Latest Research News on Corn Genotypes: Feb 2021
Root Characteristics of Corn Genotypes as Related to P Uptake
Plant utilization of P applied to soils is usually low. Utilization may be increased by having more roots present or by improving P uptake characteristics of the roots. The objective of this research was to determine the effect of varying corn (Zea mays L.) root characteristics, by using different genotypes, on P uptake and to determine if the Claassen‐Barber simulation model predicted these differences accurately. Five corn genotypes were grown in the growth chamber in soil at two levels of P and harvested a three ages. Increasing P level increased shoot yield of all genotypes, but had little effect on the amount of roots. The root surface area per unit of shoot weight varied between genotypes at low soil P but not at high soil P. Wih high soil P here was a linear correlation with r = 0.98 and a slope of 0.97 between P uptake predicted by the simulation model and observed P uptake. At low soil P observed P uptake was double the predicted uptake, however, the correlation was r = 0.90. Root hair effects, not included in the simulation model, were probably the reason for the greater observed P uptake at low soil P. Differences between genotype in morphological and physiological root characteristics in. fluenced the amount of P absorbed by corn plants. It appears that genotypes could be developed that would be more efficient in absorbing P from soil. 
Effect of Nitrogen on Root Growth of Two Corn Genotypes in the Field
Corn (Zea mays L.) genotypes vary in their response to applied N fertilizer. Nitrogen uptake by the plant is controlled by N influx at the root surface and the size and morphology of the root system. The objective of this study was to investigate the effect of applied N on mean N influx and root growth of two genotypes that differed in their response to N. Nitrogen rates were 0 and 227 kg ha−1 for ‘Pioneer 3732’ and ‘B73✕Mo17’ grown on Raub silt loam (Aquic Argiudolls) and 227 kg N ha−1 on Chalmers silt loam (Typic Haplaquolls). Root growth, plant weight, and N content were measured 31,47,61,75,91 and 109 days after planting. Apart from an initial difference at 31 days, mean N influx of roots of both genotypes were similar. Root length and root surface area of Pioneer 3732 were not increased by the application of N. In contrast, applied N increased root growth of B73✕Mo17. By midsilk (75 days) root length of B73✕Mo17 was 36 and 39% greater than that of Pioneer 3732 on the Raub and Chalmers soils, respectively, to which N was applied. The greater root growth of B73✕Mo17 and the continued root growth of this hybrid after midsilk appears to be one possible mechanism to explain the greater growth of this hybrid under a high‐N fertilizer regime. This requires further verification under a wider range of environmental conditions. A lack of moisture limited the grain yields of both hybrids in this study. 
Standard Ear Yield and Some Agronomic Characteristics of Baby Corn var. ksc 403 su under Influence of Planting Date and Plant Density
In order to investigate of standard ear yield and some agronomic characteristics of baby corn under influence of planting date and plant density an experiment was conducted at Khorasan Razavi Agricultural and Natural Resources Research center, Mashhad, Iran in 2010. In this research planting date (14 June, 3 July and 24 July) and plant densities (65000, 85000 and 105000 plant ha-1) were arranged in main and sub plots, respectively. This experiment was laid out using a split plot design with four replications. The results indicated that different planting dates had significant effects on agronomic traits such as plant height, ear height, number of leaves above ear, stem diameter, ear length, and ear diameter, dehusked and husked baby corn yield, standard and sub-standard dehusked ear yield, standard and sub-standard ear percentage. The highest husked ear yield with 13240 kg ha-1 was belonged to 24 July planting date. Although, delay in planting date, led to increase of growth period prevail suitable weather (low temperatures) at anthesis, therefore, ear yield increased but caused to the reduction of ear length and increased ear diameter. Also, ear marketing obviously decreased, not only for fresh consumption but also for industry. The highest dehusked standard ear yield (722 kg ha-1) was obtained from the highest plant density. Interaction effect of planting date × plant density had significant on standard ear percentage at a 5% level of probability. Finally, planting date of 14 June and the highest planting density of 105000 plant ha-1, is recommended in order to maximize and produce high quality standard ear that can be presentable in market. 
Maximizing Maize (Zea mays L.) Crop Yield via Matching the Appropriate Genotype with the Optimum Plant Density
Aim: The objective of this investigation was to match the functions of optimum plant density to produce the highest possible grain yield per unit area with the greatest maize genotype efficiency.
Study Design: A split plot design in randomized complete block arrangement was used with three replications. The main plots were assigned to plant densities, and sub-plots to maize genotypes.
Place and Duration of Study: This study was carried out at the Agricultural Experiment and Research Station of the Faculty of Agriculture, Cairo University, Giza, Egypt in 2012, 2013 and 2014 seasons.
Methodology: Six maize inbred lines differing in tolerance to high density (D) [three tolerant (T); L-20, L-53, Sk-5, and three sensitive (S); L-18, L-28, Sd-7] were chosen for diallel crosses. Parents and hybrids were evaluated under three plant densities: low (47,600), medium (71,400), and high (95,200) plants ha-1.
Results: The T×T hybrids were superior to the S×S and T×S hybrids under the high D in most studied traits across seasons. The relationships between the three densities and grain yield per hectare (GYPH) showed near-linear regression functions of increase for inbreds L-53, L-28, Sk-5 and Sd-7 and efficient non-responsive and inefficient responsive groups of hybrids with the optimum density of 95,200 plants ha-1, near-linear regression of increase for inbred L-18 with optimum density of 47,600 plants ha-1 and a curvilinear relationship for inbred L20 and the rest of the hybrids with the optimum density of 95,200 plants ha-1 for in-efficient non-responsive crosses and 88,000 plants ha-1 for inbred L20 and efficient responsive hybrids.
Conclusion: Growing the tolerant hybrid L20×L53 under high-D gave the highest grain yield (17.05 t ha-1) in this study with a superiority to the best check (SC 2055) of 27.0%. 
Potassium and phosphorus uptake by corn genotypes grown in the field as influenced by root characteristics
Root parameters of three corn (Zea mays L.) genotypes influencing P and K uptake were investigated in solution culture and field experiments. The data for these parameters were used to simulate P and K uptake by plants grown in the field using the Claassen-Barber model5. Root characteristics for ion influx, maximum rate of influx,Imax; Michaelis-Menten constant,Km; and minimum concentration of solution below which no further net influx occurs,Cmin were determined in solution culture. These kinetic parameters varied 2 to 3 fold among genotypes. Variations among genotypes were different for K than for P. 
 Schenk, M.K. and Barber, S.A., 1979. Root characteristics of corn genotypes as related to p uptake 1. Agronomy Journal, 71(6), pp.921-924.
 Mackay, A.D. and Barber, S.A., 1986. Effect of Nitrogen on Root Growth of Two Corn Genotypes in the Field 1. Agronomy Journal, 78(4), pp.699-703.
 Rahmani, A., Alhossini, M. and Kalat, S. M. (2014) “Standard Ear Yield and Some Agronomic Characteristics of Baby Corn var. ksc 403 su under Influence of Planting Date and Plant Density”, Journal of Experimental Agriculture International, 6(2), pp. 104-111. doi: 10.9734/AJEA/2015/13832.
 M. M. Al-Naggar, A., M. M. Atta, M., A. Ahmed, M. and S. M. Younis, A. (2016) “Maximizing Maize (Zea mays L.) Crop Yield via Matching the Appropriate Genotype with the Optimum Plant Density”, Journal of Applied Life Sciences International, 5(4), pp. 1-18. doi: 10.9734/JALSI/2016/26811.
 Schenk, M.K. and Barber, S.A., 1980. Potassium and phosphorus uptake by corn genotypes grown in the field as influenced by root characteristics. Plant and Soil, 54(1), pp.65-76.