Grain yield in maize is the result of a genotype's response to environmental conditions a... more Grain yield in maize is the result of a genotype's response to environmental conditions and agronomic management. However, whether in a field, greenhouse, or growth chamber, plant-to-plant variation exists within the same genotype, necessitating large amounts of plants and growth area to determine a metabolic response to a change in growth conditions or fertilizer supply. Additionally, because of whole-plant interactions in the supply of nutrients to kernels, it is difficult to study assimilate or temperature effects on the growth of kernels. The in vitro growth of kernels is one way to circumvent this problem because it allows for kernel growth under defined conditions of nutrient supply, while minimizing environmental and maternal influences. The in vitro kernel culturing method can be used to identify source: sink relationships, assimilate transport, metabolism, plant growth regulators, and other physiological responses by altering the source supply to individual kernels within an ear, thereby reducing or controlling environmental effects, while maintaining kernel-cob and organ-wide interactions. A single control-pollinated immature maize ear can be divided and quickly subjected to various growth conditions using liquid media to more precisely generate physiological and metabolic changes in the earshoot than in planta.
An improved technique for long-term culture of rice caryopses is necessary for physiological and ... more An improved technique for long-term culture of rice caryopses is necessary for physiological and genetic studies. Panicles of three rice (Oryza sativa) cultivars `Lemont', `Gummo-byeu' and `Hwasung-byeu' were cultured in liquid media with combinations of light versus dark, panicle position, nitrogen level (5-40 mM), and sucrose level (29–351 mM). Grain growth was increased when panicles were positioned horizontally, partially submerged
Direct-seeding has major advantages such as labor and cost saving by eliminating preparation of s... more Direct-seeding has major advantages such as labor and cost saving by eliminating preparation of seed bed and transplanting. But, it required increased input of fertilizers and pesticides because of the extended paddy period. Direct seeding in wet paddy (DSWP) gives faster growth and more uniform seedling emergence than direct-seeding in dry paddy. This research had an objective to develop an efficient N management practices for DSWP with split application of N fertilizer. A paddy field experiment was conducted to evaluate effects of starter N and N-topdressing which was delayed N application until 5-leaf stage, with comparison to transplanting (TP). Total amount of N application were two levels; 110kg and 77kg/ha. The N applications were split four times during rice growth stages; starter, topdressing at 5-leaf stage, top dressing at tillering stage, and topdressing at panicle initiation stage. DSWP had more tillers/ than TP, but with the delayed heading. The DSWP plots which receiv...
This study was conducted to determine the relationship between nitrate reductase activity (NRA) a... more This study was conducted to determine the relationship between nitrate reductase activity (NRA) and reduced N, N harvest index, N uptake, N utilization, N-use efficiency and grain N accumulation of maize. Eight cycles of divergent phenotypic recurrent selection for high and low levels of postanthesis leaf-lamina NRA were completed in the maize synthetic Super Stiff Stalk. Selection for high NRA had little effect on the N traits evaluated. In contrast, selection for low NRA resulted in significant reductions for many of the N traits examined. Selection for low NRA has adversely affected nitrate metabolism in this population, resulting in lower grain N production and less-efficient use of soil-applied N to produce grain
Continued yield increases of maize (Zea mays L.) will require higher planting populations, and en... more Continued yield increases of maize (Zea mays L.) will require higher planting populations, and enhancement of other agronomic inputs could alleviate density-induced stress. Row spacing, plant population, P-S-Zn fertility, K-B fertility, N fertility, and foliar protection were evaluated for their individual and cumulative impacts on the productivity of maize in a maize-soybean [Glycine max (L.) Merr.] rotation. An incomplete factorial design with these agronomic factors in both 0.76 and 0.51 m row widths was implemented for 13 trials in Illinois, United States, from 2014 to 2018. The agronomic treatments were compared to two controls: enhanced and standard, comprising all the factors applied at the enhanced or standard level, respectively. The 0.51 m enhanced management control yielded 3.3 Mg ha–1 (1.8–4.6 Mg ha–1 across the environments) more grain (25%) than the 0.76 m standard management control, demonstrating the apparent yield gap between traditional farm practices and attainabl...
Grain yield in maize is the result of a genotype's response to environmental conditions a... more Grain yield in maize is the result of a genotype's response to environmental conditions and agronomic management. However, whether in a field, greenhouse, or growth chamber, plant-to-plant variation exists within the same genotype, necessitating large amounts of plants and growth area to determine a metabolic response to a change in growth conditions or fertilizer supply. Additionally, because of whole-plant interactions in the supply of nutrients to kernels, it is difficult to study assimilate or temperature effects on the growth of kernels. The in vitro growth of kernels is one way to circumvent this problem because it allows for kernel growth under defined conditions of nutrient supply, while minimizing environmental and maternal influences. The in vitro kernel culturing method can be used to identify source: sink relationships, assimilate transport, metabolism, plant growth regulators, and other physiological responses by altering the source supply to individual kernels within an ear, thereby reducing or controlling environmental effects, while maintaining kernel-cob and organ-wide interactions. A single control-pollinated immature maize ear can be divided and quickly subjected to various growth conditions using liquid media to more precisely generate physiological and metabolic changes in the earshoot than in planta.
An improved technique for long-term culture of rice caryopses is necessary for physiological and ... more An improved technique for long-term culture of rice caryopses is necessary for physiological and genetic studies. Panicles of three rice (Oryza sativa) cultivars `Lemont', `Gummo-byeu' and `Hwasung-byeu' were cultured in liquid media with combinations of light versus dark, panicle position, nitrogen level (5-40 mM), and sucrose level (29–351 mM). Grain growth was increased when panicles were positioned horizontally, partially submerged
Direct-seeding has major advantages such as labor and cost saving by eliminating preparation of s... more Direct-seeding has major advantages such as labor and cost saving by eliminating preparation of seed bed and transplanting. But, it required increased input of fertilizers and pesticides because of the extended paddy period. Direct seeding in wet paddy (DSWP) gives faster growth and more uniform seedling emergence than direct-seeding in dry paddy. This research had an objective to develop an efficient N management practices for DSWP with split application of N fertilizer. A paddy field experiment was conducted to evaluate effects of starter N and N-topdressing which was delayed N application until 5-leaf stage, with comparison to transplanting (TP). Total amount of N application were two levels; 110kg and 77kg/ha. The N applications were split four times during rice growth stages; starter, topdressing at 5-leaf stage, top dressing at tillering stage, and topdressing at panicle initiation stage. DSWP had more tillers/ than TP, but with the delayed heading. The DSWP plots which receiv...
This study was conducted to determine the relationship between nitrate reductase activity (NRA) a... more This study was conducted to determine the relationship between nitrate reductase activity (NRA) and reduced N, N harvest index, N uptake, N utilization, N-use efficiency and grain N accumulation of maize. Eight cycles of divergent phenotypic recurrent selection for high and low levels of postanthesis leaf-lamina NRA were completed in the maize synthetic Super Stiff Stalk. Selection for high NRA had little effect on the N traits evaluated. In contrast, selection for low NRA resulted in significant reductions for many of the N traits examined. Selection for low NRA has adversely affected nitrate metabolism in this population, resulting in lower grain N production and less-efficient use of soil-applied N to produce grain
Continued yield increases of maize (Zea mays L.) will require higher planting populations, and en... more Continued yield increases of maize (Zea mays L.) will require higher planting populations, and enhancement of other agronomic inputs could alleviate density-induced stress. Row spacing, plant population, P-S-Zn fertility, K-B fertility, N fertility, and foliar protection were evaluated for their individual and cumulative impacts on the productivity of maize in a maize-soybean [Glycine max (L.) Merr.] rotation. An incomplete factorial design with these agronomic factors in both 0.76 and 0.51 m row widths was implemented for 13 trials in Illinois, United States, from 2014 to 2018. The agronomic treatments were compared to two controls: enhanced and standard, comprising all the factors applied at the enhanced or standard level, respectively. The 0.51 m enhanced management control yielded 3.3 Mg ha–1 (1.8–4.6 Mg ha–1 across the environments) more grain (25%) than the 0.76 m standard management control, demonstrating the apparent yield gap between traditional farm practices and attainabl...
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