Competition between neighbouring units in field experiments is a serious source of bias. The study of a competing situation needs construction of an environment in which it can happen and the competing units have to appear in a predetermined pattern. This paper describes methods of constructing incomplete block designs balanced for neighbouring competition effects. The designs obtained are totally balanced in the sense that all the effects, direct and neighbours, are estimated with the same variance. The efficiency of these designs has been computed as compared to a complete block design balanced for neighbours and a catalogue has also been prepared.Competition effects, circular design, totally balanced design, MOLS,
Improving the farming system to attain the household level self‐sufficiency, land utilization efficiency and sustainable livelihood security depends on better socio‐economic and ecological aspects of the systems practiced by the small farmers in the semiarid regions of India. The higher sustainable livelihood security index (SLSI) in the integrated crops‐livestock system helps to restore economic and ecological sustainability. The aim of this study was to analyze how various modules of farming in different combinations have interacted with the diversification of existing systems. We used the ecological security index (ESI), economic efficiency index (EEI), and social equity index (SEI) to produce a SLSI of improved integrated farming system (IFS) compared with benchmark farming in semiarid regions. In this study, different existing IFS comprising of seven modules (field crops, dairy, goats, poultry, horticulture, fishery, and apiary) in different combinations were examined. Results revealed that 72.5% farmers preferred to integrate two modules, where as 95% of farmers adopted field crops + dairy (FC + D) in preference to other modules. The sustainability indicators: ESI (+43.3%), EEI (+16.0%), SEI (+11.6%), and SLSI (+6.0%) were improved in the FC + D farming system to a greater degree than other IFS module combinations. Similarly, improved IFS interventions also increased sustainability indicators over benchmark farming. Based on large scale household studies over 5 years, our findings suggest that the improved IFS succeeded in providing a wider array of livelihood security than existing practices. Hence, the paradigm shift from component approach to an IFS‐based resilient system, which is economically viable, environmentally sustainable, and socially acceptable, is needed for development of semiarid regions.
A polycross is the pollination by natural hybridization of a group of genotypes, generally selected, grown in isolation from other compatible genotypes in such a way to promote random open pollination. A particular practical application of the polycross method occurs in the production of a synthetic variety resulting from cross-pollinated plants. Laying out these experiments in appropriate designs, known as polycross designs, would not only save experimental resources but also gather more information from the experiment. Different situations may arise in polycross nurseries where accordingly different polycross designs may be used. For situations in which some genotypes interfere in the growth or production of other genotypes, but have to be grown together, neighbour-restricted design is a better option. Furthermore, when the topography of the nursery is such that a known wind system in a certain direction may prevail, then designs balanced for neighbour effects of genotypes only in the direction of wind are appropriate which may help in saving experimental resources to a great extent. Also, when genotypes are planted in a small area without leaving much space between rows, designs balanced for neighbour effects from all possible eight directions are useful to have equal chance of pollinating and being pollinated by every other genotype. Here, polycross designs have been obtained to match above-mentioned three situations. SAS Macros have also been developed to generate these proposed designs.
Experimental designs in which treatments are applied to the experimental units, one at a time, in sequences over a number of periods, have been used in several scientific investigations and are known as repeated measurements designs. Besides direct effects, these designs allow estimation of residual effects of treatments along with adjustment for them. Assuming the existence of first-order residual effects of treatments, Hedayat & Afsarinejad (1975) gave a method of constructing minimal balanced repeated measurements [RM(v,n,p)] design for v treatments using n=2v experimental units for p [=(v+1)/2] periods when v is a prime or prime power. Here, a general method of construction of these designs for all odd v has been given along with an outline for their analysis. In terms of variances of estimated elementary contrasts between treatment effects (direct and residual), these designs are seen to be partially variance balanced based on the circular association scheme.
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