The influence of temperature and light intensity on grain growth in relation to the carbohydrate and nitrogen economy of the wheat plant.

The response of wheat grain growth to temp. and light intensity was studied under controlled conditions within the ranges 10-25 deg C and 64-188 W/m2, resp. Warmth hastened plant senescence and enhanced the initial growth rate of the grains. Additional light promoted the rate of grain growth more at high than at low temp.; under the latter conditions there was a considerable accumulation of carbohydrates in the stem (up to 40%) from anthesis onwards. The rate of grain growth ranged from 0.70 to 1.64 mg/day grain. The duration of grain growth was prolonged by decrease from 25 to 10 deg ; the increase in growth duration from about 30 to 80 days corresponded with a relatively stable temp. sum. Temp. and light also affected the redistribution of assimilates and the chemical composition of the grain. The rate of protein synthesis was promoted more by warmth than the rate of starch synthesis. This resulted in an increased N content of the grain. The final content of total non-structural carbohydrates (starch and sugars) was slightly decreased by warmth. Additional light raised the carbohydrate content of all parts of the plant and so decreased the N content of these parts. However, light intensity had less effect on N distribution and yield than temp. (Abstract retrieved from CAB Abstracts by CABI’s permission

Grain growth and distribution of dry matter in the wheat plant as influenced by temperature, light energy and ear size.

The response of wheat plants during the post-flowering stage to temperature, light intensity and ear size was studied in controlled environments. Within the range 15-25 deg C, increase in temperature increased the growth rate of grains, but the duration of post-flowering development of the plant was very much shortened, with the result that higher temperatures resulted in lower grain yields. Increase in light intensity from 92 to 147 cal/cm2 day had a more positive effect on grain weight than an increase from 147 to 175 cal/cm2 day. Removal of spikelets from the ear increased 1000-grain weight but not sufficiently to compensate for the reduction in the number of grains/ear. (Abstract retrieved from CAB Abstracts by CABI’s permission

Effects of successive applications of maneb and benomyl on growth and yield of five wheat varieties of different heights.

Wheat cv. Juliana (culm length 117 cm), Manella (82 cm), Lely (80 cm), Mex-cross (69 cm) and Gaines (79 cm) were sprayed twice before flowering with 2 kg maneb/ha and twice after flowering with 1 kg benomyl/ha. Combined treatment greatly delayed the spread of Septoria tritici and S. nodorum in the crop, the flag leaf remained green longer, the grain filling period was lengthened, and the growth rate of the grain between the milk stage and the dough stage was increased from 204 to 230 kg/ha day; effects were greater in the susceptible cultivars Lely and Gaines. Increases in grain yield were 14, 23, 32, 16 and 42% for the 5 cultivars, respectively. The green area of the flag leaf accounted for 85% of the variance in grain yield. The degree of disease infection was not significantly correlated with culm length or amount of leaf area. ADDITIONAL ABSTRACT: Spraying with maneb at 2 kg/ha twice before flowering and with benomyl at 1 kg/ha twice after flowering greatly delayed the spread of Septoria tritici and S. [Leptosphaeria] nodorum and increased yields, particularly in the 2 susceptible cvs. (Abstract retrieved from CAB Abstracts by CABI’s permission

Carbon and nutrient stocks of tea plantations differing in age, genotype and plant population density

Tea (Camellia sinensis L.) is a perennial evergreen shrub managed intensively for continuous growth of young shoots. Most tea plantations were established at the expense of native forest. Change in carbon (C) and nutrient (nitrogen, phosphorus, potassium (NPK)) accumulation in forests over time has been intensively studied, but how C and NPK stocks in tea plantations are associated with age, genotype and plant density have not been reported yet in literature. To get a better insight in the effects of age and the associated change in genotype (clone or seedling) and density on C and NPK stocks data were collected in a chronosequence of tea plantations by destructive sampling of whole tea bushes. Four plantations differing in age (76-, 43-, 29- and 14-year old) and genotype¿density combinations were selected. The 76- and 43-year old plantations were composed of seedlings planted at a relative low density: a spacing of 1.52¿×¿0.91 m and 1.22¿×¿1.22 m, respectively, whereas in the 29- and 14-year old plantations an improved clonal cultivar was grown at higher plant densities: a spacing of 1.22¿×¿0.61 m and 1.22¿×¿0.76 m, respectively. Total dry matter weights (DM) of tea bushes increased with age from 9.0 to 11.5 kg in clonal bushes and from 13.5 and 19.9 kg in seedling bushes for the 14- and 29-year, and the 43- and 76-year old plantations, respectively. Most DM was stored in the woody tissue of the tea bush frame. Total C- stocks expressed per unit area (ha) amounted to 44 and 72, and 43 and 69 t C ha¿1 for clonal and seedling bushes, respectively. Total N stocks ranged from 732 to 995 and from 734 to 1,200 kg ha¿1, P stocks from 78 to 120 and from 67 to 92 kg ha¿1, and K stocks from 775 to 901 and from 646 to 1,120 kg ha¿1 for clonal and seedling bushes, respectively. It is concluded that older stands of seedling and clonal tea plantations result in higher C and NPK stocks. Higher stocks may be functional in maintaining yield stability under adverse weather conditions. Plantations with higher nutrient stocks are less responsive to nutrient supply and therefore will require lower fertilizer applications

The effect of light intensity on some morphological and physiological aspects of the crop perennial ryegrass (Lolium perenne L. var. 'Cropper') and its effect on seed production.

Perennial ryegrass cv. Cropper was given high (188), intermediate (140) or low (84 cal/cm2 day between 400-700 nm) light intensity during the period 1 Apr.-30June using supplementary lighting, normal daylight and artificial shading, respectively. Other plots were given 174, 86 and 52 cal/cm2 day during 26 Aug.-1 Oct. and 106, 43 and 26 cal/m2 day until 29 Oct., without affecting the photoperiod. Increased light intensity in autumn or spring considerably increased tillering, while shading treatments gave a decrease. Differences in tiller numbers in autumn decreased during winter and early spring. Numbers of vegetative and reproductive tillers and weight/tiller increased with increasing light intensity in spring. Seed yield was closely correlated with number of reproductive tillers and less closely with number of seeds/head. Supplementary illumination in autumn had only a small effect on number of reproductive tillers but increased number of seeds/head. Maximum LAI of the top 3 leaves, internodes and inflorescences was 13.2, 11.6 and 7.7 in the 3 treatments respectively; these values were high compared with cereals. Amounts of water-soluble carbohydrates in reproductive tillers increased exponentially until ripening and then fell sharply. (Abstract retrieved from CAB Abstracts by CABI’s permission

Grain production and assimilate utilization of wheat in relation to cultivar characteristics, climatic factors and nitrogen supply

The effects on grain production of cultivar characteristics, nitrogen supply and some climatic factors were studied in field trials and under controlled environmental conditions. A rise in temperature considerably increased the rate of grain growth but shortened its duration, whilst the positive effect of light intensity on the grain yield was greater at high temperatures.Additional nitrogen raised post-floral photosynthesis. The nitrogen assimilation by the grains was increased by warmth, resulting in a higher nitrogen concentration of the grains and in earlier senescence of the leaves. Differences between a semi-dwarf cultivar and a standard were mainly expressed in the dry matter distribution before and after anthesis and so in a higher harvest-index

Duurzame landbouw in 2030 en landbouwdoeltypen

Relatie tussen economische, ecologische en sociaal-culturele duurzaamhei