Effect of pod zone moisture content on reproductive growth in three cultivars of peanut (Arachis hypogaea)

Very little research has been done to investigate the effect of a dry podding zone on reproductive development in peanut plants that are otherwise well hydrated via subsoil moisture extraction. The influence of podding zone moisture content on reproductive development and growth of three peanut cultivars (McCubbin, Gajah and Robut 33-1) was investigated in pots grown in the glasshouse. In two cultivars (McCubbin and Gajah) seed yield was reduced in a dry (air-dry) compared to a wet (field capacity) podding zone. Seed yield of Robut 33-1 was unaffected by podding zone moisture content, indicating that cultivar variation in reproductive performance in response to podding zone moisture may exist.     

Microculture of single protoplasts of Brassica napus

Protoplasts of Brassica napus L. were cultured individually in a microdroplet system using a synthetic medium with survival rates of more than 70% and division frequencies of up to 65%. Microcallus formation occurred at frequencies of up to 50%. Factors affecting the survival and division of individually cultured protoplasts, such as composition and volume of culture medium, pH, buffering system, osmolarity and genotype, were analyzed.     

Phenolic acid effects on peanut growth and oil production

Plants of peanut (Arachis hypogaea L. var. PG No. 1) were given two foliar sprays of phenolic compounds (H-acid, 1, 2, 4-acid, resorcinol and RD-Brown) at 100 and 200 ppm, 35 and 50 days after sowing. In treated plants, shelling %, yield (kg/ha), number of gynophores per plant and number of pods per plant were significantly greater than in the control. Oil content of kernels also showed a significant increase with all the phenolic compounds applied. These compounds increased the linoleic acid concentration so improving nutritional quality. The number of gynophores was significantly correlated with the number of pods per plant and yield per hectare. The effect of phenolic compounds on growth and development was independent of their structural configuration.     

Enhanced plant regeneration from microspore-derived embryos of Brassica napus by chilling,partial desiccation and age selection

Germination was readily induced in recalcitrant microspore-derived embryos of Brassica napus Topas when they were exposed to a period of chilling (9–12 days at 4°C) or partial desiccation (rapid or slow air drying) prior to germination. In general, embryos thirty-five days old had the highest germination rates as compared to younger or older ones. Populations of embryos were induced to germinate at a rate of over 90% under specific temperature, desiccation and age conditions. Comparisons to an embryogenic B. napus winter line, F346, are made.     

Temperature influence on cohort parameters and demographic characteristics of the two cowpea coreids Clavigralla tomentosicollis and C. shadabi

Age-specific life tables of two important pests of cowpea, Vigna unguiculata (L.) Walp., the pod sucking bugs Clavigralla tomentosicollis Stål and C. shadabi Dolling (Heteroptera: Coreidae), were obtained from observations carried out at different temperatures. A biophysical model was found satisfactory to describe the temperature-response of developmental and mortality rates of egg and nymphal stages, with a peak developmental rate around 34°C in both species. The variability in development times was small and the experimental data did not permit any conclusion with regard to the Erlang probability density function. Survival of eggs and nymphs remained high between 20° and 30°C for both species. At temperatures above 34°C, C. tomentosicollis survivorship and fecundity was higher than that of C. shadabi, which in turn laid more eggs at temperatures between 20° and 30°C. Maximum fecundity is estimated to be at 29°C for C. tomentosicollis (99 eggs/female) and 26°C for C. shadabi (261 eggs/female). At 30°C, the intrinsic rate of increase reached a maximum in both species, 0.152 per day for C. tomentosicollis and 0.145 per day for C. shadabi, and remained high for C. tomentosicollis until 36°C. C. tomentosicollis performed significantly better on pigeonpea, Cajanus cajan Millsp., than on cowpea at higher temperatures.     

Hydrolysis products of glucosinolates in Brassica napus tissues as inhibitors of seed germination

Enzymatic hydrolysis of glucosinolates, a class of compounds found in Brassica species, results in a number of products with potential to inhibit seed germination. To investigate the impact of both volatile and water-soluble allelochemicals, germination bioassays using Lactuca sativa seeds were conducted with root and combined leaf and stem tissues of Brassica napus. Tissues in which glucosinolates were hydrolyzed to remove volatile glucosinolate degradation products were compared with intact tissues and water controls. Only tissues containing glucosinolates produced volatiles that inhibited germination. Volatiles were trapped and identified using GC-MS. Volatiles produced in greater quanitity from intact tissues than from tissues without glucosinolates were almost exclusively glucosinolate hydrolysis products. Water-soluble components also inhibited germination. Chemical analysis of extracts confirmed the presence of glucosinolate hydrolysis products, but indicated the involvement of additional allelochemicals, especially in leaf and stem tissues. Results support the proposal that glucosinolate-containing plant tissues may contribute to reductions in synthetic pesticide use if weed seeds are targeted.Abbreviations ITC isothiocyanates - CN organic cyanides - OZT oxazolidinethione - iRoot intact root tissue - iL&S intact leaf and stem tissue - hRoot hydrolyzed root tissue - hL&S hydrolyzed leaf and stem tissue     

Seed development in Pisum

The Ih and lh _i alleles have been shown previously to reduce the level of endogenous gibberellin A₁ (GA₁) in shoots of pea (Pisum sativum L.), resulting in a dwarf phenotype compared with the wild type, cv. Torsdag (Lh). In addition, plants homozygous for the lh ⁱ allele have reduced seed yield compared with Lh (tall, wild type) and lh (dwarf) plants. In this paper we show that the lh ⁱ mutation is expressed in developing seeds and pods. Comparison of GA levels in young shoots and developing seeds of genotypes lh and lh ⁱ demonstrates that the relative severity of the two mutations varies in different tissues. Homozygous h ⁱ seeds have reduced GA levels, weigh less, and are less likely to develop to maturity when compared with Lh seeds. However, fertilization of lh ⁱ plants with Lh pollen increases seed GA levels, seed weight and seed survival, indicating that an increase in seed GA levels due to the presence of the Lh allele can restore normal seed growth. Pods developing on self-pollinated lh ⁱ plants are shorter than pods on Lh (wild type) plants, although this may be an indirect effect of the increased seed abortion of lh _i plants. Based on these results we suggest that endogenous GAs play an important role in the development of seeds of P. sativum L.Abbreviations GA_(n) gibberellin A_n We wish to thank Katherine McPherson, Peter Newman, Leigh Johnson and Peter Bobbi for technical assistance, Professor L. Mander (ANU, Canberra) and Professor B.O. Phinney (UCLA, USA) for labelled GA standards, and the Australian Research Council for financial support.     

Binding-protein expression is subject to temporal,developmental and stress-induced regulation in terminally differentiated soybean organs

Binding protein (BiP) is a widely distributed and highly conserved endoplasmic-reticulum luminal protein that has been implicated in cotranslational folding of nascent polypeptides, and in the recognition and disposal of misfolded polypeptides. Analysis of cDNA sequences and genomic blots indicates that soybeans (Glycine max L. Merr.) possess a small gene family encoding BiP. The deduced sequence of BiP is very similar to that of other plant BiPs. We have examined the expression of BiP in several different terminally differentiated soybean organs including leaves, pods and seed cotyledons. Expression of BiP mRNA increases during leaf expansion while levels of BiP protein decrease. Leaf BiP mRNA is subject to temporal control, exhibiting a large difference in expression in a few hours between dusk and night. The expression of BiP mRNA varies in direct correlation with accumulation of seed storage proteins. The hybridization suggests that maturing-seed BiP is likely to be a different isoform from vegetative BiPs. Levels of BiP protein in maturing seeds vary with BiP mRNA. High levels of BiP mRNA are detected after 3 d of seedling growth. Little change in either BiP mRNA or protein levels was detected in maturing soybean pods, although BiP-protein levels decrease in fully mature pods. Persistent wounding of leaves by whiteflies induces massive overexpression of BiP mRNA while only slightly increasing BiP-protein levels. In contrast single-event puncture wounding only slightly induces additional BiP expression above the temporal variations. These observations indicate that BiP is not constitutively expressed in terminally differentiated plant organs. Expression of BiP is highest during the developmental stages of leaves, pods and seeds when their constituent cells are producing seed or vegetative storage proteins, and appears to be subject to complex regulation, including developmental, temporal and wounding.The mention of vendor or product does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over vendors of similar products not mentioned.Abbreviations BiP binding protein The sequences reported in this paper have been submitted to Gen-Bank and are identified with the accession numbers BiP-A (U08384), BiP-B (U08383), BiP-C (U08382) and -1,3 glucanase (U08405).     

The K/Na and Ca/Na ratios and rapeseed yield,under soil salinity or sodicity

Rapeseed (Brassica napus) is a crop relatively tolerant to salt and sodium. Our objective was to study the interactions between Na, K and Ca and their relationship with its yield under the isolated effects of soil salinity or sodicity.Two experiments were carried out using pots filled with the Ah horizon of a Typic Natraquoll. There were three salinity levels (2.3 dS m^-1; 6.0 dS m^-1 and 10.0 dS m^-1) and three sodicity levels, expressed as sodium adsorption ratios (SAR: 12; 27 and 44). The soil was kept near field capacity.As soil salinity increased, the K/Na and Ca/Na ratios in the tissues decreased markedly but yields and aerial biomass production were not affected. As soil SAR value increased, the K/Na and Ca/Na ratios in plants and K-Na and Ca-Na selectivities decreased. Plants could not maintain their Ca concentration in soil with a high SAR. The grain yield and biomass production diminished significantly in the highest SAR treatment. Our results are consistent with those showing detrimental osmotic effects of salts in Brassica napus. Conversely, under sodicity, the K/Na and Ca/Na ratios in plant tissues decreased considerably, in accordance with grain and biomass production. These results show that the effects of sodicity are different from those of salinity.