1, respectively. Partial factor productivity, partial nutrient budget, internal efficiency, physiological efficiency, recovery efficiency, and agronomic efficiency of NPK for hybrid maize were mostly influenced by nutrient levels. Application of higher rate of P and K fertilizer improved maize N efficiencies, and case was valid for P and K efficiencies. Maize was more responsive to N and K fertilizer and lower rate of P application limited efficient use of applied N and K. To increase overall NUE, we recommend to revise dose of fertilizer for hybrid maize under mid hill condition of Nepal.

Fertilizer Effects on Endosperm Physicochemical Properties and Resistance to Larger Grain Borer, Prostephanus truncatus (Coleoptera: Bostrichidae), in Malawian Local Maize (Zea mays L.) Varieties: Potential for Utilization of Ca and Mg Nutrition

Maize grain hardness influences storage pest resistance, a key characteristic valued by smallholder farmers. The structural changes in the endosperm determine grain hardness and are influenced by agronomic practices. The purpose of this study was to establish whether supply of calcium and magnesium based fertilizers can alter physicochemical properties of local and hybrid maize varieties and reduce the infestation by larger grain borer (Prostephanus truncatus (Coleoptera: Bostrichidae)) during storage. Two local and one hybrid maize varieties commonly grown by smallholder farmers in Malawi were cultivated under three fertilizer treatments (NPK (nitrogen, phosphorous, potassium), NPK plus gypsum, and NPK plus dolomite). After harvest, the grains were classified into flint and dent types, followed by P. truncatus infestation and determination of their physicochemical properties. The addition of gypsum and dolomite fertilizers led to higher levels of amylose, total zein and β-14 zein, traits associated with kernel hardness, compared to the application of NPK fertilizer. Moreover, local maize varieties showed higher resistance to P. truncatus infestation, hardness and biochemical properties associated with hardness (total zein, α-19 and β-14 zein, starch lysophosphatidylcholine, and non-starch free fatty acid) compared to hybrid variety. Our study suggests the potential for utilizing Ca and Mg nutrition in maize to improve kernel hardness, thus adoption of gypsum and dolomite by smallholder farmers may be beneficial against P. truncatus during storage.

Multivariate and Association Analysis for Yield and Yield Attributing Traits in Quality Protein Maize (QPM) Inbred Lines

The present investigation reveals the diversity existing among thirty inbred lines of Quality Protein Maize (QPM) in terms of yield and yield attributing traits. The study further elucidates the mutual association among the various morphological traits recorded among the inbred lines. The inbred lines were evaluated during the Rabi seasons of 2016-17, 2017-18 and 2018-19. The analysis of variance calculated over the mean performances of the inbred lines across three rabi seasons revealed significant differences among the inbred lines in terms of yield and yield attributing traits. The diversity among the inbred lines were further determined using cluster analysis which classified the inbred lines into 3 phylogenetically distinct groups. Additionally, a principal component analysis was performed which revealed three principal components (i.e., PC I, II and III) elucidating eighty six percent of the total observable variance among the inbred lines, with traits like grain yield, cob length, cob diameter, number of grain rows per cob, number of grains per row and number of grains per cob contributing to nearly half of the total variance explained by the Principal Component Analysis (PCA). The correlation as well as path coefficient analysis performed for the various traits further indicated significant influence of morphological traits like cob length, cob diameter, number of grain rows per cob and number of grains per cob over the observable grain yield per plant. Overall, the observations from the current investigation can be helpful in identifying superior parental lines to be used in future hybrid maize development programs.

Influence of different sowing density in two varieties of maize. Part II. Relation to agricultural morphological features

Summary In this paper, we investigate the effect of seeding density on several morphological features such as plant height, height of the production ears, ear length, ear diameter, leaf area, and LAI (leaf area index). Inference is based on a series of three-year two-factor experiments with two hybrid maize varieties – SY Cooky and Drim “stay-green” type – and 5 sowing densities: 6, 7, 8, 9 and 10 plants per m2. The “stay-green” maize variety had production cobs significantly higher on the plant, and had a thicker cob and a larger leaf assimilation area than the conventional variety. Increasing maize sowing density from 6 to 10 plants m−2 resulted in a linear decrease in cob length and diameter, while it increased the LAI. Significantly higher chlorophyll content, expressed in SPAD units, was found in the “stay-green” hybrid at the BBCH 67 stage in a wet (2012) and drier year (2014), compared with the traditional variety. This may indicate that such a variety is more tolerant to stress conditions.

Why farmers use so many different maize varieties in West Kenya

In this article we reflect on the discussions as to whether breeding and seed system development should proceed along its current well established route of developing varieties with a higher agricultural productivity or if the diversity of farmers, their contexts and rationales requires broader approaches. We make use of data from a recently held survey (2018) in West Kenya. The data show that some 80% of the households in the survey planted both local and hybrid maize varieties. The choices that people make about which variety to plant are many. Apart from rainfall, the availability of cash, the promise of a good yield, the presence of projects and programs and the culture of seed also influences these choices. We argue that an inclusive demand-oriented maize breeding and seed system needs to include a range of varieties and seed sources and to develop and support different delivery pathways to fit farmers’ diverse use of seeds and varieties. Our findings also indicate the need for more systematic study of the diversity of farmers’ rationales and the performance of crop varieties. This would provide useful information for all the actors involved.

REDIPLOID MAIZE LINES: (RESYNTHESIZED FROM A TETRAPLOID POPULATION FOR BREEDING HYBRID MAIZE)

The catalogue was compiled based on the results of studying the breeding value of 200 accessions of rediploid lines isolated from tetraploid maize populations with a description of 37 morphological traits, which have economic and breeding importance. The catalogue is addressed to geneticists, breeders and agronomists to be used as a starting material for breeding hybrid forage and food maize in the Russian Federation.