Recurrent Selection for Maize Grain Yield: Dry Matter and Nitrogen Accumulation and Partitioning Changes

Abstract

Recurrent full‐sib family and reciprocal recurrent selection have resulted in significant increases in grain weight of crosses between the varieties of maize (Zea mays L.) Jarvis Golden Prolific and Indian Chief. The objectives of this study were to (i) compare increases due to 14 cycles of recurrent full‐sib family selection, and reciprocal recurrent selection for yield in maize and (ii) determine whether increased grain weights were accompanied by parallel increases in total dry matter and total N accumulation. Unless total dry matter acquisition increases in parallel with grain weight during selection, sustained root and shoot functions would be restricted by excessive diversion of carbohydrates to grain. After 14 selection cycles on sandy soils of the North Carolina coastal plain, grain weight, dry matter accumulation, and N accumulation in the population hybrid increased 23, 12, and 4%, respectively, with full‐sib family selection and 27, 21, and I0%, respectively, with reciprocal recurrent selection. Greater proportions of the dry matter and N accumulated were partitioned to grain after full‐sib family selection than after reciprocal recurrent selection. Therefore, photosynthate production after full‐sib family selection was not sufficient to fully satisfy both the demand by grain and the requirements for root and shoot processes. Reciprocal recurrent selection resulted in a greater increase in photosynthate production, so that the hybrid population was able to meet the demand for carbohydrate by higher grain yield and still sustain N acquisition by roots. The conclusions were also supported by heterosis for grain weight, total dry matter, and total N accumulation, which was greater after reciprocal recurrent selection than after full‐sib family selection. Selection to increase grain weight will result in efficient N acquisition only when the greater grain weight is supported by an adequate increase in photosynthate production.

Response of Maize Grown Under High Plant Density; Performance, Issues and Management - A Critical Review

“…Various stresses, including nitrogen deprivation and inter-plant competition by high plant density decreased ear size and kernel row number, as well as kernel set in maize and reduced yield [55]. Increased N supply, increased accumulation of dry matter and N by aboveground plant parts of corn during grain filling and ultimately increased yields [56,57] whereas low-yielding maize hybrids responded poorly to added N [58]. Nitrogen fertilization affected corn dry matter (DM) production by influencing leaf area development, leaf area maintenance and photosynthetic efficiency of the leaf area [59] and maximum economic DM for corn occurred at an N rate of about 150 kgha -1 [60].…”

Adubação nitrogenada em milho pelo monitoramento do nível de nitrogênio na planta por meio do clorofilômetro

“…Segundo estes autores, a continuidade de absorção de N durante o período de enchimento de grãos implica menor remobilização deste nutriente de órgãos vegetativos, resultando em aumento da duração da área foliar e prolongamento do período de acúmulo de matéria seca. Estas duas caracterís-ticas são importantes, pois estão associadas a altos rendimentos de grãos de milho (Moll et al, 1994).…”

Changes in the rate of photosynthesis accompanying the yield increase in wheat cultivars released in the past 50�years

“…However, there have been quite contradictory conclusions over the function of the most important physiological trait, photosynthetic rate. Many authors believe that there has been no change in the rate of photosynthesis (per unit leaf area, usually measured on flag leaves) to accompany the grain yield increases; even a negative relation between photosynthesis and grain yield has been reported (Evans 1993;Moll et al 1994;Reynolds et al 2000;Richards 2000). Sharply contrasting with this, positive correlations of the two traits have also been found (Puckridge 1971;Peng et al 1991;Jiang et al 2000).…”

“…Investigations of agronomic improvement to increase wheat yield potentials have been well documented (for a review, see Richards 2000). In respect of botanical features, the kernel number (Brocklehurst 1977;Moll et al 1994;Richards 1996;Rajcan and Tollenaar 1999a, b) has been increased. The study of ultrastructure of chloroplasts is helpful for understanding the formation of photosynthate production in wheat (Zuo et al 1994).…”