Study on stripe rust (Puccinia striiformis) effect on grain filling and seed morphology building of special winter wheat germplasm Huixianhong.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is an airborne fungal disease which always destructs leaf and leads to stagnation of grain filling, decreasing of kernel weight, thin seed and yield loss. Winter wheat Huixianhong is a special germplasm with special characteristics of tolerance or resistance against stripe rust. In order to understand the effect on Huixianhong from stripe rust, we designed two kinds of treatment, inoculation of stripe rust fungi (IH) and artificial immune by bactericide (CK) to study the dynamic of disease process, the grain filling and the thousand-kernel weight (TKW). Our results showed that the incubation period of Hongxinahui was 13.5 days. The prevalence increased from 32.9% at 15 days after jointing to 80.0% at 9 days after booting, and reached to 97.0% at the heading stage. The infection type (IT) was 7 to 9 at the beginning of anthesis. The severity, leaf withered area ratio and disease index at the 15th day after anthesis were 67.17%, 98.17% and 0.6717, respectively. The IH maximum increasing rate of leaf necrosis and chlorosis area was from heading beginning stage to anthesis beginning stage, which increased from 18.66 mm2·d-1 to 21.04 mm2·d-1. The maximum rate of grain filling was 1.25 mg·d-1 at the 18th day after anthesis, which was earlier than that of CK by 3.3 days. The IH thousand-kernel weight Loss (TKWL) was more than that of CK by 6.19%, the stage of heading and amature were 3.0 days and 4.5 days earlier than CK, respectively. The stripe rust infection seriously destructed the photosynthetic function of leaf at the earlier stage of grain filling, i.e. at the beginning of anthesis, which led to the most important biomass loss and the grain filling rate decrease. As far as stripe rust is concerned, Huixianhong is a high susceptible, easily been infected, seriously showing symptoms and most quickly epidemic type but can successfully complete grain filling in high quality. It is a very useful germplasm for creating and selecting special breeding materials against stripe rust.

Nitric oxide and hydrogen peroxide alleviate drought stress in marigold explants and promote its adventitious root development.

Drought stress is one of the most important environmental factors that regulates plant growth and development. In this study, we examined the effects of nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) on adventitious rooting in marigold (Tagetes erecta L.) under drought stress. The results showed that the promoting effect of NO or H(2)O(2) on rooting under drought stress was dose-dependent, with a maximal biological response at 10 µM NO donor sodium nitroprusside (SNP) or 600 µM H(2)O(2). Results also indicated that endogenous NO and H(2)O(2) may play crucial roles in rooting under drought conditions, and H(2)O(2) may be involved in rooting promoted by NO under drought stress. NO or H(2)O(2) treatment attenuated the destruction of mesophyll cells ultrastructure by drought stress. Similarly, NO or H(2)O(2) increased leaf chlorophyll content, chlorophyll fluorescence parameters (Fv/Fm, ΦPS II and qP), and hypocotyls soluble carbohydrate and protein content, while decreasing starch content. Results suggest that the protection of mesophyll cells ultrastructure by NO or H(2)O(2) under drought conditions improves the photosynthetic performance of leaves and alleviates the negative effects of drought on carbohydrate and nitrogen accumulation in explants, thereby adventitious rooting being promoted.

[Effects of different conservation tillage measures on winter wheat water use in Wuwei oasis irrigated area].

Field experiments were conducted in 2006-2008 to study the effects different conservation tillage measures, including conventional tillage with stubble incorporating (TS), no-tillage without stubble retention (NT), no-tillage with stubble standing (NTSS), no-tillage with stubble retention (NTS), on the soil moisture profile, soil water storage, water use efficiency (WUE), and grain yield of winter wheat in Wuwei oasis irrigated area. Comparing with conventional tillage, NTS and NTSS could significantly increase the water storage in 0-30 cm soil layer from returning green to jointing stage, and increase this storage in 30-150 cm soil layer from returning green till maturity. NTS, NTSS, and NT increased the water storage in whole soil profile (0-150 cm) by 29.55-34.69 mm, 17.32-21.79 mm, and 0.89-15.68 mm at sowing, and 37.59-38.35 mm, 5.70-22.14 mm, and 4.61-13.93 mm at harvesting, respectively. The difference in water storage became more significant with increasing soil depth. NTS, NTSS, NT and TIS increased the grain yield of winter wheat by 15.65%-16.84%, 6.98%-12.75%, 5.88%-11.74%, and 3.92%-8.16%, and the WUE by 17.15%-17.52%, 7.75%-9.65%, 8.24%-10.00%, and 4.17%-9.91%, respectively. NTS and NTSS improved the rain water use efficiency and grain yield, being the efficient conservative tillage measures to alleviate the lack of water resource in the study area.

[Effects of water supply and 3-methylphenol on soil microbial diversity and enzyme activity in wheat field intercropped with horse bean].

With pot experiment, this paper studied the effects of water supply levels (45%, 60% and 75% of soil water hold capacity) and allelochemical 3-methylphenol (300 x 10(-6) mol x kg(-1) soil) on the soil microbial diversity and enzyme activity in mono-cropped and horse bean-intercropped wheat fields during vigorous growth period. The results showed that with the decrease of water supply, the numbers of soil bacteria, fungi and actinomytes in the two fields decreased significantly, and 3-methylphenol enlarged this negative effect. 3-methylphonel had a negative effect on soil microbial diversity, but the increase of water supply could weaken this effect in intercropped field. The strongest allelopathic effect of 3-methylphenol was observed in mono-cropped field when the water supply was 75% of soil water hold capacity, while intercropping could maintain a relatively stable soil microbial diversity, compared to the mono-cropping with 3-methylphenol and low water supply. The allelopathic effect of 3-methylphenol was not significant on soil catalase activity, but significant on soil urease and phosphatase activities. Water supply level affected soil enzyme activity significantly, the lower the water supply level, the weaker the soil enzyme activity was. The interactions of water supply with 3-methyl phenol or cropping pattern were not significant, but intercropping could significantly affect the activities of soil catalase and phosphatase.

[Protective effects and their mechanisms of cobalt on soybean seedling's leaf under drought stress].

This paper studied the effects of cobalt on the polyamine content, reactive oxygen level, anti-oxidative enzyme activity, and cell membrane permeability of soybean seedling's leaf under drought stress, and discussed the mechanisms of these effects. The results showed that under drought stress, cobalt at its concentration of 30 micromol x L(-1) could significantly inhibit the production of ethylene. This concentration of cobalt had no significant effects on the contents of MDA and chlorophyll when the drought stress lasted 0 to approximately 12 days, but significantly restrained the increase of reactive oxygen level, hampered the decline of putrescine, spermidine and spermine contents and anti-oxidative enzyme activities,and thus,inhibited the accumulation of MDA and alleviated the reduction of chlorophyll content when the stress lasted 15 to approximately 21 days. It could be concluded that when soybean seedling's leaf was deeply stressed and damaged under drought stress, cobalt could alleviate the decline of polyamine content and anti-oxidative enzyme activity,and hence, alleviate the increment of reactive oxygen level and cell membrane's damage degree through inhibiting the production of ethylene, and exerted its protective effects on the soybean seedling's leaf under drought stress.

[Allelopathy of different plants on wheat, cucumber and radish seedlings].

By means of bioassay in laboratory and field, this paper studied the allelopathy of 18 kinds of plants in Gansu Province on the seedlings of wheat, cucumber and radish. The results showed that the aqueous extract of the stems and leaves of Artemisia annua, Solanum nigrum and Datura stramonium had the strongest allelopathy on test receptor plants, and their synthetic inhibitory effect (SE) was 47.66%, 32.89% and 26.63%, respectively. The SE of Xanthium sibiricum, Portulaca oleraca, Cephalanoplos segetum, and Chenopodium album was 21.71%, 20.93%, 20.83% and 20.2%, respectively, while Vicia amoena (SE 3.5%), Setaria viridis (SE 2.2%), and Cymamchum chinense (SE 1.97%) had a weaker allelopathy. Chenopodium ambrosioides (SE - 1.03%), Polygonum caespitosum (SE - 1.63%) and Avena fatua (SE 5.33%) had no evident allelopathy, but Artemisia annua affected the seedling height and fresh weight of radish, cucumber, wheat and maize, with the SE being 54.07%, 38.46%, 33.35% and 20.88%, respectively. Artemisia annua had a 44.70% of SE on wheat growth, and thus, had a certain value to develop and use.

[Temporal and spatial distribution characteristics of the crop root in intercropping system].

The ecological mechanism of competition and compensation between the crop root systems of two different intercropping patterns, wheat-soybean and corn-cabbage, was studied by field experiment. The results showed that the annual growth peak of wheat-soybean roots in intercropping was interlacing, the growth of root weight and length expressed synchronism, and the peak of root weight was appeared earlier than that of root length. The vertical distribution of the two crops' root system in two intercroppings was reduced gradually along with soil depths, which also showed that the multiple growth waves moved progressively. The root system distributed horizontally in intercropping system also showed a clearly unbalanced distribution. The root system distribution of out-row for corn elongated 20.4-40.8 cm to cabbage rows, but that of cabbage elongated only 8.5-12.6 cm to corn. The cross extent of root systems in corn-cabbage intercropping was decreased from 40.2 cm to 20.1 cm by fertilization, and the place of cross point for root concentrated region was changed from 20.5 cm to 12.4 cm below soil surface by fertilizer supply. The place of cross point for root concentrated region was an important index to decide the degrees of competition.

[Regulation of fertilizer application on yield and root growth of spring wheat-faba bean intercropping system].

The effects of N and P fertilizer application on the multiple population yield and root growth of spring wheat (Triticum aestivum)--spring faba bean(Vicia sativa)intercropping system were studied by two field experiments with 0, 150 and 225 kgN.hm-2, three pot and pool experiments with 2 N applications (0, 100 mg N.kg-1 soil) and 3 P applications (0, 100 and 200 mg P.kg-1 soil). The results showed that this intercropping system had a significant advantage of yield and beneficial effects. Compared to Po supply, P fertilization increased the seed yield by 48.39% for intercropped spring wheat and 16.69% for intercropped faba bean in field experiment. Furthermore, the total seed yield of both crops was increased by 20.07% to 43.14% in pool culture, and the grain yield of intercropped faba bean was increased by 58.46% to 78.78%. In the intercropping system, the growth peak of root density of both crops was appeared alternately, the peak of wheat root growth being earlier than that of faba bean. The maximum root weight of intercropped wheat was in its early heading periods, whereas that of faba bean appeared at its maturity periods, which reduced the competition for water and nutrients between the crops, and resulted in yield increase. The weight, length and surface area of wheat roots in P supply were increased by 54.33%, 48.88% and 47.00%, and in N supply, they were increased by 15.25%, 11.61% and 11.46%, respectively. About 57.61% of wheat root weight and 69.20% of faba bean root weight were distributed at 0-30 cm soil depths in the treatments of receiving P fertilizer at various rates, which indicated that P supply increased root weight and length of both crops in the intercropping system.