The Effects of Intercrop Spacing Patterns on the Silage Yield of Maize and Soybean

The effects of intercrop spacing patterns on the silage yields of both maize (lea mays L.) and soybean (Glycine max [L.] Merr.) were examined from 1985 to 1987. Dwarf maize was intercropped with nonnodulatmg or nodulating soybean in the spacing patterns, S_40same (two crops in the same row, 40 cm row width) and S_20ait or S_40ak (two crops in alternate rows, 20 cm or 40 cm row width, respectively). Tall maize was intercropped with nodulating soybean in S_40sames S_40alt and S_40pair (maize in 40 cm paired rows, soybean rows 20 cm outside each maize row and 80 cm from the next set of four rows) at 0 or 60 kg N ha⁻¹ and at population densities of 67% maize: 67% soybean or 50 % maize: 50% soybean. Maize and soybean were also intercropped and stripcropped on a farm-scale. The only difference between intercrops arranged in the same rows versus those in alternate rows was that the average soybean protein yields were higher in S_40same than in S_40alt. In 1986, the S_40alt maize-soybean intercrops produced higher maize yields, total biomass yields and Land Equivalent Ratios (LERs) than in S_40pirs, and in 1987, these responses were higher in intercrops than in stripcrops. In 1986, at 0 kg N ha⁻¹, the soybean biomass and protein yields were lower in S_40alt, than in S_40pairs and in 1987, these responses were lower in intercrops than in stripcrops.     

The effect of quality of grass and maize silage on the intake and performance of beef cattle

A study was undertaken to evaluate the effects of incorporating high (HMS) and low (LMS) maturity maize silages into diets based on low (LGS) and high (HGS) feed value grass silages offered to beef cattle. Seventy-two continental cross-bred steers were used in a 14-week continuous design, randomised block experiment. The six treatments were arranged as a 2 × 3 factorial design incorporating the LGS and HGS offered as the sole forage, along with each of the two grass silages offered in a 60:40 ratio (DM basis) with the HMS and LMS. All diets were supplemented with 3 kg/head/day concentrates. Total daily DM and metabolisable energy intakes were higher (P < 0.001) for diets based on HGS compared to those based on LGS. Intakes were similar (P > 0.05) between diets containing LMS and HMS, both of which were higher (P < 0.001) than diets containing grass silage as the sole forage. Highest DM intakes were recorded with a mixture of HGS and HMS (P < 0.05 or greater). Cattle offered diets containing HGS had higher live-weight gain (P < 0.05), final live weight, carcass gain and carcass weight (P < 0.001) than those offered diets containing LGS. Feed conversion efficiency, assessed on a carcass gain basis, was poorer (P < 0.05) with diets containing LGS compared with those containing HGS, though differences between diets containing either LMS or HMS and GS as the sole forage were not significant (P > 0.05).     

不同高羊茅品种夏季高温季节的坪用性状研究

比较不同高羊茅品种在南京地区越夏期间坪用性状的变化,结果表明：高羊茅在高温胁迫期间叶片变窄,叶色值降低,盖度、密度下降,表观质量降低;供试的14个高羊茅品种可以分为三类：第一类是TF07、TF08、TF10和TF18四个品种,耐热性弱;第二类是TF06、TF11、TF12、TF13、TF14、TF16和TF19,耐热性中等;第三类是TF01、TF03和TF05,耐热性强。     

紫花苜蓿品种在河北低平原区的引进筛选试验研究

在河北低平原区对引进的11个紫花苜蓿品种进行了三年的比较试验。结果表明：保定苜蓿鲜草产量最高，其次是中苜1号、WL323ML；中苜1号干草产量最高，其次是WL323ML、保定苜蓿；WL323ML粗蛋白质产量最高，其次是顶点、中苜1号。保定苜蓿、中苜1号株高、鲜干比、茎叶比明显较低。保定苜蓿、中苜1号抗涝性较强，但抗倒性较差。各品种抗寒性、抗旱性均较强，无明显差异。综合分析WL323ML表现最优，宜作为河北低平原区进行推广的首选品种。     

Distribution and relative importance of lepidopteran cereal stemborers and their parasitoids in Uganda

Infestation levels and parasitism of lepidopteran stemborers on maize were assessed in four agroecological zones (AEZ) in Uganda. The indigenous noctuidBusseola fusca Fuller (Noctuidae) and the invasiveChilo partellus Swinhoe (Crambidae) were the most important stemborers recorded.C. partellus represented 77% of the stemborers in the Eastern AEZ whileB. fusca was dominant in the other AEZs, accounting for 60–79%. The proportion of infested plants was between 16% and 45% and borer density between 0.2 and 1.0 borers per plant. There was no clear relationship between damage and stem tunneling, which is often used to estimate yield loss.Telenomus busseolae Gahan (Scelionidae), the only egg parasitoid recovered, caused parasitism of up to 46% onB. fusca eggs. Several larval and pupal parasitoid species were recorded. The most common were the indigenous braconidCotesia sesamiae and the introducedCotesia flavipes, which are larval parasitoids ofB. fusca andC. partellus, respectively. Mean parasitism by the indigenousC. sesamiae ranged between 2.0% and 29.4% onB. fusca and from 0 to 13% onC. partellus. C. flavipes was recovered at most locations with parasitism of 0–30.5% onC. partellus and 0–12% onB. fusca; the latter was probably the result of multiparasitism as laboratory studies have shown that it was not a suitable host forC. partellus. Results indicated further that the parasitoid has not attained equilibrium 5 years after its introduction. http://www.phytoparasitica.org posting Nov. 20, 2006. Teddy Matama-Kauma died suddenly in an accident on Dec. 10, 2006, while this paper was in press.     

Water and nitrogen interaction on soil profile water extraction and ET in maize-wheat cropping system

In the present study, water and nitrogen interaction on soil profile water extraction and evapo-transpiration (ET) was investigated taking a field experiment on a clay loam soil (Typic Haplustept) at the Indian Agricultural Research Institute, New Delhi with four consecutive crops (maize-wheat-maize-wheat) taken from July 2002 to April 2004. Three levels of water regime, namely W1, W2 and W3 referring to limited, medium and maximum irrigation were applied to each crop depending on the seasonal rainfall and the critical crop growth stage. The three water regimes were used with five nitrogen levels from T1 to T5, (T1, 0% N; T2, 75% N; T3, 100% N; T4, 150% N; T5, 100% N from organic source) in a split plot design for the four crops grown in sequence.Significant water and nitrogen interaction was observed for ET and soil profile water extraction pattern. Averaged across nitrogen treatments, ET in W2 and W3 were higher by 17 and 26%, respectively than W1 in maize 2002 and by 12 and 19% in maize 2003. In case of wheat, ET in W2 and W3 were higher by 27 and 58% than W1 in 1st crop and by 37 and 70% in 2nd crop. The effect of nitrogen regime, however, was prominent in both crops of maize and wheat, with significantly higher profile soil moisture depletion in T4 of each water regime. In all cases, lowest water depletion was observed in control plots receiving 0% N.In both crops, water extraction from surface 60 cm was highest in W3 followed by W2 and W1. In maize, the % extraction from 0 to 60 cm layer varied from 71 to 76% (W1), 70-79% (W2) and 75-82% (W3), whereas the values for wheat were 70-77, 72-79 and 75-83% for W1, W2 and W3, respectively. The 90-120 cm layer contributed only 3-14% to total water extraction in both the crops. From 90 to 120 cm layer, higher extraction was observed in W1 as compared to W3. The extraction values in W1, W2 and W3 in maize were 9-13, 7-14 and 3-9, respectively, whereas the corresponding values in wheat were 8-14, 5-12 and 3-7% for the three water regimes. Effect of nitrogen treatments on water extraction from deeper layer was observed with higher extraction in highest fertilized treatment (T4) as compared to other treatments.     

Does the Sulfur Assimilation Pathway Play a Role in the Response to Fe Deficiency in Maize (Zea mays L.) Plants?

Abstract

The finding that the methionine is the sole precursor of the mugineic acid family phytosiderophores induced us to evaluate whether sulfur assimilation pathway has a role in plant response to Fe deficiency. Maize plants were grown for 10 days in nutrient solution (NS) containing 80 µM Fe in the presence (+S) or absence (?S) of sulfate. After removing the root extraplasmatic iron pool, half of the plants of each treatment (+S and ?S) were transferred to a new Fe deficient NS (0.1 µM final Fe concentration) (?Fe). The remaining plants of each pre‐culture condition (+S and ?S) were transferred to a new NS containing 80 µM Fe (+Fe). Leaves were collected 4 and 24 hours from the beginning of Fe deprivation period and used for chemical analysis and enzyme assays. Results showed that iron content in the leaves was lower in plants grown in S‐deficiency than in those grown in the presence of the macro‐nutrient. Iron deprivation produced an increase in the level of SH compounds in both nutritive conditions (+S and ?S). These observations are suggestive of some relationship between S nutrition and Fe uptake. For this reason, we next investigated the influence of Fe availability on S metabolism through the evaluation of changes in ATPs and OASs activity, the first and the last enzyme of S assimilation pathway respectively. Results showed that S‐starvation increased the activity of both enzymes, but this effect disappeared in plants upon Fe deficiency suggesting that S metabolism is sensitive to Fe availability. Taken together these evidences suggest that S metabolism is sensitive to soil Fe‐availability for plant nutrition and support the hypothesis of S involvement in plant response to Fe deprivation.     

玉米温光敏雄性不育系9417叶片叶绿体蛋白质差异分析

对玉米温光敏感雄性不育-可育 “两用系”9417的不育型和可育型叶片中的叶绿体蛋白质组进行研究，试图找出不育型与可育型的差异蛋白,确定导致不育的蛋白。利用SDS PAGE凝胶电泳，对玉米雄性不育 可育“两用系”不育型与可育型8叶期功能叶叶绿体蛋白质组中的差异蛋白进行分析。结果表明，不育型与可育型存在3条蛋白差异条带，其中No.1条带为不育型中新出现的蛋白质条带，而其余两条条带只在表达丰度上有差别。利用MALDI TOF MS方法，运用MASCOT软件于NCBI数据库中进行数据查询，结果显示No.1条带中含有3种蛋白质，而这3种差异蛋白的出现可能与玉米不育性有关。     

Subsurface drip irrigation of corn in the United States Mid-South

Although rainfall in the United States Mid-South is sufficient to produce corn (Zea mays L.) without irrigation in most years, timely irrigation has been shown to increase yields. The recent interest in ethanol fuels is expected to lead to increases in US corn production, and subsurface drip irrigation (SDI) is one possible way to increase application efficiency and thereby reduce water use. The objective of this study was to determine the response of SDI-irrigated corn produced in the US Mid-South. Field studies were conducted at the University of Arkansas Northeast Research and Extension Center at Keiser during the 2002-2004 growing seasons. The soil was mixed, with areas of fine sandy loam, loamy sand, and silty clay. SDI tubing was placed under every row at a depth of approximately 30 cm. Three irrigation levels were compared, with irrigation replacing 100% and 60% of estimated daily water use and no irrigations. The split plot treatment was hybrid, with three hybrids of different relative maturities. Although the 3-year means indicated significantly lower yields for a nonirrigated treatment, no significant differences were observed among the treatments in 2003 or 2004. A large difference was observed in 2002, the year with the least rainfall during the study period, but no difference was detected between the two irrigated treatments in any year. The treatment with the lower water application had the higher irrigation water use efficiency. Although the results of this study suggested that replacing 60% of the estimated daily evapotranspiration with SDI is sufficient for maximum corn yields, additional observations will be needed to determine whether corn production with SDI is feasible in the region and to develop recommendations for farmers choosing to adopt the method. Improved weather forecasting and crop coefficient functions developed specifically for the region should also contribute to more efficient irrigation management.     

基于双目立体视觉的苗期玉米株形测

将田间正常生长的待测玉米植株带土移至测定台上,标定双目立体视觉系统,提取、分割叶片图像,以Douglas-Peucker多边形法逼近叶片边缘,去除两幅对应图像中没有匹配关系的多边形顶点,结合投影矩阵计算出叶片边缘点的三维坐标.分别投影叶片边缘点到植株平面和植株水平平面,对投影的离散点分段二次拟合、Cardinal样条插值,得到代表叶片形状的曲线,计算出叶长、叶片着生高度、茎叶夹角、叶片方位角等株形指标.测量实验表明,本方法快速、准确、自动化程度高,能够满足苗期玉米株形测量的要求.