Effects of source/sink manipulation on net photosynthetic rate and photosynthate partitioning during grain filling in winter wheat

Source-sink relationship, which was influenced by both genotype and environmental factors, contributed to the variation in photosynthesis and photosynthate partitioning of wheat. Source reduction by partial defoliation increased leaf net photosynthetic rate (PN), and sink reduction decreased PN of irrigated wheat. However, the change in PN varied among genotypes. Source reduction enhanced photosynthate translocation into grain in irrigated wheat. However, the enhancement was more evident in cv. Lumai 215953 than incv. Lumai 15. Sink reduction had little effect on the translocation of photosynthate into grain in cv. Lumai 15, but decreased the translocation of photosynthate into grain and increased it into stem in cv. Lumai 215953. In rainfed, non-irrigated wheat, the source or sink manipulation influenced PN only slightly. The source reduction decreased the partitioning of photosynthates into the upper parts (including grains) of plant. However, very little effects of sink reduction on the production of photosynthates occurred in rainfed wheat. This showed that grain sink size was not a factor limiting the production of photosynthates, but controlled the partitioning of photosynthates. Sink reduction decreased photosynthate translocation into grains, and increased it into upper parts of rainfed wheat plant. This revised version was published online in July 2006 with corrections to the Cover Date.     

Rice cultivar difference in seedling establishment in flooded soil

Seedling establishment of direct sown rice plants is less successful in flooded soil than in drained soil. This study was conducted to clarify the difference in morphogenesis of rice seeds sown in flooded and drained soils and to identify the morphological characteristics responsible for successful establishment of cultivars in flooded soil. Rice cultivars ASD1 and IR41996–50–2–1–3, superior in seedling establishment in flooded soil, and Mahsuri and IR72, non-superior (control), were sown at a depth of 25 mm in soil flooded with 25 mm of water or in drained soil. The coleoptile and 1st leaf emerged from the soil surface simultaneously in drained soil while in flooded soil the coleoptile emerged first. The coleoptile of superior cultivars, unlike the controls, elongated more in flooded soil than in drained soil. In flooded soil, the development of mesocotyl, 1st leaf, and roots were inhibited to a greater extent in the controls, than in the superior cultivars. In sealed flasks in which gas containing 0–21% O2 was exchanged daily, the superior cultivars developed longer coleoptiles than the controls at lower O2 concentrations. These findings suggest that the reason superior cultivars grow better in flooded soil than the controls is that the coleoptile elongates faster and longer in hypoxia and is able to reach the soil surface where O2 is available.     

S-alleles are retained and expressed in a self-compatible cultivar of Petunia hybrida.

Summary We identified two S-allele-associated proteins (S-proteins) in a self-compatible cultivar of Petunia hybrida based on their segregation in F₁ hybrids between P. hybrida and its self-incompatible relative, Petunia inflata (with S₂S₂ genotype), and in selfed progeny of P. hybrida. These two S-proteins, designated S_x-protein (24 kDa) and S_o- protein (31 kDa), are pistil specific, and their expression follows a temporal and spatial pattern similar to that of S-proteins characterized in self-incompatible solanaceous species. Their amino-terminal sequences also share a high degree of similarity with those of solanaceous S-proteins. Selfing of P. hybrida yielded plants with S_oS_o, SxSo, and S_xS_x genotypes in an approximately 1:2:1 ratio, indicating that the S_x- and S_o-alleles, though expressed in the pistil, failed to elicit a self-incompatibility response. The S₂-allele of P. inflata is expressed in all the F₁ hybrids, rendering them capable of rejecting pollen bearing the S₂-allele. The S_o-allele is not functional in the F1 hybrids, because all the F₁ progeny with S₂S_o genotype are self-compatible. However, in F₁ hybrids with S₂S_x genotype, approximately half are self-incompatible and half are self-compatible, indicating that the function of the S_x-allele depends on the genetic background. These results strongly suggest that the presence of functional S-alleles alone is not sufficient for expression of a self-incompatibility phenotype, and reaffirm the multigenic nature of gametophytic self-incompatibility suggested by earlier genetic studies.     

Photosynthetic response of different pea cultivars to low and high temperature treatments

The thermo-sensitivity of two new pea (Pisum sativum L.) cultivars—Afila (mutant in the gene transforming leaves into mustaches) and Ranen (mutant for early ripening)—as compared to the control cultivar Pleven-4 to either low (4 °C, T₄) or high temperature (38 °C, T₃₈) was investigated by means of chlorophyll (Chl) fluorescence kinetics. The low temperature treatment decreased the photosynthetic activity, measured via a decline of the Chl fluorescence decrease ratios R_Fd690 and R_Fd735, and this was mainly due to a decline of the Chl fluorescence decrease parameter F_d and maximum Chl fluorescence F_m. In the new cv. Ranen the R_Fd ratios at first decreased and increased again after 24-h exposure to 4 °C, indicating its good acclimation ability to low temperature. The cold-induced changes in the photosynthetic performance of all cultivars were reversed after transferring plants back to 23 °C for 48 h. In the Chl and carotenoid (Car) contents no or little changes occurred during the T₄ treatment, except for a slight but clear increase of the ratio Chl a/b and a decrease in the ratio Chl/Car. In contrast to this, the T₃₈ treatment for 72 h decreased the R_Fd ratios more strongly than the T₄ exposure did. In fact, an irreversible injury of the photosynthetic apparatus was caused in the control pea cv. Pleven-4 by a 48-h T₃₈ exposure and for the new cv. Afila after a 72-h T₃₈ exposure. In contrast, the cv. Ranen was less and little sensitive to the T₃₈ exposure. In the heat-sensitive cvs. Pleven-4 and Afila, the decrease in R_Fd values at T₃₈ was associated with a strong decline of the Chl a+b and total Car contents. The Chl a+b decline could also be followed via an increase of the Chl fluorescence ratio F₆₉₀/F₇₃₅. Parallel to this, a strong decline of Chl a/b from ca. 3.0 (range 2.85–3.15) to ca. 1.9 (range 1.85–1.95) occurred indicating a preferential decline of the Chl a-pigment proteins but not of the Chl a/b-pigment protein LHC2. In the relatively heat-tolerant cv. Ranen, however, the ratio Chl a/b declined only partially. After the T₄ treatment the stress adaptation index Ap was higher in cv. Ranen than in controls and reached in heat-treated Ranen plants almost the starting value indicating a cold and heat stress hardening of the treated plants. The Chl fluorescence parameters and pigment contents were influenced by T₃₈ and T₄ treatments in various ways indicating that the mechanisms of low and high temperature injury of the photosynthetic apparatus are different. The new cv. Ranen exhibited a cross tolerance showing a fairly good acclimation ability to both T₄ and T₃₈, hence it is a very suitable plant for outdoor growth and for clarification of the acclimation mechanisms to unfavourable temperatures.     

不同生态品种群桃果实糖酸及其组分含量分析

以涵盖我国6个生态品种群的118份桃地方品种为试验材料,对其糖酸组分进行全面分析,以明确不同桃区果实糖酸组分分布特性,为优异糖酸种质筛选提供依据。应用斐林试剂测定果实可溶性糖含量;应用Na OH测定果实可滴定酸含量;应用高效液相色谱(HPLC)技术测定果实糖组分,离子色谱技术测定果实酸组分。结果表明:西北高旱桃区的品种,主要以可滴定酸、柠檬酸、苹果酸、总酸表现出较高的分布水平,蔗糖、总糖、糖酸比、固酸比表现出较低的分布水平;华北平原及长江流域桃区的品种,主要以糖酸比、固酸比表现出较高的分布水平,可滴定酸、柠檬酸、苹果酸、总酸表现出较低的分布水平;云贵高原桃区的品种,主要以可溶性糖、蔗糖、总糖表现出较高的分布水平,糖酸比、固酸比表现出较低的分布水平;华南亚热带桃区的品种,主要以蔗糖、总糖、糖酸比、固酸比表现出较高的分布水平,可滴定酸、柠檬酸、苹果酸表现出较低的分布水平;东北高寒桃区的品种,主要以果糖表现出较高的分布水平,糖酸比、固酸比表现出较低的分布水平。6个生态品种群的品种,果糖所占比例以长江流域桃区最高,葡萄糖以西北高旱桃区最高,山梨醇以华南亚热带桃区最高,而东北高寒桃区最低,蔗糖所占比例在不同生态区无明显差别。柠檬酸所占比例以长江流域桃区最高,而华南亚热带桃区最低,奎宁酸所占比例以华南亚热带桃区最高,琥珀酸、苹果酸所占比例在不同生态品种群间无明显差异。     

蕾后期和花前期切花菊品种'神马'不同部位叶片光合作用和叶绿素荧光特性的比较

对蕾后期和花前期切花菊(Chrysanthemum morifolium Ramat.)品种'神马'('Jinba')不同部位叶片光合作用参数日变化、叶绿素荧光参数、光响应曲线及参数进行了研究.结果表明:蕾后期和花前期品种'神马'叶片蒸腾速率(Tr)、气孔导度(Gs)和净光合速率(Pn)的日变化均为单峰曲线,峰值出现在10:00或12:00;胞间CO2浓度(Ci)的日变化则先降低后升高,谷值出现在12:00.蕾后期和花前期品种'神马'叶片Tr、Ci和Gs值的平均值总体上随叶片位置降低而逐渐升高;蕾后期不同部位叶片Pn值的平均值差异较小,花前期叶片Pn值的平均值则随叶片位置降低而逐渐降低.随着叶片位置降低,蕾后期和花前期品种'神马'叶片的初始荧光(Fo)、最大荧光(Fm)、可变荧光(Fv)、表观量子效率(AQE)和最大净光合速率(Pmax)以及蕾后期的暗呼吸速率(Rd)均逐渐降低,而花前期的Rd值以及蕾后期和花前期的光补偿点(LCP)均逐渐升高.随着光合有效辐射(PAR)升高,蕾后期不同部位叶片以及花前期中部叶和下部叶的Pn值呈先急剧升高后趋于平稳的变化趋势,而花前期上部叶的Pn值则呈先急剧升高后逐渐下降的变化趋势.研究结果显示:在切花菊设施栽培过程中适当补充光照可提高切花菊品质.     

Growth and accumulation of N, K+, Ca2+ and Mg2+ in barley exposed to various nutrient regimes and root/shoot temperatures

Six cultivars of spring barley ( Hordeum vulgare L. cvs Salve, Nümberg II, Bomi, Risø 1508, Mona and Sv 73 608) were grown in water culture for three weeks with various combinations of mineral supply and differential roots/shoot temperatures during the growth period. Most important for growth and accumulation of N, K⁺, Ca²⁺ and Mg²⁺ was the mineral supply, followed by the root temperature and the choice of cultivar. Treatments with low mineral supply or low root temperature induced a uniform reduction in growth and accumulation of the ions studied. The effects of low mineral supply and low root temperature on growth and N accumulation was additive, which indicates that these factors exert their influence independently of each other.
Roots grown at 10°C were smaller and Rb⁺(⁸⁶Rb) influx was higher than in roots grown at 20°C. It is suggested that the control of Rb⁺(⁸⁶Rb) influx is affected by the root temperature and the age of the plants. The higher ⁸⁶Rb⁺ (⁸⁶Rb) influx into the low temperature roots could not compensate for the smaller root size. However, the lower total mineral accumulation made up for the needs of the smaller plants and cannot explain the reduction in growth.     

Influence of nitrogen supply and sink strength on changes in leaf nitrogen compounds during senescence in two wheat cultivars

Changes in various nitrogen compounds during senescence of the fourth leaf were studied in two cultivars of spring wheat (Triticum aestivum L.). One of the cultivars (Yecora) was supplied with two N levels; the other (Tauro) was grown with the high N level and pruned above the fourth leaf, whereas the control was left intact. In both cultivars grown with high N supply, net nitrogen export from the fourth leaf did not occur until 35 days after sowing (DAS). Loss of leaf soluble proteins started earlier than that of chlorophylis, and coincided initially with an increase in insoluble protein. In N deficient plants the level of total N, soluble protein, and the activity of nitrate reductase (NRA. EC 1.6.6.1) started to decrease about 5 days earlier, and along with chlorophyll, continued to decrease at a faster rate, than in high N plants. Also, with low N supply, the large subunit (LSU, 58 kDa) of ribulose-1.5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) decreased in greater proportion than other soluble proteins, while with high N supply the decrease in Rubisco LSU was similar to that of other soluble proteins. Nitrogen deficiency caused a greater decrease in soluble proteins than in insoluble proteins, and NRA relative to soluble proteins. The faster senescing Tauro cultivar had lower levels of most parameters, especially NRA, soluble protein and, after 35 DAS. Rubisco LSU as a proportion of soluble protein. The decrease in sink strength due to shoot pruning did generally not affect the level of the various nitrogenous compounds until 35 DAS; thereafter the levels of most parameters, especially soluble protein, Rubisco LSU and, at late stages of senescence, insoluble protein, were higher in pruned than in control shoots. Thus, shoot pruning slows down senescence. The 56- and 78-kDa polypeptides increased, rather than decreased, with leaf age; the level of these two polypeptides showed a negative relationship with Rubisco LSU (r = -0.933 and r = -0.758, respectively).     

Transgenic rice plants: Characterization of two generations of seed progeny

Transgenic rice plants have been regenerated from kanamycin-resistant callus of Oryza sativa (cv. Taipei 309) derived from protoplasts electroporated with pCaMVNEO carrying the neomycin phosphotransferase II ( nptII ) gene. Of 6 randomly selected plants, all contained the nptll gene, but only 2 plants expressed NPTII activity. The transgenic plants were significantly shorter, produced fewer tillers, took longer to flower and had reduced fertility compared to non-transformed protoplastderived plants. Fifty-six seeds collected from one transgenic plant expressing NPTII activity germinated on medium containing kanamycin sulphate to give 16 green, first seed generation (R₁) plants. The latter could be divided into 3 groups: (i) Plants which set seed, had normal floret morphology and produced a total of 76 seeds; (ii) Plants which flowered, but which failed to set seed; (iii) Plants which failed to flower, were shorter and had significantly fewer tillers than plants of groups (i) and (ii). The nptII gene was present in all transgenic R₁ plants, but only 8 plants expressed the gene. Phenotypic characteristics, observed in transgenic R₁ plants were also seen in the transforned R₂ plants. These included reduced stature, a longer vegetative phase and reduced fertility compared to non-transformed plants.     

加工番茄丰产品种模式化选择的研究

以20个制酱专用型番茄品种（系）为试材,对产量及其构成因素、生育期性状、形态性状进行了典型相关分析;针对新疆自治区的生态条件、栽培技术和品种资源现状,提出了制酱专用型番茄丰产品种的模式;并对丰产品种的生育期因子和形态性状进行了优化,以期为加工番茄的品种选择提供理论依据．