Coordination between plant and apex development in Hordeum vulgare ssp. distichum

Developmental scales for cereals describe apex and plant morphology separately. In order to link crucial steps of internal and external development, in three varieties of Hordeum vulgare spp. distichum L., sown in autumn and in spring, we recorded plant, leaf and apex stage, following the scales of Zadoks, Haun, and Banerjee and Wienhues, the number of primordia, culm and spike length, and the final number of leaves and spikelets. Primordia initiation was coordinated with leaf appearance and the relative rate was constant for the initiation of productive primordia. The maximum number of primordia was achieved just before the first node became detectable, but development was completed only by those initiated before floret differentiation and internode distension started. The first spikelet was initiated when the third leaf tip became visible, and the last one when plants were at the pseudo stem erection stage and five leaves had still to appear

Nitrogen and phosphorus accumulation and remobilization of durum wheat as affected by soil gravel content

Soil gravel content affects many soil physical properties, as well as crop yield. Little is known regarding the influence of soil gravel content on growth and nutrient uptake of durum wheat (Triticum durum Desf.). The accumulation of nitrogen and phosphorous during the vegetative and reproductive periods and the contribution of pre-anthesis assimilates to grain N and P con- tent have been evaluated in two durum wheat varieties grown on soils with 0, 10, 20 and 30% gravel content. The two varieties showed similar behaviour and the increase of soil gravel de- creased plant biomass during the entire biological cycle. Nitrogen and P concentration of all plant parts was not affected by soil gravel content, while N and P content was greatly reduced, owing to the effect on dry matter yield. Post-anthesis accumulation and remobilization of N and P were greatly reduced: the decrease from gravel-free soil to 30% gravel content was about 41 kg N ha–1 and 4 kg P ha–1 for the former and 14 kg N ha–1 and 2 kg P ha–1 for the latter. The differences in growth rate were attributed to differences in development of the root system due to the restricted soil volume

Post-anthesis accumulation and remobilization of dry matter, nitrogen and phosphorus in durum wheat as affected by soil type

The objective of the research was to quantify the changes in the accumulation of dry matter and N and P content of four durum wheat (Triticum durum Desf.) varieties grown on two soil types (sandy-loam and clay-loam), differing for texture, nitrogen content and water holding capacity. Plants were grown in containers and were rainfed until anthesis; irrigation was performed during grain filling to avoid water stress. The difference in total vegetative weight and nitrogen and phosphorus content of plants between anthesis and maturity was used to indirectly estimate the relative contribution of pre-anthesis assimilation and remobilization to grain yield. The behaviour of the four varieties was similar as they ranked in the same order for pre-anthesis and post-anthesis dry matter accumulation and grain yield and differences in soil characteristics induced similar changes in dry matter, N and P accumulation and remobilization. Soil type greatly affected the patterns of dry matter, N and P accumulation and remobilization. Plants grown on clay-loam soil had higher dry weight and N and P content both at anthesis and at maturity and higher grain yield at maturity, compared to plants grown on sandy-loam soil and the remobilization of dry matter, N and P were 75, 140 and 55% higher. Most of the grain carbohydrates originated from photosynthates produced during grain fill, as the contribution of remobilization of dry matter to grain yield did not reach 30%, while most of the grain N and P originated from the remobilization of N and P accumulated prior to anthesis as remobilization of N accounted for 73–82% of grain N content and remobilization of P accounted for 56–63% of grain P content

Above- and below-ground competition between barley, wheat, lupin and vetch in a cereal and legume intercropping system

The effects of intercropping on dry weight (DW) of herbage and nitrogen (N) nutrition of plants of two winter cereals, barley and wheat, and two legumes, white lupin and common vetch, were investigated, and above- and below-ground competition were separated in a fully factorial additive design. Intercropping increased DW compared with the sole species and the increase was higher for the cereals and lupin than for cereals and vetch intercropping systems. Above-ground competition for light reduced DW of cereals and lupin while it did not influence the DW of vetch. Processes involved in below-ground competition increased shoot growth of cereals and reduced shoot growth of legumes. N nutrition of cereals was enhanced by below-ground competition with legumes and N nutrition of vetch was enhanced by above-ground competition with cereals. Cereals had a higher competitive ability than legumes as a result of their below-ground competitive ability. The interaction between above- and below-competition is not predictable: negative, positive and no interaction (additivity) between different types of competition were found. In low-input intercropping systems, when a N-fixing species is present, the mixture of the roots of components is important for the utilization of the soil resources and, when a climbing species is also present, the mixture of shoots can result in an increased utilization of light