Influence of rates and sources of nitrogen on growth,nitrogen uptake and yield of cotton (G. hirsutum L.)

Field experiments on cotton with different forms of urea applied at rates of 40 and 80 kg N/ha were carried out. The results indicated that application of nitrogen increased plant height, dry matter accumulation, number of bolls per plant, seed cotton yield and nitrogen uptake. The proportion of dry matter and nitrogen in the stem was increased and that in the leaves was reduced by N application. Sulphur coated urea (all applied at sowing) was about the same in effect as N-Serve treated urea and gave significantly more seed cotton yield than untreated urea, neem cake treated urea and sulphur coated urea (applied in two splits). Nitrogen efficiency as expressed by kg seed cotton production per kg N applied was greater with 40 kg N/ha rate than with 80 kg N/ha. Sulphur coated urea (all applied at sowing) gave the highest nitrogen efficiency followed by N-Serve treated urea.     

Increase in the Nitrogen Content of Soil by the Introduction of Earthworms into Soil

The contribution of an earthworm species ( Amynthas vittatus ) to the increase of the nitrogen content of soil was examined. Three specimens of adult earthworms were introduced into 300 g of soil (Gray Lowland soil, silty clay) supplemented with 1% carboxymethyl cellulose in a container and incubated for 32 d at 22°C in the dark. The contents of total-N, NH₄-N and NO₃-N, and the population of aerobic nitrogen-fixing bacteria in soil significantly increased after incubation with the earthworms, while the natural abundance of ¹⁵N (δ¹⁵N) in soil decreased. The amount of nitrogen in the earthworms did not decrease during the incubation in the microcosm. Both acetylene reduction activity of the microcosm and incorporation of ¹⁵N to soil from atmospheric ¹⁵N₂ were significantly enhanced by the introduction of the earthworms into soil, though the observed increment of nitrogen in soil was much higher than the estimated one based on the nitrogen-fixing activity. The results obtained in the present study indicated that the earthworms increased the nitrogen content of soil, presumably due to the enhancement of the nitrogen-fixing activity of the soil from the microcosm by the earthworms.     

The effect of seeding and tillage methods on productivity of rice–wheat cropping system

Many farmers in southeast Asia are growing rice on unpuddled soil. This practice does not permit breaking of the deadlock of increase in productivity in spite of using high yielding varieties and practising all known scientific technologies. Furthermore, farmers do dry seeding which leads to heavy infestation of weeds and reduces response to other inputs. Similarly, in rice–wheat belt due to short turn around time farmers resort to broadcast sowing of wheat after rice and no data on benefits or otherwise of tillage are available. A field study was therefore conducted for 3 years (1993–1994 to 1995–1996) at the Indian Agricultural Research Institute, New Delhi to study the effect of tillage and seeding methods in rice–wheat cropping system. Treatments included four combinations of two puddling treatments (puddling and no puddling) and two methods of rice seeding (direct seeding and transplanting) in rice and two tillage treatments (zero and conventional tillage) in wheat. Results indicated that puddling increased grain yield of rice by 0.7–1 t ha⁻¹ and of succeeding wheat by 0.2–0.4 t ha⁻¹, straw yield of rice by 0.8–1.7 t ha⁻¹ and of succeeding wheat by 0.1–1.0 t ha⁻¹.

Puddling reduced water requirement of rice by 75 mm ha and increased net return of rice–wheat system by US $175 ha⁻¹. Transplanted rice gave significantly higher grain and straw yields and net returns than direct seeded rice both on puddled and unpuddled seedbed. Conventional tillage in wheat also increased productivity of rice–wheat cropping system significantly over zero tillage after both puddled and non-puddled rice. Our results thus show that rice should be grown on puddled soil and wheat after rice should be sown after conventional tillage.     

Hypothyroidism elicits electrophysiological noradrenergic subsensitivity in rat cerebellum

discharge rats of Purkinje neurons were compared in control and hypothyroid adult rats. Purkinje neurons in hypothyroid rats fired significantly faster and were less sensitive to iontophoretically applied norepinephrine than those in control rats. The subsensitivity of the Purkinje neurons appeared to be primarily due to an alteration in the beta-receptor--adenylate cyclase complex, because the sensitivity of these cells to locally applied N6-monobutyryl adenosine 3'-5'-monophosphate (N6 cyclic AMP) did not change significantly. The sensitivity of the Purkinje neurons to norepinephrine could be restored in hypothyroid rats by administration of triiodothyronine.     

Expression of lactate and malate dehydrogenases in tumors induced by SV40 and 7,12-dimethylbenz(a)anthracene

Isozyme patterns of lactate and malate dehydrogenases were studied in tumors induced by SV40 and 7,12-dimethylbenz(a)anthracene and in established cultures of cells from these tumors. The expression of B polypeptide subunits of lactate dehydrogenase is suppressed similarly by both agents. This may be due to inactivation of the gene at the locus determining the B polypeptide subunit. Malate dehydrogenase isozyme patterns are not changed significantly by the virus or the carcinogen.     

Is the gramicidin a transmembrane channel single-stranded or double-stranded helix? A simple unequivocal determination

Thallium ion-induced carbonyl carbon chemical shifts were compared for all of the L-residue-peptide carbonyl carbons of the gramicidin A transmembrane channel. Molecular structures were deduced by using the argument that helically equivalent and equally proximal carbonyls would exhibit essentially equivalent ion-induced chemical shifts. The transmembrane channel was found to be a head-to-head dimer with the structure of a left-handed, single-stranded beta-helix.     

Lhx2 selector activity specifies cortical identity and suppresses hippocampal organizer fate

The earliest step in creating the cerebral cortex is the specification of neuroepithelium to a cortical fate. Using mouse genetic mosaics and timed inactivations, we demonstrated that Lhx2 acts as a classic selector gene and essential intrinsic determinant of cortical identity. Lhx2 selector activity is restricted to an early critical period when stem cells comprise the cortical neuroepithelium, where it acts cell-autonomously to specify cortical identity and suppress alternative fates in a spatially dependent manner. Laterally, Lhx2 null cells adopt antihem identity, whereas medially they become cortical hem cells, which can induce and organize ectopic hippocampal fields. In addition to providing functional evidence for Lhx2 selector activity, these findings show that the cortical hem is a hippocampal organizer.     

Effect of gamma-irradiation on the lipid profile of nutmeg (Myristica fragrans Houtt.)

The effect of gamma-irradiation on the lipid constituents of nutmeg (Myristica fragrans) was examined at radiation doses between 2.5 and 10 kGy. The fatty acid composition of the triacylglycerol, the major lipid component, was found to be made up of myristic (90%), palmitic (6%), lauric (3%), petroselinic (0.13%), and stearic acids (0.5%) as determined by gas chromatography-mass spectrometry. A dose-dependent decrease in the triacylglycerol content and a concomitant increase in free fatty acids characterized the lipid profile of the irradiated spice. This suggested a breakdown of acylglycerols during radiation processing, resulting in the release of free fatty acids. These changes were found to be significant at doses above 5 kGy. The impact of the above changes on the flavor of the spice is discussed. These studies suggest that radiation processing of nutmeg should be limited to a dose of 5 kGy.     

Breeding distribution and maternal genetic lineages in Lulu,a dwarf cattle population in Nepal

Lulu is a dwarf cattle population bred in the Mustang district of western and central Nepal. This area is located around the habitat boundary between Bos taurus and Bos indicus. The peculiarities of Lulu are their small size (weight range in the adult female: 68–153 kg) and rearing in high mountain areas at 2800 m to 4000 m in altitude. There were 5770 head of Lulu cattle in the Mustang district in 1998, 4333 females and 1437 males. The morphological appearance of Lulu is Bos taurus. However, one of the five Lulu studied in Kagbeni, Mustang had a Bos indicus mitochondrial DNA type based on the D‐loop sequence, while the other four were Bos taurus. It is suggested that there are hybrids of Lulu with Bos indicus maternal lineage in a mostly taurine‐breed genetic background. Steps must be taken to preserve the unique Lulu.