Search

The objective of this research was to compare selected ecophysiological parameters for a wheat crop found in the Indo-Gangetic Plains of India and its five dominant weeds. The dominant and regionally ubiquitous weeds in the wheat field that was selected for the study were Anagallis arvensis, Chenopodium album, Melilotus albus, Phalaris minor and Rumex dentatus. Taller weeds, such as C. album and P. minor, constituted one group along with the crop, with a low photosynthetic rate, specific leaf area, leaf nitrogen mass basis, chlorophyll content, photosynthetic nitrogen-use efficiency and leaf area ratio, in comparison to shorter weeds, such as A. arvensis, M. albus and R. dentatus, which formed another group with a high photosynthetic rate, specific leaf area, leaf nitrogen mass basis, chlorophyll content, photosynthetic nitrogen-use efficiency and leaf area ratio. Interspecific variations in the photosynthetic rate were driven mainly by variability in the specific leaf area and leaf nitrogen content. The taller weeds and the crop had a low specific leaf area later in the season, whereas the smaller weeds had a relatively high specific leaf area, which might be an adaptation to the shaded environment below the canopy. The result indicates that any weed management in the wheat fields of the Indo-Gangetic Plains will need two different approaches because of the different strategies followed by the two weed groups that were identified in the present study. [ABSTRACT FROM AUTHOR]

A replacement series study was conducted to evaluate the interference interactions between the weedsPhalaris minororRumex dentatusand wheat at two nutrient levels to test for changes in the competitive relationships of the weeds with varying nutrient availability. Plants were established in a mixture with proportions of 4:0, 3:1, 2:2, 1:3 and 0:4 (wheat: weed) plants per pot. The weeds exhibited clear differences in growth attributes and competition indices from wheat.Rumex dentatusshowed significantly higher values for all growth attributes, relative yield, aggressivity and biomass. Both weeds performed better than wheat at high nutrient levels. Nutrient stress changed the intensity of competition between weeds and wheat, but did not change the weeds’ positions in the hierarchy. Therefore, although the competitiveness ofP. minorandR. dentatusappears to be lower under poor nutrient conditions, they outcompete wheat irrespective of nutrient availability. Overall, the findings of the study suggest that wheat is more susceptible to resource competition fromR. dentatusthanP. minor. [ABSTRACT FROM PUBLISHER]

Examines the effects of wheat residue placement and chemical fertilizer on microbal biomass, Nitrogen-mineralization and crop yield. Nitrogen (N) ranges of different plots; Optimization of N-mineralization after treatment of wheat residue plus fertilizer; Comparison of biomass ranges between rice and lentil crops; Influence of the component combination on the increased activity of soil organic matter.

• Organic systems showed higher soil CO 2 efflux and microbial biomass. • Rice-husk ash amendment showed increase in soil pH. • Agronomic parameters are higher under mineral fertilizer applied systems. • Harvest index is higher under farm-yard manure, rice-husk ash and their combined amendment. • Rice-husk ash in combination to farm-yard manure can be used for continuous reduction of mineral fertilizers. Several alternative amendments like organic manure and biochar have been proposed for revitalizing the degrading soil viability and fertility for sustainable agriculture, globally. However, detailed field-scale studies focussing on the soil and agronomic parameters of crops under these amendments are limited in dry tropical ecosystems. Therefore, we studied the impact of various soil amendments viz., rice-husk ash (RHA) and farm-yard manure (FYM) along with mineral fertilizer on soil biophysical and agronomic parameters of wheat crop. We specifically explored the impact of the amendments on soil CO 2 efflux (SCE, under different growth stages) and the harvest index of wheat crop, which are considered as the key indicators of soil viability and agronomic efficiency, respectively. SCE, soil moisture, soil temperature, soil N, microbial biomass and soil pH were found significantly varying under different treatments (P < 0.05). SCE was found maximum under sole FYM applied and minimum under mineral fertilizer applied treatments, whereas RHA application lowered the SCE as compared to sole FYM application. Moreover, SCE showed variation with plant growth stages, and found maximum during stem elongation followed by heading stage whereas minimum during ripening stage. Soil moisture was found to have considerable regulation for the overall variation in SCE (r2 = 0.17; P = 0.04). In contrast to the soil properties, agronomic parameters (except harvest index) were found higher under mineral fertilizer applied treatments followed by sole FYM and combined FYM + RHA treatments, whereas sole RHA applied treatment showed minimum values. However, significant variations were observed only for harvest index, aboveground dry matter, grain and straw yields (P < 0.05). Further, harvest index was found highest under sole and combined FYM and RHA applied treatments whereas lowest in mineral fertilizer applied treatments. Soil C/N ratio (r2 = 0.16; P = 0.04) and panicle length (r2 = 0.18; P = 0.03), respectively as soil and agronomic parameters, have been found to have considerable control over harvest index. The findings revealed that soil viability is higher under sole FYM and combined FYM + RHA treatments whereas mineral fertilization enhances agronomic performance. Based on the studied two indicators, we conclude that both soil and agronomic sustainability can be maintained by using a combination of organic (FYM and RHA) fertilization with reduced inputs from mineral fertilizers. However, it further needs exploration for various soil and plant eco-physiological parameters of different crops at field level for wider adaptation in the dry tropical region. [ABSTRACT FROM AUTHOR]