Physico-chemical characteristics of apricot (Prunus armeniaca L.) grown in Northern Areas of Pakistan

In order to ascertain physico-chemical, functional and geometrical traits of apricot fruit from Northern Areas of Pakistan, six predominantly grown varieties namely, Alman, Habi, Khakhas, Mirmalik, Neeli and Shai were selected in this study. Proximate composition as crude fat (2.1–3%), crude protein (6.18–8.7%), crude fiber (11.85–13.6%), ash (9.45–12.1%) and total sugars (56.8–64.9%) were determined on dry weight basis. The data showed variations among the investigated parameters in all varieties. Functional properties of apricot fruit viz. ascorbic acid (67.39–90.94 mg/100 g), total phenolic compounds (4590–7310 mgGAE/100 g), total carotenoids (10.09–18.13 mg/100 g β-carotene) and antioxidant activity (56.84–82.33%) were also recorded. The data pertaining to mineral contents (mg/100 g) revealed K as the predominant element (2040–3000) followed by P, Mg, Ca, Na and Fe among all the tested samples. Furthermore, geometrical characters of apricot varieties were also determined as important sensory and technological attributes on fresh weight basis. The result from the present study showed that all the tested varieties are highly nutritious and rich in functional components.     

Cross‐resistance,mode of inheritance and stability of resistance to emamectin in Spodoptera litura (Lepidoptera: Noctuidae)

BACKGROUND: Spodoptera litura (F.) is a cosmopolitan pest that has developed resistance to several insecticides. The aim of the present study was to establish whether an emamectin‐selected (Ema‐SEL) population could render cross‐resistance to other insecticides, and to investigate the genetics of resistance. RESULTS: Bioassays at G₁ gave resistance ratios (RRs) of 80‐, 2980‐, 3050‐ and 2800‐fold for emamectin, abamectin, indoxacarb and acetamiprid, respectively, compared with a laboratory susceptible population Lab‐PK. After three rounds of selection, resistance to emamectin in Ema‐SEL increased significantly, with RRs of 730‐fold and 13‐fold compared with the Lab‐PK and unselected (UNSEL) population respectively. Further studies revealed that three generations were required for a tenfold increase in resistance to emamectin. Resistance to abamectin, indoxacarb, acetamiprid and emamectin in UNSEL declined significantly compared with the field population at G₁. Furthermore, selection with emamectin reduced resistance to abamectin, indoxacarb and acetamiprid on a par with UNSEL. Crosses between Ema‐SEL and Lab‐PK indicated autosomal and incomplete dominance of resistance. A direct test of a monogenic model and Land's method suggested that resistance to emamectin was controlled by more than one locus. CONCLUSION: Instability of resistance and lack of cross‐resistance to other insecticides suggest that insecticides with different modes of action should be recommended to reduce emamectin selection pressure. Copyright © 2010 Society of Chemical Industry     

Driving factors of soluble organic nitrogen dynamics in paddy soils: Structure equation modeling analysis

Soil soluble organic nitrogen (SON) is one of the most active components in soil nitrogen pools; however, limited information is available with regard to its driving factors, as well as their pathways and degrees of influence. In this study, structural equation modeling was used to analyze the driving factors, their significance, and pathways that affected SON dynamics in a waterlogged experiment of two typical paddy soils incubated for 80 d after green manure application. Soil pH, Eh, microbial biomass, enzyme activity, and SON dynamics were used to construct the structural equation model. Results showed that soil microbial biomass carbon (MBC), protease, glutamine, and initial organic matter (OM) directly and significantly affected soil SON with path coefficients corresponding to 0.405, 0.547, 0.523, and -0.623 (P < 0.01), respectively. Soil microbial biomass carbon and initial OM affected the SON dynamics indirectly through protease and glutamine activity. In addition, pH indirectly affected SON dynamics by glutamine activity. It is implied that soil MBC, protease, glutamine, and initial OM are the key factors affecting SON dynamics in the waterlogged paddy soils after green manure application. Our research indicated that structural equation modeling could provide an effective method to clearly recognize the impact, significance, and pathways of multiple factors on SON dynamics in paddy soils.     

Trace elements accumulation in soil and rice plants irrigated with the contaminated water

We carried out a study to see the effect of contaminated water of Nullah Dek on fine rice paddy and straw yields and trace elements accumulation in different parts of rice plants and soil. A site was selected near the bank of Nullah Dek at Kot Pindi Das in the District of Sheikhupura, Pakistan. The water of this nullah is contaminated by industrial effluents carrying different micronutrients. This water was employed to grow rice crop. Water samples were collected before transplanting and during the season with 15 days interval for analysis from 20 July to 1 November 2002 from a spot near village Shamke. Three fine rice varieties, viz. Super Basmati, Shaheen Basmati and Basmati 2000 were transplanted. These rice varieties were grown up to maturity. Paddy and straw yields data were recorded. Six composite soil samples from three random spots were collected from the experimental site before the start of the study to see the status of trace elements in soil. After the harvest of rice crop, soil, paddy and straw samples were analysed for Zn, Cu, Fe and Mn. The chemical analysis of Nullah Dek water showed that total salts concentration was greater than the safe limit, i.e. electric conductance (EC) > 1.0 dS m⁻¹. Even sodium adsorption ratio (SAR) was very high, but there was no problem of high residual sodium carbonate (RSC). Zn, Cu, Fe and Mn were present but within safe limits. The water of Nullah Dek remained within permissible limits of irrigation from onset of rainy season till 15 October. There was an increase in EC, SAR and trace elements concentrations after 15 October but within safe limits. Soil analysis revealed its saline nature, devoid of sodicity. Among trace elements, the zinc ranged between deficiency (<0.5 mg kg⁻¹) and adequate limits (>1.0 mg kg⁻¹). Copper, Mn and Fe were present in adequate amounts. After the harvest of rice crop there was a slight decrease in pH, EC_e and SAR at both the depths, while the concentrations of all trace elements were slightly increased with more in upper layer than the lower layer. Shaheen Basmati produced the maximum paddy yield followed by Basmati 2000 and then Super Basmati. The chemical analysis of paddy samples indicated a sufficient accumulation of zinc (1.68–1.78 mg kg⁻¹), copper (1.38–1.45 mg kg⁻¹), iron (6.12–6.37 mg kg⁻¹) and manganese (2.22–2.42 mg kg⁻¹). Analysis of rice straw also showed sufficient accumulation of zinc (27.50–28.50 mg kg⁻¹), copper (20.0–20.50 mg kg⁻¹), iron (270–280 mg kg⁻¹) and manganese (2.38–2.41 mg kg⁻¹).     

陆地棉亲本间遗传距离与杂种优势的相关性研究

【目的】通过1 500个陆地棉杂交组合分析杂种优势与其亲本间数量性状遗传距离的相关性,探讨能否利用大规模杂交组合亲本间遗传距离提高陆地棉杂种优势预测效果,以期为棉花杂交育种和杂种优势利用提供理论指导。【方法】选择来自15个国家和中国23个省（市）的305份陆地棉核心种质为亲本,采用L×T（Line×Tester）杂交设计配制1 500个杂交组合。2012—2013年,在中国南北方13个生态环境下考察其株高、单铃重、衣分、纤维长度等10个产量和纤维品质相关性状,分析F₁杂种优势、亲本间遗传距离和群体结构,并采用4种方式（Cor1—Cor4）计算遗传距离与杂种优势的相关性。【结果】10个性状中亲优势（MPH）均值的变幅为1.70%—7.40%,平均为4.36%,按父本不同将F₁分成5组（A,E）,其MPH均值A>E>B>C>D;超亲优势（HB）均值的变幅为-4.17%—1.87%,平均为-0.17%,A、B和E组的HB均值皆为正。10个性状在5组中除D、E组的马克隆值之外,其他性状普遍具有明显的中亲优势,其中,单铃重和纤维长度的中亲优势在5组中均以正优势为主（达80%以上）,最大值分别为34.01%和9.83%,对应的超亲优势分别为24.25%和5.80%。F₁和亲本差异显著性分析表明单铃重、株高、纤维长度、伸长率和整齐度指数整体表现出一定的超亲优势。父本（测试种）与300个母本之间的遗传距离介于2.280—61.430,平均为21.550,5个测试种与母本间的平均遗传距离D>C>E>A>B,其中,最近值为11.721,最远值为33.271。按最小方差聚类,将305个陆地棉亲本划分为2个主群,包括5个亚群。4种遗传距离与杂种优势的相关性分析结果显示,因样本量、遗传距离变幅和父本不同其结果有所差异,相关性随样本量的增大而有所增强。其中,Cor1是Cor2结果的整体体现;Cor3与Cor1和Cor2相比,部分性状的中亲优势与遗传距离的相关性有所不同;Cor4的相关性最弱。综合来看,遗传距离与衣分、断裂比强度、整齐度指数和纺纱均匀性指数的中亲优势呈显著正相关,遗传距离与其他性状的中亲优势的相关性因采用的分析方案不同,结果有所不同;在4种方案中,除整齐度指数外,遗传距离与超亲优势的相关性整体表现负相关。其中,遗传距离与马克隆值、纤维长度和衣分的超亲优势相关性较强。【结论】陆地棉亲本间数量性状遗传距离与杂种优势有一定的线性关系,不同性状的杂种优势与遗传距离的相关性存在正负和强弱差异,且样本量越大相关性越强。说明基于大规模杂交组合研究陆地棉亲本间遗传距离与杂种优势的关系效果显著。