Quantitative studies on the relationship between plowing into soil of clubbed roots of preceding crops caused by Plasmodiophora brassicae and disease severity in succeeding crops

The effect of the plowing of clubbed roots of cracifers on the population of Plasmodiophora brassicae in soil was quantitatively studied by measuring the number of resting spores produced in the diseased plants. Though the mean number of resting spores per diseased plant increased with the increase of the disease severity, it remained almost identical for the disease severity classified into category 3 among host species and cultivars tested. Mean number of resting spores per diseased plant ranged from 9.3 to 10.9 (log) regardless of the value of the disease index. When the number of resting spores in soil was calculated based on these data and plant cultivation methods, the values were equivalent to 4.8-6.4 resting spores g^-1soil (log)where clubroot disease occurred severely. The value of the disease index of Chinese cabbage plants grown in the pots where clubbed roots of initially grown plants had been plowed into soil (plowing plot) was higher than that in the pots where no plants had been grown (control plot) and where the clubbed roots of initial plants had been removed (removal plot). Though the number of resting spores of P. brassicae in soil decreased by 14% of the inocoKum concentration immediately after the inoculation, the number of spores after the first cultivation in the removal plot was similar to that in the control plot. On the other hand, the number of resting spores in the plowing plot increased significantly compared with that in the control plot. The plowing of clubbed roots into soil resulted in the increase of the population of P. brassicae and disease severity of clubroot in subsequent cultivation in the field. The results corresponded to the values estimated based on the number of resting spores in soil in relation to each value of the disease index.     

胡萝卜肉质直根的发育形态解剖学研究

胡萝卜肉质直根的形成是由下胚轴和根的上部形成的，在肉质直根增粗过程中，没有异常结构，但在初生木质部中央有由管胞和薄壁组织细胞构成的－“混生髓”。     

临丰116旱地覆膜栽培的抗旱增产原因分析

在旱地覆膜栽培条件下，临丰116具有良好的苗型结构和产量结构，抗旱节水优势强，叶片功能期长，耐高温，抗干热风，根穗比值大，抗倒伏，不早衰，穗大，粒重，产量高。该品种是旱地覆膜栽培较理想的配套品种。同时探讨了覆膜栽培配套品种的育种目标。     

Aluminium tolerance in wheat: correlating hydroponic evaluations with field and soil performances*

The objective of this study was to correlate root length of wheat (Triticum aestivum L.) genotypes grown in Al-containing, acidic hydroponic solutions, with root weights from acid-soil experiments and field scores from Brazilian acid-field trials. A total of 43 wheat genotypes, primarily from Brazil, were evaluated by growing seedlings for 4 days in hydroponic solutions containing 0.0–4.0 mg/l Al. The root growth rate of all the genotypes was reduced with the addition of Al to the solution and the Al-sensitive and Al-tolerant wheat genotypes were clearly identified. Genotypes with intermediate Al-tolerance levels showed variable root lengths in response to Al stress. Correlations between root length or a root tolerance index (RTI) in the Al solutions versus acid-soil experiments and acid-field trials were highly significant (r = 0.71–0.85, P < 0.01). The most significant correlation was observed among seedlings grown in 1 mg/1 Al. This study presents evidence that this short duration and simple screening technique provides a highly significant correlation with previous acid-soil Al-tolerance evaluations. Furthermore, the data obtained suggest that hydroponic screening of wheat seedlings for Al tolerance may be used in breeding programmes or in screening germplasm collections.     

伐后竹蔸清理技术研究

分析了现有竹林伐后竹蔸(桩根)清理技术的缺点,即人工挖掘劳动强度较大,劈裂腐烂法其林地更新速度较慢,化学腐蚀法的剩余化学试剂会对大气环境造成一定污染等,设计了一种质量轻、体积小、移动方便、功效高,且能在地形土质复杂的稠密竹林内移动作业的竹蔸清理设备.     

丝瓜子叶原生质体培养研究

经1%纤维素酶、0.5%离析酶、3mmol/L MES 和0.25mol/L 甘露醇的CPW 酶液酶离出的丝瓜子叶原生质体,在去NH_4NO_3的KM_(8p)附加0.5mg/L 2、4-D、lmg/L BA、125mg/L 水解酪蛋白(CH)、0.15～0.20mol/L 葡萄糖和0.05mol/L 蔗糖的培养基上培养出微愈伤组织,再经MS附加多种成分的培养基培育,增殖出大量松散粒状、表面光滑的多种形态愈伤组织,并分化出根。     

红锥切根育苗试验研究

通过红锥切根、沾灰育苗试验，分析成苗率、苗高、地径、主根、须根及枝、叶等一系列苗木数量、质量性状的差异。结果表明：切根能使红锥苗木主根变短，侧根部位提高，根系发达，苗木地径和苗高明显增加，生长旺盛。但切根也在一定程度上降低了成苗率。     

冬季修剪对苹果新根细胞分裂素含量的影响研究

本试验以盆载３年生新红星／海棠为试材，应用高效液相色谱分析方法，研究了冬季修剪对苹果新根内源细胞分裂素含量的影响。新根中玉米素核苷（ＺＲ）、玉米素（Ｚ）的含量，缓放植株高于短截植株；但ＺＲ／Ｚ的比值，缓放植株低于短截植株。     

西双版纳黄瓜子叶原生质体培养

西双版纳黄瓜子叶在含1%纤维素酶、0.5%离析酶、加或不加0.3%半纤维素酶和0.3mol/L 甘露醇的CPW 酶液中游离出大量优质原生质体。浅层培养在附加0.5mg/L2.4-D 和1.0mg/L KT 等成份的KM_(8P)(-NH_4~+)培养基上,形成了微愈伤组织。转接到MS 附加多种成分的固体培养基上,愈伤组织得到增殖和生根。     

杉木连根采掘试验研究

本文通过对杉木全树采伐工艺分析和采掘试验研究。结果表明:杉木连根拔树采掘可延长应用主干28cm,造6m材每单株平均可净增产值25.78元,是一种综合利用杉木资源,提高经济效益的有效途径。