Physiological determinants of maize and sunflower grain yield as affected by nitrogen supply

Utilisation of nitrogen (N) has been closely related to increases in crop productivity. However, not all crops respond similarly and the objective of this study is to identify physiological processes that determine responses to N supply for maize and sunflower. Grain yield in maize (range: 210–1255 g m⁻²) was greater and more responsive to N supply than in sunflower (106–555 g m⁻² in carbohydrate equivalents) over a wide range of total N uptake (3–>20 g N m⁻²). In maize, differences in grain yield among levels of N supply were associated more with variation in biomass than in harvest index. In sunflower, differences in grain yield (in carbohydrate equivalents) among levels of N supply were related similarly to variation in both biomass and harvest index. The decrease in biomass production with decreasing N supply was associated with decreases in both radiation interception and radiation use efficiency (RUE). Decreased interception was due to effects of N supply on reducing canopy leaf area, whereas the reduced RUE was associated with decreased SLN. Total biomass production in maize was more responsive to N supply than in sunflower. The major determinants of the differences in response of biomass accumulation to N supply found between maize and sunflower are: (i) sunflower tends to maintain SLN with increase in partitioning of N to leaves under N limitation whereas maize tends to maintain leaf area with increase in partitioning of biomass to leaves and (ii) the ability of maize to maintain N uptake following cessation of leaf production.     

Changes in oil,sugars and nitrogenous components during germination of sunflower seeds,Helianthus annuus

Since germination has been found to improve the nutritional quality of grains, sunflower seeds Helianthus annuus were germinated for up to five days, and the cotyledons were analyzed for oil, sugar, free amino acid, non-protein nitrogen, lysine, tryptophan and methionine contents. Protein was fractionated. Soaking and germination increased the non-protein nitrogen, total free amino acid, lysine and tryptophan contents. Protein content and dry weight decreased. The oil content decreased significantly after 72 hours of germination. The reducing sugars increased gradually until day five of germination.The saline soluble albumin and globulin fractions decreased while the glutelin content increased during germination. No changes were noticed in the prolamin and methionine contents.     

The effect of Cd2+ on lipid components of sunflower (Helianthus annuus L.) seeds

The effect of seven levels of Cd²⁺ viz. 0, 10, 20, 30, 40, 60 and 80 ppm (µg/g soil) supplied as cadmium chloride, on lipid components of sunflower seeds was studied in a pot experiment. The total and neutral lipids decreased while polar lipids (phospho and glycolipids) increased with the increasing levels of Cd²⁺. Oleic acid and linoleic acids were the major fatty acids in the total, polar and neutral lipid fractions. Oleic acid generally increased while linoleic acid decreased in all the lipid fractions with Cd²⁺ levels. The neutral lipid fraction had higher levels of palmitic, palmitoleic, stearic and oleic acid as compared to the total and polar lipid fractions. The plant dry weight and seed yield decreased whereas cadmium concentration in seeds increased consistently with increasing Cd²⁺ levels.     

向日葵对盐逆境伤害的生理反应及耐盐性研究

栽植于蛭石的向日葵用0．3％，0．6％，0．9％，1．2％NaCl水溶液胁迫处理，20d,40d时测定生理指标。结果表明：盐逆境对向日葵生长有明显伤害，对叶面积的影响大于对株高的影响；膜透性极显著增加，并随处理时间延长呈上升趋势；脯氨酸含量呈初期上升后期下降趋势；光合速率下降原因与盐浓度有关，低盐度胁迫伤害主要是气孔因素造成的，高盐度胁迫伤害则主要来自非气孔因素。     

Maize kernel growth and kernel water relations as affected by nitrogen supply

Improving maize (Zea mays L.) growing conditions near flowering by applying nitrogen (N) could affect both kernel number per unit area (KN) and potential kernel weight (KW). Potential kernel weight can be estimated with maximum kernel water content (MKWC), as final kernel weight and kernel water relations are strongly associated in maize. At the crop level, the product of KN per unit area and MKWC could provide an appropriate index of potential sink capacity. The main objective of this study was to determine if the decrease in potential sink capacity (i.e. the product of MKWC and KN), under N deficit and with a late planting date, is due to MKWC or KN reductions. Additionally, we evaluated sink growth rate per unit area (i.e. the product of KN and kernel growth rate) during grain fill period as related to potential sink capacity. Three N rates under optimal and late planting dates and two hybrids were evaluated in experiments carried out at Paraná, Argentina (31°50′S; 60°31′W) during 2002–2003 and 2003–2004 growing seasons (seasons 1 and 2, respectively). Except for the late planting date during season 1, there was a significant positive response on grain yield, KN, KW, and MKWC to N supply. Experiments explored a broad range of KN, from 1645 to 5066 kernel m⁻². MKWC and KN were positively correlated for DK682. Nitrogen increased the potential sink capacity and sink growth rate only as KN increases from a particular threshold in both hybrids. The sink growth rate was largely related to potential sink capacity, as MKWC was highly correlated with KGR across all treatments. Our analytical approach, considering potential sink capacity as a product of KN and MKWC, is integrative of sink demand both for individual kernel and crop levels. This work highlights the role of early establishment of potential sink capacity on yield determination under a wide range of N conditions.     

Interactions of sunflower (Helianthus annuus) and sunflower broomrape (Orobanche cumana) as affected by sowing date,resource supply and infestation level

The holoparasitic weed Orobanche cumana (sunflower broomrape) constrains sunflower (Helianthus annuus) production in many countries. The development of efficient control strategies requires an understanding of the processes underlying the complex environment–host–parasite interrelations. Growth and development of O. cumana and sunflower were quantified under field conditions in southeastern Romania. Sunflower hybrid Florom 350 was sown at two dates, in plots infested with 0, 50, 200 and 1600 viable O. cumana seeds kg⁻¹ dry soil, under low-input (rainfed, low nitrogen supply) and high-input (irrigated, high nitrogen supply) conditions. Sunflower shoot biomass reached peak values of 760–1287 g m⁻² between the end of anthesis and physiological maturity. Seed yield varied from 221 to 446 g m⁻². Sunflower biomass and yield were affected by all experimental factors. Seed yield responded positively to delaying sowing from early April to late May as well as to irrigation and fertilisation, and negatively to O. cumana infestation. Yield reductions, which were a product of reduced seed number and size, amounted to 13%, 25% and 37% at parasite seed densities of 50, 200 and 1600 viable seeds kg⁻¹ soil, respectively. Maximum O. cumana attachment numbers, recorded in late-sown high-input crops in 2004, ranged from 11 m⁻² in plots with 50 parasite seeds kg⁻¹ soil to 188 m⁻² with 1600 seeds kg⁻¹ soil. Parasite attachment number was a function of crop sowing date, water and nutrient supply, seedbank density, and sunflower biomass and root length density, via mechanisms of parasite seed stimulation, host carrying capacity and intraspecific competition. Delayed sowing and improved water and nitrogen supply were associated with increases in parasite number that neutralised yield-boosting effects of irrigation and fertilisation at the highest infestation level. Sunflower shoot biomass was significantly reduced by O. cumana infection, with reductions affecting organs in the order head > stem > leaves. Most of the discrepancy between infected and non-infected plants was accounted for by O. cumana biomass. Parasites mainly acted as an extra sink for assimilates during sunflower generative growth and impaired host photosynthesis to a much lesser degree. Results suggest that similar mechanisms govern infection level and host–parasite biomass partitioning across different Orobanche–host systems.     

Physical behavior of purified and crude wax obtained from Sunflower (Helianthus annuus) seed oil refineries and seed hulls

The sunflower seed waxes obtained from two sources (i) seed hull as astandard and (ii) crude wax from oil refineries were studied for theircrystallization, melting characteristics and morphology of crystals. Theresults of differential scanning calorimetry of wax obtained from seed hullsshowed the melting temperature range of 13.18 ^°C with the onsetat 62.32 ^°C, for purified wax, compared to the melting range of24.73 ^°C with the onset at 42.3 ^°C, for crude wax. Theenthalpy of fusion for both waxes were 57.55 mcal/mg and 7.63 mcal/mg,respectively. The DSC melt crystallization temperature range was15.79 ^°C with the onset of 64.58 ^°C for purified wax andtemperature range of 31.45 ^°C with an onset of 57.76 ^°C forcrude wax. A similar pattern was observed of wax obtained from thecrude wax of oil refineries. The enthalpy of crystallization was –64.27mcal/mg and –7.67 mcal/mg, respectively. The purified wax obtained fromthe two sources (i) and (ii) were comparable with completion temperaturesof 75.5 ^°C and 75.1 ^°C, respectively. The effect of inhibitor(lecithin) on crystallization of purified wax under light microscope andsurface structure by scanning electron microscope were observed. Lecithinat 0.2% inhibited the crystallization but nucleation was unaltered. Thewax crystal was inhibited to around 60% of the original size with 0.2%lecithin. It is concluded that the sunflower waxes studied were notcomparable in their crystal properties of crude and purified states.Lecithin inhibited the crystallization of sunflower seed wax.     

Seed quality as affected by nitrogen during true potato seed production and moisture conditions during storage

The objective was to investigate the effects of moisture conditions in storage at 21 C (± 3) on true potato seed (TPS) germination and seedling vigor. The influence of supplemental nitrogen (N) during seed production on these effects was also studied. One set of TPS was stored exposed to ambient humid (> 80% RH) air; the other was stored dry (sealed with silica gel). Germination tests were performed at 7, 11, and 14 months of seed storage. Seedling vigor tests were made at 14, 20, and 23 months. The rate of germination was mostly affected by the moisture conditions during storage. Seed stored dry germinated faster than TPS stored in humid ambient air. The rate of germination increased with time in storage and the percentage of germination was always high (≥ 95%) in dry seed produced with high N. Seedling vigor was mostly affected by N treatments during seed production. High-N seed had a much higher rate and percentage of emergence and seedling dry-weight levels than low-N seed, particularly when stored dry. Seedling vigor criteria decreased with time in storage in low-N seed; in high-N seed, the rate of emergence increased and the percentage of emergence was always high (≥ 95%). In conclusion, the TPS should be produced with high N and stored dry for sowing under unfavorable conditions.     

Millet forage yield and silage quality as affected by water and nitrogen application at different sowing dates

This experiment was conducted to evaluate the effects of two irrigation regimes (control and water stress) and two nitrogen (N) levels (0 and 112.5 kg/ha) on forage yield and silage quality in millet. Bastan (Setaria italica (L.) P. Beauv) and Pishahang (Panicum miliaceum) were sown at two different dates during 2015 and 2016. Both cultivars exhibited reduced dry-matter (DM) yields (45% and 51% in Bastan and Pishahang respectively) due to drought stress. Proline and phenolic contents increased as a result of drought and were significantly and negatively correlated with DM yield and digestibility. Moreover, Pishahang had a reduced acid detergent fibre (ADF) content but improved leaf/stem ratio, digestible dry matter (DDM), relative feed value (RFV), net energy for lactation (NE_L), digestibility and silage quality as a result of drought stress, while no significant effects on these traits were observed in Bastan. Silage quality was greatly cultivar-dependent. Both cultivars had higher levels of DDM, RFV and NE_L at early sowing dates. Nitrogen supply had greater positive effects on increasing ash, crude protein (CP) content and DM yield under normal irrigation than under water-stress conditions. In summary, given the importance of the energy received per unit of forage from an animal husbandry viewpoint and the significance of DM yield per unit area from an agricultural viewpoint, the obtained results might help farmers in choosing not only the best sowing dates but also proper irrigation and N management practices to achieve their quantitative and qualitative objectives in forage production.     

Rice growth and yield as affected by the whorl maggot Hydrellia philippina Ferino (Diptera: Ephydridae)

Grain yields of rice cultivars IR36 and IR40 artificially infested with Hydrellia philippina flies were compared with those of non-infested plants in two screenhouse and four field tests. Infestation rates as high as 800 flies per 49 plants resulted in 82% of the leaves damaged but did not reduce grain yields of either IR36 or IR40. Larval feeding decreased plant height and increased number of panicle-bearing tillers of IR36. Maturity of damaged plants was delayed 7–10 days.     

追肥结束期对烤烟生长发育及产质量的影响

以K326为材料，在南昌进行了3个追肥结束期对烤烟生长发育和产质量影响的研究。试验结果表明，追肥结束期早(栽后25d)有利于提高烟株的株高、总叶数、有效叶数、单株叶面积及上部10叶的叶面积和产量；追肥结束期中(栽后35d)有利于提高上等烟比例、均价和产值；追肥结束期晚(栽后45d)有利于提高平均单叶重及上中等烟比例。认为烤烟追肥结束期以栽后25～35d为宜。     

锰对大豆氮代谢相关指标及产量品质的影响

以大豆品种垦农4号为材料,在大田小区试验的条件下,研究EDTA-Mn浸种和在初花期（R1期）叶面喷施对大豆叶片可溶性蛋白、硝态氮、游离氨基酸含量、硝酸还原酶活性及产量品质的影响。结果表明,无论在浸种处理（A）还是叶面喷施处理（B）中,中浓度锰(即A3 1.54g/L和B3 20g/L)处理对大豆叶片可溶性蛋白、硝态氮、游离氨基酸含量及硝酸还原酶活性均有一定的促进作用,但随着生育期的推进,浸种处理对各指标影响效果逐渐减弱。同时,中浓度的锰处理有利于大豆单株粒数、荚数和单株产量的提高,从而达到大豆增产的目的,且能够使大豆的蛋脂总量明显提高。高浓度的锰(即A4 15.4g/L或B4 60g/L)处理则对上述指标起抑制作用。     

Herbage yield,essential oil content and composition of three oregano (Origanum vulgare L.) populations as affected by soil moisture regimes and nitrogen supply

To compare the response of oregano (Origanum vulgare L.) populations to soil moisture regimes and nitrogen fertilization, a greenhouse experiment with three populations of oregano cultivated in Germany (O. vulgare var. creticum, O. vulgare ssp. hirtum, O. vulgare var. samothrake) was conducted during 2006–2007 at the research station Rauischholzhausen of Justus Liebig University in Germany. A completely randomized experimental design with three soil moisture regimes (optimal, consistent water deficiency and water deficiency from the beginning of flowering) and two nitrogen fertilization levels with six replications was realized. Dry matter production of population O. vulgare var. samothrake was stable for two experiment years, whereas those of the populations O. vulgare var. creticum and O. vulgare ssp. hirtum were higher in 2007 than in 2006. Among tested populations O. vulgare var. samothrake showed the highest essential oil content in both experiment years. Consistent water deficiency caused reduction of dry matter, but not essential oil content. Water deficiency in flowering stage reduced also dry matter production, but increased essential oil content, resulting in the highest essential oil yield in 2006 and a comparable essential oil yield as control in 2007. Higher nitrogen levels caused an increase in dry matter production of oregano for both experiment years and a decrease in essential oil content in 2007, which can be explained in terms of dilution effect. Totally, 42 compounds were identified in essential oils of three populations by means of GC–MS. Carvacrol was the dominant compound (70.0–77.4%) for all essential oil samples, followed by γ-terpinene (8.1–9.5%) and p-cymene (4.5–5.3%). The composition of essential oil of oregano populations was independent of cultivation conditions. In conclusion, the population of O. vulgare var. samothrake showed a stable dry matter yield with higher essential oil content than the populations of O. vulgare var. creticum and O. vulgare ssp. hirtum. Water deficiency after beginning of blooming (folded flowers) can induce an increase in essential oil content and thus result in higher quality of oregano herbage and higher water use efficiency of oregano plants.     

Yield performance and grain lipid composition of standard and oleic sunflower as affected by water supply

Sunflower has potential in Mediterranean farming systems because of the modest auxiliary input requirement, appreciable productivity and quality of raw material. These aspects are affected by the interactions among genetic, environmental and agronomic factors, which have not been fully explored. Therefore, the effects of four water regimes as proportion of crop evapotranspiration (0%, 33%, 67%, 100%) on grain yield and its components, oil yield and grain lipid constituents, i.e. fatty acids (FAs), unsaponifiable matter (UM), phytosterol (Phy), policosanol (PC) and tocopherol (Toc) fractions of a standard and an oleic sunflower hybrids were assessed in a 2-year field experiment. The relationships between crop productive traits and oil quality features were also analysed.     

氮素用量对油葵氮磷钾养分吸收积累及产量的影响

为研究氮素对油葵植株氮磷钾养分积累和产量的影响,采用田间试验方法,在宁夏中部干旱带同心地区进行了油葵肥料试验。结果表明,在供试土壤条件下,氮磷钾养分积累均呈“S”型曲线,符合Logistic方程。施氮量在6～18kg/667m2之间时,均促进油葵对氮磷钾的吸收。其中,100kg籽粒所需N、P2O5、K2O范围分别是5.68～6.19kg、4.32～4.62kg、14.82～21.20kg,三要素（N:P2O5:K2O）平均比例为1:0.76:2.93。成熟期时,氮磷钾总积累量均是N2P2K2处理最高,分别达到47.99g/株、35.45g/株、152.30g/株。当施氮量为10.53kg/667m2时,产量达最高值221.02kg/667m2,最佳经济效应施氮量为9.54kg/667m2,最佳经济效益产量为220.48kg/667m2。     

Protein quality of peas as influenced by location,nitrogen application and seed inoculation

A study was conducted to evaluate the contribution of location, N application andRhizobium seed inoculation to variations in seed protein content and amino acid (AA) composition of field peas. The magnitude of AA variations with protein level and the nature of the relationships that are involved were determined. Regression equations to predict AAs from protein were developed for the cultivar Bohatyr. The experiments were carried out at two locations in southern Manitoba in 1994. The levels of N fertilization investigated were: 56, 75, 100, 125, 150, 200, 250 and 300 kg/ha. At each level of N application, seeds planted were eitherRhizobium inoculated or not inoculated. The combination of location, fertilizer treatments and inoculation yielded 192 samples for chemical analyses. The samples were analyzed for dry matter (DM), N and AA contents. Location and N fertilization had significant (p0.001) effects on seed protein content and AA composition. Seed protein content increased with increasing levels of N application. The response of protein to fertilization was not the same in both locations as evidenced from the presence of interaction (p0.01) between location and N application. Except for methionine and cystine, percent AAs in DM increased with increasing levels of N application. The effects of N application on the concentrations of methionine and cystine were not consistent. On protein basis, the concentrations of AAs decreased with increasing levels of N application. The only exception was arginine which strongly increased in concentration. There was no effect (p0.05) of seed inoculation observed in this study. Strong positive correlations (r>0.80) between seed protein content and AA concentrations expressed as percent of DM were found for all AAs except for methionine (r=0.76) and cystine (r=0.51). When AA concentrations are expressed as g per 16 g N, 15 of the 17 AAs were negatively correlated to seed protein content. Only arginine (r=0.78) and aspartic acid (r=0.17) had positive correlations. The regression equations developed from this study could be used to predict the concentrations of AAs except methionine and cystine for the cultivar Bohatyr once the protein content is known.     

Association of growth dynamics, yield components and seed quality in long-term trials covering rapeseed cultivation history at high latitudes

Brassica oilseed yield trend has declined in Finland by over 20% during the last 15 years. Improved genetic yield potential of turnip rape (B. rapa L.) and oilseed rape (B. napus L.) can be better realised with increased understanding of yield determining processes under northernmost growing conditions. This study aimed at (1) determining the genetic improvements in seed yield, yield components, quality traits and duration of the main growth phases and (2) comparing all these traits in turnip rape and oilseed rape. This work is based on the dataset from long-term Official Variety Trials (1976–2006), covering the entire historically relevant period of rapeseed cultivation in Finland. The results indicated that number of seeds per square metre dominated production of high yields, while single seed weight was not correlated with yield. Over the years, seed yields were produced with very different combinations of seed numbers and weights, differing markedly between the two crops. While high seed numbers were required for production of superior seed yields, single seed weights were not particularly high. Environmental variation markedly affected seed yield, seed number per square metre and duration of flowering compared with its effect on single seed weight. Duration of flowering was, however, negatively associated with seed number. Even though seed weight was largely determined by genotype, no marked plant breeding improvements were identified, contrary to those in number of seeds per square metre, seed yield, oil content and oil yield. For oilseed rape the increase in seed yield (41%) was far higher than for turnip rape (19%) without being associated with a longer seed-filling phase and later ripening, but rather the contrary.     

Effect of plant density on stolon growth and development of contrasting white clover (Trifolium repens) varieties and its influence on the components of seed yield

Plants of two contrasting white clover varieties (cv. Aberystwyth S184 and Olwen) were planted in the field in spring in each of 2 years at four densities (9, 25, 49 and 100 plants m⁻²) in 1-m² plots. The effect of plant density on stolon growth and development and the components of seed yield was subsequently measured.
Stolon growth and development was influenced by plant density, variety and year. At low plant densities both white clover varieties produced longer primary stolons than at higher densities. Plant density, however, had no significant effect on the number of inflorescences at harvest. At the high stolon densities there were significantly fewer reproductive nodes per primary stolon than at the lower plant densities. Plant density did not significantly affect any other seed yield components, but the number of inflorescences at harvest, florets per inflorescence, seed set per floret and 1000-seed weight were all significantly influenced by both variety and year.
The relationship between the vegetative and reproductive growth of white clover is discussed in relation to plant density, variety and climate and the possible role of defoliation managements on inflorescence development.     

The effect of the growth regulator paclobutrazol (PP333) on the growth, development and yield of Lolium perenne grown for seed

Application at spikelet initiation of the growth retardant paclobutrazol (PP333) at a rate of 2.0 kg a.i. ha⁻¹ increased the seed yield of perennial ryegrass cv. S24 from 139 to 180 g m⁻² in 1981, and from 111 to 256 g m⁻² in 1982. Yield increases were associated with an increased production of fertile tillers in both years and with an increased number of seeds per spikelet in 1982. Other yield components were not changed. Seed yield increased with increasing PP333 application rate in both years. No significant yield difference was recorded between application at spikelet and floret initiation in 1981.
Lodging was prevented completely by the 2.0-kg rate, delayed until after anthesis by the 1.0-kg rate and began before anthesis with the 0.5-kg rate. PP333 reduced stem internode length and strengthened the base of the stem; total stem dry matter (DM) was reduced, but root DM accumulation was increased at all rooting depths. Leaf area duration was significantly increased in both years.
Vegetative regrowth after seed harvest was not significantly reduced by PP333 application, but soil residual properties were demonstrated.