Crop Management Effects on Pre‐and Post‐Anthesis Changes in Leaf Area Index and Leaf Area Duration and their Contribution to Grain Yield and Yield Components in Spring Cereals

Abstract

Seasonal changes in leaf area index (LAI) and leaf area duration (LAD, i.e. LAI integrated over cumulated degree days) have a marked effect on crop productivity. Three case experiments were conducted at Suitia (60°irN) and Viikki (60'13'N) Experimental Farms, University of Helsinki, Finland, to evaluate the possibilities of accelerating pre-anthesis expansion of leaf area and modifying pre-and post-anthesis LAD in spring cereals through crop management. Effects of time of incorporation of a green manure crop residue into the soil [conventional tillage (autumn ploughing and seed bed preparation in the spring), conservation tillage (sole spring tillage) with and without a green manure crop, common vetch {Vicia sativa l.)]and N fertilizer rate (0, 50, 100 kg N ha ') on LAI and pre-and post-anthesis LAD in wheat {Triticum aestivum L.) were studied in exp I; green manuring (common vetch) and N fertilizer rate (0,40, 70, 110, 150 kg N ha^') in barley {Hordeum vulgare L.), oat {Avena sativa L.), and wheat in exp II; and fohar application of chlormequat chloride (CCC) and ethephon in oat lines (dwarf, naked, modern, landrace) differing in canopy structure in exp III. Time of incorporation of the green manure crop residues into the soil (exp I), green manuring (exp II), N fertilizer rate (exps I and II), and selection for crop growth type (exp III), but not CCC and ethephon, modified LAI and LAD in spring cereals by affecting the rate of pre-anthesis expansion and postanthesis reduction in leaf area rather than by markedly prolonging the growth period. High rates of N fertilizer accelerated expansion of leaf area, especially prior to stem elongation, and resulted in high pre-anthesis LAD due to enhanced tiller growth (exps I and II) and more tillers per main shoot (exp I). Green manuring increased leaf expansion from the tillering stage most when combined with high N rate, and especially in barley (exp II), but no such effects were found in exp I. Use of a high N fertilizer rate (exps I and 11) and green manuring (exp II) also resulted in high post-anthesis LAD. Such modifications enabled higher rates of grain-and head-filling. and in exp 1 contributed to increased head weight and grain yield. Selection for inherent differences in growth type provided an additional possibility for manipulation of canopy structure and yield fonnation.

Photosynthetic productivity of two winter wheat varieties (Triticum aestivum L.)

“…concentration of N and Mg during the tillering stage (stage 2) at both locations and in both years. However, different mineral nutrition and climate conditions at both locations had an impact on element assimilation and the obtained results were in accordance with many authors who emphasised the importance of N in wheat nutrition (Cox et al 1985, Sariae et al 1986, Vukadinoviae and Tekliae 1988, Osaki et al 1991, Schadchina and Dimitreva 1995, Frederick 1997, Peltonen-Sainio et al 1997. As vegetation advanced N concentration decreased and dry matter content increased, which was the result of plant growth and photosynthesis (Tables 3 and 4).…”

“…In order to attain high yield it is important to ensure photosynthetic rate by leaf area index (LAI) maintenance until late wheat maturity stage (Osaki et al 1991). Increase of spring nitrogen top dressing leads to LAI increase that in turns slows down leaf area loss (Frederick 1997) followed by later wheat maturity (Peltonen-Sainio et al 1997). Chatterjee et al (1994) indicated that Mg excess in wheat plants resulted in visible Mn deficit symptoms whereas dry matter, chloroplast pigments content, grain yield etc.…”

Leaf area duration of oilseed rape (Brassica napus subsp. napus) varieties and hybrids and its relationship to selected growth and productivity parameters

“…Seasonal changes in LAI and LAD have a marked effect on crop productivity [13]. LAD displayed a strong positive correlation with both dry matter production and grain yield [11].…”

Characterising strengths, weaknesses, opportunities and threats in producing naked oat as a novel crop for northern growing conditions

“…Rapid establishment in association with early and full ground coverage is targeted also in naked oat. Under northern growing conditions 46% of variation in grain yield, 71% for panicle weight, 76% for number of grains per panicle, and 71% for panicle filling rate in oat, including the naked type, was attributed to pre-anthesis leaf area duration (LAD), a trait that takes into account both green area and its persistence (Peltonen-Sainio 1997b, Peltonen-Sainio et al 1997.…”