鲆鲽类白化机理的研究进展

鲆鲽类体色白化，在苗种生产过程中常见。很多学者对其进行过研究，然而关于白化的机理仍然不清楚。本文就近年来国内外有关鲆鲽类白化机理的研究从营养、遗传、环境、生理等方面进行综述。     

陆地棉体细胞胚的白化与植株再生的关系

通过对棉花体细胞胚胎发育过程的观察发现，其发育的四个时期即球形期，心形期，鱼雷期和子叶期均有白化现象。成熟期的白色叶胚比绿色子叶胚在成苗培养基上生长快，且形成再生植株的频率高。     

Relationship between light,fruit and leaf mineral content with albinism incidence in strawberry (Fragaria x ananassa Duch.)

A study was conducted in strawberry to establish a relationship between shading, mineral nutrient of leaves and fruits with albinism incidence. Plants grown under shade produced albino fruits in higher proportion than those grown in open fields. Similarly, plants under shade produced smaller sized fruits and have lower fruit yield. Among cultivars, Etna had highest incidence of albinism (49.6%) and Sweet Charlie the lowest (14.4%). Dry matter content (%), concentration of five major nutrients, viz. N, P, K, Ca, Mg, S and N:Ca and K:Ca nutrient ratios did not differ significantly in the leaves of plants producing normal or albino fruits. However, in contrast, the concentration of K was notably higher (1.97 mg g⁻¹ fresh tissue weight) and that of Ca was lower (0.098 mg g⁻¹ fresh tissue weight) in albino fruits than normal ones. Consequently, the ratios of N:Ca (11.34) and K:Ca (20.08) were higher in albino fruits than normal ones. Cultivars also differed widely in respect to dry matter (%), mineral content and nutrient ratios. Thus, it appears that lower light intensity favours the development of albinism in strawberry, and it seems that calcium is not the basic cause of albinism, but increased vigour associated with overuse of N and K might be positively associated with it.     

Interactive effects of planting time and mulching on ‘Chandler’ strawberry (Fragaria × ananassa Duch.)

Studies were conducted in ‘Chandler’ strawberry with the aim to optimize planting time and mulching material under the semi-arid region of north Indian plains. Three planting times viz., mid-September, mid-October and mid-November and three mulch materials viz., black polyethylene (50 μm), clear polyethylene (50 μm) and paddy straw (10 cm thickness) were tried with three replications in a split plot design. Mid-September planting favoured plant growth, enhanced flowering (77.3 days), which resulted in production of significantly larger fruit (13.0 g) and higher yield (174.4 g/plant) with fruit having higher TSS (9.23%), acidity (1.22%) and ascorbic acid content (44.1 mg/100 g of pulp) with lesser incidence of albinism (9.6%) and botrytis rot (8.1%) than other plantings. Plants mulched with black polyethylene have significantly better growth, and they flowered (80.2 days) and fruited early (29.2 days), and produced larger fruit (12.6 g) and higher yield (172.4 g/plant), with slightly higher incidence of albinism (20.1%), but with lower incidence of botrytis rot (7.3%) than those mulched either with clear polyethylene or paddy straw. Planting time × mulching interaction has significantly influenced plant growth; flowering and fruiting; fruit yield and quality, and albinism and botrytis rot. Plants have best growth parameters like, plant height (11.2 cm), crown spread (24.1 cm) and leaf area (87.9 cm²), they took lesser days to flowering (73.7 days) and fruiting (31.3 days), produced larger fruit (13.7 g) and higher yield (191.3 g/plant) with fruit having higher TSS (9.41%), acidity (1.17%) and higher ascorbic acid content (46.4 mg/100 g pulp) with a slightly higher incidence of albinism (10.3%), but comparatively lower incidence of botrytis rot (5.2%) when planted during mid-September and mulched with black polyethylene than other plantings and mulched either with clear polyethylene or paddy straw. These studies indicated that strawberry could be planted in mid-September with black polyethylene mulch under semi-arid regions of India for early fruiting, and higher yield of better quality fruits.     

苦瓜白化苗生长发育调查分析

[目的]调查春、秋两季苦瓜白化苗生长发育情况。[方法]选取2015年早熟纯系品种ZS10-7种子1 000粒,分别在2016年春、秋两季各播种500粒,对出现的白化苗进行跟踪调查。[结果]秋季苦瓜白化苗较春季苦瓜白化苗生长发育要快一些,总体的性状尺寸相差无几。[结论]苦瓜白化苗实际存活时间不超过30 d,一旦发现有白化苗可直接拔去。     

小麦突变体返白系返白机理的研究 Ⅳ.不同播期对返白表达及某些生化反应的影响

分期播种对小麦返白系返白表达的起始时间没有影响;但与适期播种的返白系比较,早播返白发生的生育期推后,返白过程缩短;晚播返白发生的生育期提前,返白过程延长。返白过程中,叶绿素含量、可溶性蛋白、游离氨基酸总量及蛋白水解酶活性在不同播期中变化趋势一致,仅在数量及时间上表现出明显差异。并反映出温度及返白前期的植株营养基础对整个返白历程同样具有较大的影响。     

Pre-harvest foliar application of calcium and boron influences physiological disorders,fruit yield and quality of strawberry (Fragaria × ananassa Duch.)

Studies were conducted in ‘Chandler’ strawberry to determine if pre-harvest foliar application of Ca, B or their combination influences physiological disorders, fruit yield and quality or not. For this, treatments consisted of (i) five sprays of calcium as CaCl₂ (first spray was performed at the petal fall stage and later at 7 days interval), (ii) three sprays of boron as boric acid (first spray at the beginning of flowering and later at 15 day interval), (iii) combination of (i) and (ii), and (iv) plants sprayed with water served as the control. Results indicated that fruit harvested from plants, which were sprayed either with Ca or Ca + B had significantly lesser incidence of albinism (6.7 and 6.5%), and grey mould (1.3 and 1.2%) than those harvested from plants sprayed either with B alone or in control. Although, B alone could not influence the incidence of albinism and grey mould, but it reduced fruit malformation (3.4 and 3.1%) significantly. Further, Ca, B or their combination had not influenced the individual berry weight, but marketable fruit yield differed significantly. The lowest marketable fruit yield (149.3 g/plant) was recorded in plants under control, and the highest (179.2 g/plant) in plants sprayed with Ca + B. Similarly, such fruit were firmer; had lower TSS, higher acidity and ascorbic acid content at harvest than those in control. Similarly, such fruit after 5 days storage were firmer and brighter, and have significantly lower TSS (7.9 and 7.8%); higher ascorbic acid content (43.7 and 45.0 mg/100 g pulp) and acidity (1.08 and 1.07%) than those in control or those receiving B alone. Incidence of grey mould was significantly lesser in fruit, which received Ca (2.2%) or Ca + B (1.9%) than those, which received either B (8.1%) alone or those in control (8.4%). Our studies indicated that pre-harvest foliar application of Ca + B is quite useful for reducing the incidence of disorders and getting higher marketable yield in ‘Chandler’ strawberry.     

Gibberellic acid influences the production of malformed and button berries,and fruit yield and quality in strawberry (Fragaria × ananassa Duch.)

Experiments were conducted to observe the effects of foliar application of gibberellic acid on vegetative growth, flowering, fruiting and various disorders in ‘Chandler’ strawberry. GA₃ (75 ppm) was applied to the strawberry plants either during mid-November (at fruit bud differentiation stage), or mid-February (pre-flowering stage) or at both times. Fruit under control were sprayed with tap water only. Observations were recorded on vegetative attributes like crown height, crown spread, petiole length, leaf number, leaf area; flowering and fruit set, fruit size; production of albino, malformed and button berries, total yield and marketable fruit yield and quality parameters, like juice content, TSS, ascorbic acid contents, acidity etc. Results indicated that GA₃ (75 ppm) spray either during mid-November or mid-February or at both times has favourably influenced all vegetative attributes of ‘Chandler’ strawberry over control. Similarly, fruit set was increased, and production of malformed and button berries was reduced, but albinism remained unaffected. Although individual berry weight was reduced slightly, but fruit number, total as well as marketable yield was increased tremendously over control with no adverse effect on fruit quality parameters. In all, spraying GA₃ both during mid-November and mid-February was much more effective in achieving the desirable results than single application of GA₃ either during mid-November or mid-February.     

温度对小麦返白系返白基因表达的效应研究

试验结果表明，返白系返白基因表达与否取决于环境温度，而与光照变化无关。诱导近白基因表达的临界低温值大抵在旬均气温５℃左右，而诱导部位是处于低温临界内的新生叶片的生长部位。     

低温条件下小麦返白系叶片中H2O2累积的原因初探

为了研究低温处理下小麦叶色阶段性白化品种返白系与对照品种矮变1号叶片的H_2O_2含量是否存在差异,并初步分析导致差异的原因,采用DAB组织染色法检测返白系和矮变1号在4℃低温处理90 d、25℃下恢复培养10 d时叶片H_2O_2含量的动态变化,测定4℃低温处理下返白系和矮变1号中表征光合电子传递效率的荧光参数F_v/F_m和qP,并采用qRT-PCR方法分析返白系和矮变1号中几个光合电子传递体基因及质体H_2O_2清除相关基因的表达模式。结果显示,低温处理下,矮变1号叶片中H_2O_2含量变化不大,返白系叶片中H_2O_2会大量累积;低温处理下,返白系叶片的叶绿素荧光参数F_v/F_m、qP都明显低于矮变1号。同时,低温下返白系光合电子传递链中部分电子传递体亚基基因petD、petN、ndhB和ndhK,以及质体H_2O_2清除相关基因 APX4和 HO1的表达量低于矮变1号。这些结果表明,低温处理下,相较于矮变1号,返白系叶片中会累积大量的H_2O_2。返白系质体中光合电子传递受阻引起电子泄露,同时质体中清除活性氧的能力下降,可能是导致返白系叶片中积累大量H_2O_2的原因。