Twenty strains of Eragrostis curvula, together with E. plana, Chloris gayana and Digitaria smutsii, have been compared on the basis of (a) herbage yields and (b) nitrogen, phosphate and potash composition and yield, from broadcast stands in a randomized block experiment over two seasons. The strains of E. curvula were grouped into types for which the names Curvula, Robusta Blue, Robusta Green, Robusta Intermediate, and Chloromelas were used. Significant differences were demonstrated in herbage yield between certain of these types, but there were no clear differences in nitrogen content. Chloris, Digitaria and the three Robusta types had the highest phosphate and potash content, whereas the Chloromelas type and E. plana were intermediate and the Curvula type was lowest in these constituents. Robusta Green, Robusta Intermediate and Curvula types had the highest nitrogen yield, Robusta Green and Robusta Intermediate types the highest phosphate yield, and Robusta Intermediate and Robusta types the highest yield of potash. The superiority of types other than Curvula (Ermelo and Tanganyika strains), and the need for research on the types, has been demonstrated.

The weights of the branches, stems and roots of two or three year old arabica coffee trees were compared with the diameters of the stumps or stems and with the heights of the trees. No formula could be derived, relating the weight of the plants to one or more non-destructive observations, which was valid for all three treatments to which the trees had been subjected, i.e. stripped of crop when two years old, cropping when two years old, and bearing a crop when three years old. Bearing a crop when two years old resulted in thin, light stems and a poor root system.

Trials were carried out to ascertain which of four systemic insecticide/nematicides were absorbed by young coconut palms (Cocos nucifera L.) using three different methods of application. Stem injection of Bidrin and Nemacur are impractical because the chemicals break down too quickly and frequent retreatment would result in too much physical damage to the young trees. Lannate was not absorbed from leaf axil placement, and broke down too quickly when absorbed from the soil to be of practical use. Nemacur was not absorbed through the leaf axil, but was from the soil and lasted up to 14 weeks in the plant. Temik, absorbed both through the leaf axil and from the soil, lasted up to 14 weeks. The possibility of controlling red ring disease of coconuts with Nemacur or Temik is considered.

A field experiment to study the response of pop corn (Zea mays Everta) to various levels of nitrogen and plant population was undertaken at the Research Station, Bajaura (HP) during kharif 1974 and 1975. Increases in nitrogen level from 0 to 60 kg N/ha increased grain yield significantly by 54·8%, but yield differences between 60 and 90 kg N/ha were non-significant. Various plant densities did not affect yield significantly. Yield-contributory characters were significantly influenced by treatments and were interrelated with yield under the influence of nitrogen and plant population levels.

Sucrose yield in sugarcane is a complex process regulated by both environmental and endogenous factors. However, the metabolic balance driving vegetative growth and sucrose accumulation remains poorly understood. Herein, we carried out a comprehensive assessment of carbohydrate dynamics throughout the crop cycle in two sugarcane varieties varying in biomass production, evaluating the carbon metabolism in both leaves and stalks. Our data revealed that the decline in photosynthetic rates during sugarcane maturation is associated not only to accumulation of sugars in leaves but also due to stomatal and non-stomatal limitations. We found that metabolic processes in leaves and stalks were intrinsically linked. While IACSP94-2094 had higher stalk sucrose concentration than IACSP95-5000, this latter produced more biomass. Compared to IACSP95-5000, IACSP94-2094 showed higher sucrose phosphate synthase (SPS) activity in leaves and stalks, along with lower soluble acid invertase (SAI) activity in leaves during the maximum growth stage. Interestingly, IACSP94-2094 also exhibited higher stalk SPS activity and lower stalk SAI activity than IACSP95-5000 during maturation. High biomass production by IACSP95-5000 was associated with higher sucrose synthase (SuSy) and SAI activity in leaves and higher SuSy and soluble neutral invertase (SNI) activity in stalks when compared to IACSP94-2094 during the maximum growth. Despite the contrasting strategies, both varieties displayed similar total sucrose yield, a balance between sucrose concentration and biomass production. This phenomenon implies the presence of a compensatory mechanism in sugarcane, with high biomass production compensating low sucrose accumulation and vice versa.

A long-term field trial was conducted to determine yield trends in relation to nutrient uptake and efficiency in different rice-based cropping systems. The cropping systems had a significant effect on wet season rice yield when residues were not recycled but had no effect otherwise. Rice yield decreased after the first year of crop residue incorporation but increased every year thereafter. Rice yield was significantly affected by residual nutrients applied to dry season crops. The highest residual effect was observed in tomato and sweet pepper to which the highest nitrogen (N), phosphorus (P) and potassium (K) rates were applied. Maize, sweet pepper, and tomato responded well to NPK application, garlic had a low response and mungbean had no response. A relay crop served as a catch crop for excess nutrients and as shade to minimize sunscald effects for tomato and sweet pepper fruits.

The functional distribution of root activity was determined by selective placement of 32P at fixed positions from the base of the plant in five- and six-year-old acid lime (Kagzi Kalan) on Kama Khatta rootstock. Maximum recovery of radioactivity was observed within a 40 cm radius of the plant base and at depths of 24 cm in 1988 and 16 cm in 1989. Most root activity (75–80%) was confined within a radius of 80 cm and a depth of 16–24 cm. Application of fertilizer within this zone is therefore recommended for maximum utilization by the crop.

Actividad de las raíces en la lima acida

In a 4 × 4 × 4 NPK field experiment with coconut on a sandy soil, N increased girth, height and leaf production during the pre-bearing period, but phosphorus (up to 6½ years) and K (up to 3½ years) had no effect on any vegetative growth parameters. The rates of fertilizers for optimum copra and nut yield (13 to 16 years) were 0.35, 0.73 and 0.64 kg N, PO and KO/palm/ year respectively. The high P requirement was due to the low solubility of the saphos phosphate in these sandy soils. A positive N × P interaction was also observed.

Line sowing of jute has been advocated by some workers for the past 40 years as being more productive than the traditional broadcast method. But most cultivators still prefer broadcast sowing. A comparative study employing identical management practices showed that there is no significant difference in fibre yield per unit area between the two sowing methods. Under similar population pressures self-thinning is greater in line sown than in broadcast crops. Thus, provided similar seed rates and cultural conditions are maintained, farmers may use either sowing method.

P. Palit, A. C Bhattacharyya y B. K. Samanta: Re-evaluación de los efectos de la siembra al voleo y en lineas sobre el rendimiento defibra del yute.

The perennial grass Pennisetum polystachyon was grown alone or in mixture with the indigenous legumes Atylosia scarabaeoidesand Clitoria ternata and the exotic species Calopogonium mucunoides, Centrosema pubescens and Stylosanthes gracilis. Only the last two persisted for more than one or two years. Mean annual yield from the mixture containing Centrosema was 61 to 65 q./ha., of which 20 per cent was legume herbage. The protein content of grass was about 3 to 6 per cent and of legumes 10 to 14 per cent. Mixed swards produced as much protein as in a previous experiment where pure swards of Pennisetum polystachyon received 44. kg./ha. of nitrogen in fertilizer form. Soil nitrogen increased under the Centrosema mixture and yields from the mixture increased during the experiment. Yields of grass herbage from the mixtures were generally lower than those of the grass swards. The reduction in yield of grass grown in mixed swards was mostly due to decreases in the area of foliage rather than to reductions in net assimilation rate.

The effects of three irrigation regimes on growth, yield and quality of cotton were investigated for two seasons in relation to earliness, quality and water-use efficiency, expressed as m. of water/kg. cotton produced. Light irrigations of cotton, at 75 mm. per irrigation every ten days, were economically better than the traditionally-accepted practice of irrigating every 14 days, and markedly better than prolonging the irrigation cycle to 20 days, mainly due to increased market value of the crop. The results also showed that irrigation intervals of 20 days, besides depressing yield, had a deleterious effect on fibre strength, though the different water regimes did not seem to affect other quality tests.