Effect of Moisture Supply, Root Temperature, and Growth Regulators on Photosynthesis of Isolated Rooted Leaves of Sweet Potato (Ipomoea batatas)

Isolated rooted sweet potato leaves were used to study the effectof carbohydrate use and storage on photosynthesis. Tuberingof the roots was controlled (1) by varying the moisture aroundthe roots, (2) by varying the root temperature, or (3) by treatingthe leaves with growth regulators. When tubering was greatestthe total dry matter formed per unit area of leaf was also greatest.Benzyl adenine applied to the lamina increased the proportionof total dry matter in the tubers. The experiments show that increasing tuber growth increasesnet assimilation rate, supporting the view that rate of photosynthesisdepends on the capacity of sinks to accept photosynthate.     

不同生态环境下水稻基因型产量形成与源库特性的比较研究

以日本和IRRI的9个水稻品种为材料,分别以武香粳9号和两优培九为对照,在江苏南京和云南丽江研究了不同水稻基因型干物质积累与源库形成特征及其在不同生态环境下的差异.结果表明,生态环境对水稻产量和干物质积累量影响显著.高产水稻品种积累了高额干物质量,且干物质生产优势在中后期.高产品种的总颖花量、LAI及群体生长速率(CGR)都较高.稻谷产量随干物质积累总量的增加而提高,与齐穗后干物质积累量、总颖花量和LAI呈极显著正相关,与粒叶比呈显著正相关.与云南丽江点相比,群体LAI、单位面积颖花量和抽穗后干物质积累量少及生长速率(CGR)低是南京点稻谷产量低的关键因素.     

Effects of sowing time and plant age on critical nitrogen concentrations in canola (Brassica napus L.)

Critical concentrations of NO₃-N in fresh petiole tissue and total N in the dried lamina were determined for the youngest mature leaf (YML) of field-grown canola. For dry matter yield of canola sown on 4 May, critical NO₃-N concentration in the YML petiole at the rosette stage (RS) was 1.46 mg/g fresh wt. At the flower-buds-visible stage (BV) it was 0.45 mg/g fresh wt. For seed yield the values were 1.72 and 0.53 mg/g fresh wt. Critical total N concentration in the YML lamina for dry matter yield were 69 mg/g dry wt. at RS and 57 at BV. For seed yield they were 71 and 59 mg/g dry wt. Critical NO₃-N concentrations in the YML petiole of canola sown on 30 May were reduced by 50%; critical total-N concentrations in the YML lamina were not reduced to the same extent. Despite the reductions in critical N concentrations in the YML, critical N fertilizer rates for vegetative growth and seed yield were unaffected by sowing date or plant growth stage.     

西北半干旱区深旋松耕作对马铃薯水分利用和产量的影响

探明深旋松耕作技术(VRT)对西北黄土高原半干旱区马铃薯阶段性耗水、个体和群体生长状况、产量、水分利用效率和经济收益的影响,可为寻求抗旱增产、资源高效利用的耕作方法提供依据.本研究采用随机区组设计,于2016和2017年设置旋耕15 cm (TT)、深松40 cm (DLT)、深旋松耕40 cm (VRT) 3种耕作方式,测定马铃薯不同生育时期0～200 cm土层土壤贮水量、叶片SPAD值、叶面积指数、植株干物质量和产量等指标,计算阶段耗水量、水分利用效率(WUE)、商品率、商品产量、纯收益和新增收益等指标,探究深旋松耕作对马铃薯生产效率和经济效益的影响.结果表明: 与TT和DLT相比,VRT能显著促进马铃薯在盛花期和块茎膨大期的耗水,2016和2017年分别较DLT、TT增加了46.7、35.7和27.2、47.3 mm.由于VRT促进马铃薯耗水,叶片SPAD值、干物质量和叶面积指数均显著提高,证明它能促进马铃薯个体和群体发育.基于较高的个体和群体生长量,VRT的马铃薯块茎产量显著提高,分别在2016和2017年较DLT和TT增加了156.8%、47.8%和24.8%、41.0%,WUE相应地提高了92.3%、19.2%和18.9%、26.6%.深旋松耕作使马铃薯商品薯产量显著增加,纯收益和新增纯收益显著提高,在2016和2017年分别达到 12631.9、11019.1和29498.3、18245.5元·hm^-2.深旋松耕作促进马铃薯花期和块茎膨大期耗水,使马铃薯叶片SPAD值、干物质量和叶面积指数显著提高,导致块茎产量和水分利用效率明显升高,并提高了商品薯产量和纯收益,是适宜于西北黄土高原半干旱区马铃薯种植的耕作技术.     

Assimilate Conversion in Potato Tubers in Relation to Starch Deposition and Cell Growth

The activity of enzymes involved in the conversion of sucrose to starch together with the distribution of ¹⁴C-labelled photosynthate and ⁴C-sucrose was studied in potato tubers showing a range of growth rates and growth patterns. Within a particular tuber the uptake of ¹⁴C from labelled photosynthate and the conversion to ethanol-insoluble ¹⁴C was greatest in the apical tissue where both the rate of production of new storage cells and starch synthesis were likely to be greatest. Uptake and conversion of ¹⁴C was lowest in the older tissue of the tuber base. Pre-treatment of tubers with gibberellic acid reduced the total input of ¹⁴C from labelled photosynthate, reversed the gradient in ¹⁴C uptake between apical and basal tuber tissue, increased the amount of ¹⁴C per g fresh weight in the basal tissue and decreased the conversion of labelled sugars to starch. For tubers with different growth rates both the total uptake of ¹⁴C from labelled photosynthate and the ratio ethanol-insoluble ¹⁴C/ethanol-soluble ¹⁴C appeared to be correlated with growth rate. In contrast when tubers were fed directly with ¹⁴C-sucrose via the tuber surface, total uptake was independent of growth rate but the correlation between growth rate and the ratio ethanol-insoluble ¹⁴C/ethanol-soluble ¹⁴C persisted. Within a particular tuber there was a decreasing gradient in sucrose synthetase activity between youngest tissue of the tuber apex and the older tissue at the tuber base but there was no clear correlation between mean enzyme activity and tuber growth rate. ADPG-pyrophosphorylase and the ratio ADPG-pyrophosphorylase/starch phosphorylase showed some correlation with tuber growth rate. Starch synthase, starch phosphorylase and UDPG-pyro-phosphorylase activities per g fresh weight of tuber tissue appeared to be relatively constant. The results suggest that the transport of sugar from the phloem sieve tubes to the tuber storage parenchyma cells, in particular the phloem unloading step, and the conversion of sugar into starch are subject to separate regulation in the potato tuber.     

Effects of growth regulators, CCC and B9, on some potato varieties

The effects of CCC and B 9 on the growth habit of potato differed between varieties. CCC diminished stem lengths and dry weight more than Bo because CCC was applied early when shoots emerged from the soil, but B 9 was applied about 3 weeks later when several leaves had formed. In some varieties lateral stem growth was increased by treatment and in others decreased. There was an inverse relation between main stem and lateral stem growth so that varieties with vigorous main stem growth had poor lateral growth and vice-versa. Treatment with the growth-regulators diminished leaf dry weight of main stem leaves less than leaf area, but the degree of magnitudes of the changes depended on the variety. Both regulators lessened net assimilation rate. Net assimilation rate and dry matter per unit area of leaf were inversely related, possibly because accumulation of substances in leaves decreases photosynthesis. Stolon dry weight was positively correlated with main stem leaf area. There was a direct relation between stem length and tuber dry weight, suggesting that tuber initiation occurs at different stem lengths in different varieties. Tubering was earliest in Epicure and latest in King Edward. Epicure had the greatest tuber weight and smallest stem length.     

Pithiness and Growth of Radish Tubers as Affected by Irradiance and Plant Density

Pithiness in radish tubers (Raphanus sativus L.) is a syndromewhere xylem parenchyma cells die and are filled with air. Featuresassociated with rapid tuber growth such as large cells, greatdistances between strands of vascular tissue and rupture ofxylem vessels have been suggested to induce pithiness. The objectiveof this study was to analyse the extent to which pithiness inradish was related to tuber growth. Growth rates were variedby altering irradiance and plant density. In addition, the relationshipbetween pithiness and tuber growth (length, diameter, freshmass) was investigated in batches of plants grown under identicalconditions. The growth rates of shoot and tuber strongly increased withincreasing inter-plant distance and irradiance. Our resultssuggest a ‘true’ effect of assimilate supply ondry matter partitioning, as not only the ratio between shootand root dry mass, but also the slope of this relationship decreasedwith increasing irradiance and inter-plant distance. Withina treatment the ratio between tuber growth and shoot growthremained constant with plant age. Increase in length of thetuber did not appear to be an important factor in inducing pithiness.Within a batch of plants, a positive correlation between tuberdiameter and pithiness was observed only for tubers smallerthan 14 mm. An increase in both irradiance and inter-plant distanceincreased tuber size (diameter, mass) and pithiness, but theeffects on pithiness could not be ascribed only to differenttuber sizes. Pithiness strongly increased with plant age andit was concluded that pithiness occurred, to a great extent,according to genetic programming. The data showed that for treatmentswhich affect tuber growth, conclusions about their effects onpithiness depend on whether comparisons were made at the sametuber size or the same time, explaining apparent contradictionsin the literature. Raphanus sativus L.; radish; pithiness; genetic programming; cell death; light; plant density; growth rate; dry matter partitioning; shoot; tuber     

Influence of Vesicular-Arbuscular Mycorrhizal Fungi on the Response of Potato to Phosphorus Deficiency

Morphological and biochemical interactions between a vesicular-arbuscular mycorrhizal (VAM) fungus (Glomus fasciculatum [Thaxt. sensu Gerdemann] Gerdemann and Trappe) and potato (Solanum tuberosum L.) plants during the development of P deficiency were characterized. Nonmycorrhizal (NM) plants grown for 63 d with low abiotic P supply (0.5 mM) produced 34, 52, and 73% less root, shoot, and tuber dry matter, respectively, than plants grown with high P (2.5 mM). The total leaf area and the leaf area:plant dry weight ratio of low-P plants were substantially lower than those of high-P plants. Moreover, a lower shoot:root dry weight ratio and tuber:plant dry weight ratio in low-P plants than in high-P plants characterized a major effect of P deficiency stress on dry matter partitioning. In addition to a slower rate of growth, low-P plants accumulated nonreducing sugars and nitrate. Furthermore, root respiration and leaf nitrate reductase activity were lower in low-P plants than in high-P plants. Low abiotic P supply also induced physiological changes that contributed to the greater efficiency of P acquisition by low-P plants than by high-P plants. For example, allocation of dry matter and P to root growth was less restricted by P deficiency stress than to shoot and tuber growth. Also, the specific activities of root acid phosphatases and vanadate-sensitive microsomal ATPases were enhanced in P-deficient plants. The establishment of a VAM symbiosis by low-P plants was essential for efficient P acquisition, and a greater root infection level for P-stressed plants indicated increased compatibility to the VAM fungus. By 63 d after planting, low-P VAM plants had recovered 42% more of the available soil P than low-P NM plants. However, the VAM fungus only partially alleviated P deficiency stress and did not completely compensate for inadequate abiotic P supply. Although the specific activities of acid phosphatases and microsomal ATPases were only marginally influenced by VAM infection, VAM roots characteristically had a higher protein concentration and, consequently, enhanced microsomal ATPase and acid phosphatase activities on a fresh weight basis compared with NM roots. Morphological and ultrastructural details of VAM plants are discussed in relation to the influence of the VAM symbiosis on P nutrition of potato.     

Changes in antioxidant potential and sink-organ dry matter with pigment accumulation induced by hexaconazole in Plectranthus forskholii Briq

An investigation was conducted in Plectranthus forskholii by giving it different concentrations (10, 15, 20, 25, and 30 mg L(-1)) of hexaconazole, a fungicide cum plant-growth regulator, in order to find out its effects on growth, pigment composition, and antioxidant potential. The treatments were given as soil drenching on different growth stages. All the concentrations of hexaconazole used significantly decreased the stem length and leaf area, whereas side branches, fresh and dry matter content, photosynthetic pigments, and antioxidant potential were increased. The number of tubers, length and girth of tubers, fresh and dry weight of tubers and tuber pigments were found to be the highest at a 25 mg L(-1) concentration of hexaconazole. Hexaconazole application at 25 mg L(-1) concentration was found to be more effective than 10, 15, 20, 25, and 30 mg L(-1) in promoting fresh and dry weight of root tuber over 165 days after planting. The pigments like chlorophyll, carotenoid; anthocyanins, xanthophylls and antioxidants such as ascorbic acid, reduced glutathione and total phenol were significantly increased under hexaconazole treatment when compared to untreated control plants.     

Seasonal Evolution of the Quality of Fresh Glasshouse Tomatoes under Mediterranean Conditions, as Affected by Air Vapour Pressure Deficit and Plant Fruit Load

Changes in yield and quality of fresh tomatoes in response toair vapour pressure deficit (VPD) and plant fruit load werestudied under Mediterranean summer conditions. Plants thinnedto three or six fruits per truss were grown in two compartments,one at a VPD below 1.5 kPa, the other without VPD control. Theseasonal trend in fruit yield and quality was assessed fromApril to September by weekly measurement of number, fresh weightand dry matter content of harvested fruits, together with theoccurrence of blossom-end-rot (BER) and cracking. On two occasions,in July and September, sugar and acid content was measured atthree ripening stages. The seasonal decrease in fresh yieldwas attenuated at low VPD, because of higher individual fruitfresh weight, especially at low fruit load. Low VPD decreasedoccurrence of BER but like low fruit load, it increased fruitcracking. Fruit dry matter content was lower at low VPD, butwas unaffected by fruit load. Sugar content and the ratio ofsugars:acids was increased at high VPD and low fruit load, withinteractive effects depending on season and ripening stage.The influence of VPD on acid content differed with fruit loadand also changed during ripening and between seasons. Resultsshowed that water was the main limiting factor for growth offruits picked in July; at this time, reducing fruit load topromote mean fruit size had negative effects on BER and cracking.Reducing VPD reduced BER but had a negative effect on crackingand diluted both the dry matter and sugar content. For fruitsharvested later in summer, these negative effects were attenuatedbecause fruit growth was also carbon limited. Copyright 2000Annals of Botany Company Lycopersicon esculentum Mill., tomato, water and carbon stress, yield, quality, dry matter, sugar, acid, BER, volatile composition     

滴灌频率和灌水量对榆林沙土马铃薯产量、品质和水分利用效率的影响

针对陕北榆林沙土马铃薯农田灌溉不合理的问题,采用滴灌水肥一体化技术,设置4 d(D₁)、8 d(D₂)和10 d(D₃)3个滴灌频率及60%ET_c(W₁,ET_c为作物需水量)、80%ET_c(W₂)和100%ET_c(W₃) 3个灌水量水平,共9个处理,在生育期内对马铃薯生长、产量和品质等指标进行观测,分析马铃薯各指标对不同灌水处理的响应规律.结果表明: 同一滴灌频率下,W₃处理的株高、叶面积指数、干物质、产量和经济效益高于W₁和W₂处理;W₁处理的灌溉水利用效率(IWUE)最高,而水分利用效率受灌水量的影响不显著;W₃处理下产量达43442 kg·hm^-2,比W₁和W₂处理分别高23.3%和11.6%;W₃处理下纯收益达23492元·hm^-2,比W₁和W₂分别高40.4%和18.7%;W₃处理的块茎淀粉和维生素C含量最大,还原糖含量最小,分别为14.4%、18.54 mg·(100 g)^-1 FW和0.7%.相同灌水量下,低、中灌水水平下D₁处理的产量、IWUE、淀粉和维生素C含量最高,还原糖含量最低;高灌水水平下D₂处理的产量、IWUE、纯收益、淀粉和维生素C含量最高,还原糖含量最低,分别为46572 kg·hm^-2、23.04 kg·m^-3、26622元·hm^-2、14.6%、19.53 mg·(100 g)^-1 FW和0.7%.从滴灌频率和灌水量的交互作用来看,D₂W₃的产量和品质均达到最高;主成分分析法得出D₂W₃处理得分最高.因此,D₂W₃(8 d,100%ET_c)处理高产优质,且水分利用效率较高,为最佳滴灌频率和灌水量.研究结果可为陕北榆林沙土马铃薯高产高效优质生产中灌溉制度的制定提供依据.     

硫硒配施对茎瘤芥生长和营养效应的研究

以茎瘤芥品种‘涪杂1号’为材料,通过盆栽实验探讨不同浓度的硫(S)、硒(Se)配施处理对茎瘤芥干物质积累、矿质元素吸收及膨大茎营养品质的影响,为生产中合理施用硫、硒肥提供理论依据.结果表明:与对照(S0Se0,未施硫硒肥)相比,增施硫、硒肥处理均能显著提高茎瘤芥的根、膨大茎、叶片和单株干物质产量,并以S50Se1[S/Se=50(mg/kg)/1(mg/kg)]和S100Se1的处理效果较好,其单株干物质产量分别比对照显著增加32.3%和36.2%;不同硫、硒浓度配施处理对茎瘤芥13种矿质元素积累的影响不同,主要显著促进了茎、叶对氮、磷、钾、硫、硒的吸收积累,而对其它元素的影响不显著,其中茎、叶的硒含量以S50Se3处理最高,硫含量以S100Se1处理最高;各硫硒配施处理对膨大茎营养品质的影响不同,其中S50Se1和S50Se3处理能显著提高膨大茎有机硒、总氨基酸和粗蛋白含量,而对维生素C和可溶性糖含量无显著影响.可见,适宜的硫硒配施可以明显促进其对矿质元素的吸收,提高植株干物质积累,有效改善茎瘤芥膨大茎营养品质,且硫硒配施用量以S 50mg/kg、Se 1mg/kg为宜.     

Effects of exogenously applied growth regulators on shoot growth of inbred lines of Plantago major differing in relative growth rate: differential response to gibberellic acid and (2-chloroethyl)-trimethyl-ammonium chloride

The possibility of modulating shoot growth charaeteristics of seedlings of two inbred lines of Plantago major L., differing in relative growth rate (RGR), by exogenously applied 6-benzylaminopurine (BA), α-naphthalene acetic acid (NAA), (gibberellic acid (GA₃) and (2-chloroethyl)-trimethyl-ammonium chloride (CCC) was investigated. BA completely inhibited growth of the shoot at a concentration of 1 m M , while lower concentrations had no effect. NAA reduced growth of the shoot at 10 ü M , while 1 m M completely inhibited growth. Addition of 10 μ M GA₃ or higher stimulated shoot fresh weight up to 20% and leaf area up to 30% for the slow growing inbred line (W9), but less for the fast growing line (A4). Application of 1 m M CCC, an inhibitor of gibberellin metabolism, reduced growth of both inbred lines, but to a larger extent in the fast growing seedlings.
The lower shoot growth of W9 was associated with a lower specific leaf area (SLA) and a higher dry matter percentage of the shoot, as compared with A4. NAA reduced growth by reducing SLA and increasing leaf thickness, but the percentage dry matter of the leaves was unaffected. Stimulation of the shoot growth by GA₃ application was associated with higher SLA and lower dry matter percentage. Application of CCC had opposite effects on SLA and dry matter percentage as compared with GA₃. GA seems to be involved in the regulation of at least part of the genetic difference in RGR in Plantago major .     

Performance of some elite potato cultivars under abiotic stress at North Sinai

The current experiment was adopted during the summer 2018, fall 2018/2019 and summer 2019 respectively at the Experimental Farm of Baloza station, Desert Research Center. North Sinai Governorate, Egypt to study the effect of different doses of irradiation (0, 20, 30 and 40 Gy), three irrigation levels (100, 80 and 60% field capacity on growth, yield and its quality of some potato cultivars (Spunta, Cara, Caruso and Hermes). Treated Spunta cultivar pre planting with 20 (Gy) and irrigated with 80% field capacity was the best treatment for increasing number of aerial stem/plants, leaf area, total chlorophyll in leaves, average tuber weight, and total yield/fed. Hermes cultivar with 20 (Gy) and irrigation level of 80% was the best for increasing dry matter content in tuber in both mutagenic generations.     

Response of potato grown under non-inductive condition paclobutrazol: shoot growth, chlorophyll content, net photosynthesis, assimilate partitioning, tuber yield, quality, and dormancy

The effect of foliar and soil applied paclobutrazol on potato were examined under non-inductive condition in a greenhouse. Single stemmed plants of the cultivar BP1 were grown at 35(±2)/20(±2) °C day/night temperatures, relative humidity of 58%, and a 16 h photoperiod. Twenty-eight days after transplanting paclobutrazol was applied as a foliar spray or soil drench at rates of 0, 45.0, 67.5, and 90.0 mg active ingredient paclobutrazol per plant. Regardless of the method of application paclobutrazol increased chlorophyll a and b contents of the leaf tissue, delayed physiological maturity, and increased tuber fresh mass, dry matter content, specific gravity, dormancy period of the tubers. Paclobutrazol reduced the number of tubers per plant. A significant interaction between rates and methods of paclobutrazol application were observed with respect to plant height and tuber crude protein content. Foliar application gave a higher rate of net photosynthesis than the soil drench. Paclobutrazol significantly reduced total leaf area and increased assimilate partitioning to the tubers. The study clearly showed that paclobutrazol is effective to suppress excessive vegetative growth, favor assimilation to the tubers, increase tuber yield, improve tuber quality and extend tuber dormancy of potato grown in high temperatures and long photoperiods.     

The effect of triacontanol on micropropagation of balm, Melissa officinalis L.

 Triacontanol, a long-chain primary alcohol was found to be an effective growth regulator in the micropropagation of balm, Melissa officinalis. In both the multiplication and the rooting phase, concentrations of 2, 5, 10 and 20 μg triacontanol per liter were applied. After 4 weeks of culture, the fresh weight of shoots was measured in the multiplication phase and root formation, photosynthetic activity, chlorophyll content and the fresh and dry weights of shoots were analyzed in the root induction phase. In the multiplication phase, 5 μg/l triacontanol was found to be the optimal concentration, while in the rooting phase 2 μg/l was the most effective. Triacontanol increased the number and length of roots, and it enhanced shoot growth, fresh weight, and the chlorophyll content, but it had no effect on the dry weight and the photosynthetic activity of the plants. Results of our work demonstrate that triacontanol can be applied as an effective growth regulator in the tissue culture of balm. Received: 3 December 1997 / Revised: 24 February 1998 / Accepted: 26 February 1999     

An analysis of the effects of nutrient supply on the growth of potato crops

Fertilizer nitrogen did not delay tuber initiation by the potato variety King Edward in the field, but slowed the early growth of tubers. Later, N hastened tuber growth and the largest amounts prolonged it. Leaf and stem growth were increased by N from an early stage. Leaf area index (L) reached maxima of 2.5 to 3.0 with the largest amounts of N, and 1.0 with no nitrogen: L decreased after late July, faster with increased N, and only the largest amount prolonged the life of the haulm. N increased leaf area duration (D) by up to 125% in both years. D was 21% greater in 1964 than 1963, and net assimilation rate in August and September was larger; consequently mean yield was 50% more in 1964. Uptake of nitrogen and N % of dry matter were increased by increasing nitrogen. The N % of tuber dry weight remained constant or increased slightly from about 2 weeks after tuber formation, while N % of the leaves and stems decreased rapidly, and much N was transferred from tops to tubers. The 1964 results suggest that tuber growth depends on continued nitrogen uptake by the plant. P and K had small effects compared with those of N. K increased leaf area duration by 9% in 1963 and 3% in 1964, and yield by 11 and 8% respectively. P increased leaf area duration by 17% and yield by 9% in 1964. K had very small effects until the end of the season, when it prolonged the period of growth. P increased growth rates of all parts of the plant up to 4 weeks from emergence, and the differences in dry weight at that time persisted to maturity but did not increase.     

Size-related consumption of Scirpus maritimus tubers by greylag geese Anser anser explained by their functional response

To explain the preference of wintering greylag geese Anser anser for small Scirpus maritimus tubers (<10mm) over larger ones, our hypothesis was that the former would provide higher intake rates. This 'consumption rate hypothesis' was tested experimentally by deriving the functional responses of geese feeding on tubers of three contrasting sizes. Goose consumption rates were measured as: (i) feeding rate (tubers/min) and (ii) instantaneous intake rate (g fresh weight/min) on various tuber densities (5-200 tubers/tray). Geese had linear functional responses over the range of tuber densities offered, and tuber size affected their consumption rate. The results were then used to re-examine intake rates according to relative biomass of tubers found in the wild. In support of our hypothesis, the larger tubers allowed the lower intake rates. Foraging mechanisms that possibly control the tuber ingestion rate of geese were explored. After controlling (through chemical analyses) that nutritional components of tubers do not differ between sizes, it was concluded that geese preference is mainly due to size-related constraints (i.e. handling time) on their ingestion rates. Additional limiting factors (tuber extraction, digestion capacity) which are likely to constrain food intake of wild geese are also discussed.     

Relationship of endogenous abscisic Acid to sucrose level and seed growth rate of soybeans

It has been proposed that abscisic acid (ABA) may stimulate sucrose transport into filling seeds of legumes, potentially regulating seed growth rate. The objective of this study was to determine whether the rate of dry matter accumulation in seeds of soybeans (Glycine max L.) is correlated with the endogenous levels of ABA and sucrose in those sinks. The levels of ABA and sucrose in seed tissues were compared in nine diverse Plant Introduction lines having seed growth rates ranging from 2.5 to 10.0 milligrams dry weight per seed per day. At 14 days after anthesis (DAA), seeds of all genotypes contained less than 2 micrograms of ABA per gram fresh weight. Levels of ABA increased rapidly, however, reaching maxima at 20 to 30 DAA, depending upon tissue type and genotype. ABA accumulated first in seed coats and then in embryos, and ABA maxima were higher in seed coats (8 to 20 micrograms per gram fresh weight) than in embryos (4 to 9 micrograms per gram fresh weight. From 30 to 50 DAA, ABA levels in both tissues decreased to less than 2 micrograms per gram fresh weight. Levels of sucrose were also low early in development, less than 10 milligrams per gram fresh weight at 14 DAA. However, by 30 DAA, sucrose levels in seed coats had increased to 20 milligrams per gram fresh weight and remained fairly constant for the remainder of the filling period. In contrast, sucrose accumulated in embryos throughout the filling period, reaching levels greater than 40 milligrams per gram fresh weight by 50 DAA. Correlation analyses indicated that the level of ABA in seed coats and embryos was not directly correlated to the level of sucrose measured in those tissues or to the rate of seed dry matter accumulation during the linear filling period. Rather, the ubiquitous pattern of ABA accumulation early in development appeared to coincide with water uptake and the rapid expansion of cotyledons occurring at that time. Whole tissue sucrose levels in embryos and seed coats, as well as sucrose levels in the embryo apoplast, were generally not correlated with the rate of dry matter accumulation. Thus, it appears that, in this set of diverse soybean genotypes, seed growth rate was not limited by endogenous concentrations of ABA or sucrose in reproductive tissues.     

Effects of feeding green forage of sulla (Hedysarum coronarium L.) on lamb growth and carcass and meat quality

The nutritional effects of sulla (Hedysarum coronarium L.) forage containing condensed tannins (CT) on growth of lambs, and carcass and meat quality were investigated. Thirty-two male Comisana lambs aged 100 ± 8 days weighing 19.0 ± 2.8 kg were fed fresh forage of sulla or CT-free annual ryegrass (Lolium multiflorum Lam. subsp. Wersterwoldicum) for 49 days until slaughter; in addition, each lamb was supplied with 200 g/days of concentrate. Eight lambs per diet had been previously treated with anthelmintic drugs to remove nematode parasites. Measurements of BW and feed intake, and counts of faecal nematode eggs were made. Carcass parameters were recorded after slaughter, and tissue components of the hind leg were determined. Longissimus dorsi meat was evaluated for pH, colour, thawing and cooking losses, Warner-Bratzler shear force, chemical composition and sensory properties based on triangle tests. Relative to ryegrass-fed lambs, sulla-fed lambs had significantly greater dry matter (DM) and protein intake, a more favourable feed conversion ratio, and superior growth rate, final BW at 150 days of age, carcass weight, yield and fatness. These results were attributed to the high protein and non-structural carbohydrate content of sulla, and also to the moderate CT content of sulla (16.7 and 20.3 g/kg of DM in offered and consumed sulla forage, respectively). Anthelmintic treatment did not affect lamb growth, as the level of parasitic infection (initial and final) was low. The physical, chemical and sensory properties of the lamb meat were not influenced by diet.