Screening of germplasm for specific traits is a continuous pre-breeding process in deriving the drought-tolerant donors required for crop improvement. The study evaluated 17 medium-late duration finger millet genotypes under drought stress (DS) for 28 days during the reproductive stage to identify the traits and genotypes for drought tolerance using different statistical analysis. The photosynthetic rate (by 26.3%), stomatal conductance (by 26.4%), transpiration rate (by 24.8%) and grain yield (by 13.2%) were decreased and found sensitive to DS, but the leaf temperature was increased (4.7%). From the path analysis and multiple linear regression analysis, the mean ear weight and productive tillers were found to contribute to the grain yield significantly under well-watered conditions. While under DS conditions, the mean ear weight, productive tillers and threshing percentage equally contributed to grain yield. Based on the ranking of traits significantly contributing to grain yield, the genotype GE-4683 with a higher mean ear weight (10.65 g) was found superior to the popular variety, GPU-28. The Multiple linear regression equation predicts the possibility to increase the yield of GPU-28 under DS from the existing 360.0 to 459.5 g per square metre (by 29.1%) by the incorporation of three productive tillers instead of the existing two tillers per plant in the MLR equation. An additional 1.0 g of mean ear weight will be able to predict an increased grain yield from 360.0 to 392.0 gm−2, equivalent to 3.60 to 3.92 t/ha (by 9.4%).

Finger millet is gaining importance as a food crop with the increasing emphasis on nutritional aspects and drought resilience. However, yield improvement has stagnated. Therefore, popular varieties have been examined for the purpose of whether direct selection for grain yield can be continued or an alternate trait-based approach using the germplasm is necessary. Direct selection for grain yield over the ruling variety, cv. GPU-28 (Germplasm Unit) has not been satisfactory. The path analysis has revealed a high direct effect of mean ear weight on grain yield followed by a moderate direct effect of photosynthetic rate and leaf area index. Furthermore, backward stepwise regression analysis revealed that among the independent traits, the mean ear weight made a significant contribution (60.8%) towards grain yield, followed by the photosynthetic rate (39.2%). The regression equation predicts the inclusion of mean ear weight by 1.0 g extra (as in GE-2672) to cv. GPU-28 will increase grain yield by 4.74%. The trait-specific genotypes are superior to the cv. GPU-28 were GPU-67 (photosynthetic rate) and GE-2672 (mean ear weight) and they could be used as donors for yield improvement. Future selection would aim for genotypes having 70–75 days for flowering with 4−5 productive tillers and mean ear weight of more than 8−9 g/ear. The possible approaches for enhancing grain yield are also discussed.

Plants started with seed, 'seedlings', and established plants of silverleaf nightshade (Solanum elaeagnifolium Cav.) were grown in the field under shade levels of 0, 47, 63, and 92% of full sunlight to determine vegetative, reproductive, and physiological responses to shade. Dry-matter production of both 'seedling’ and established plants declined markedly with increasing shade levels. Established plants did not bear fruit under 92% shade, and 63% shade prevented fruit production by 'seedlings'. Taproots of plants grown in full sunlight contained 16% more total non-structural carbohydrate (TNC) per gram dry weight than taproots of plants grown under 92% shade. Leaves of established plants grown under moderate shade had significantly more chlorophyll per unit leaf fresh weight than plants grown in full sunlight; however, plants under heavy (92%) shade had 35% less chlorophyll per unit leaf area than unshaded plants. The chlorophyll a/b ratio of the 92%-shaded plants was significantly less than with other treatments. Leaf area increased, with increasing shade; however, leaf weight per unit area decreased because of thinner leaves. Photosynthetic rates of recently expanded leaves were 10.4, 4.6, 3.3, and 0.9 mg CO2 · dm−2 · h−1 for the 0, 47, 63, and 92% shade treatments, respectively.

Experiments were conducted to investigate the acclimation of Palmer amaranth to shading. Plants were grown in the field beneath black shade cloths providing 47 and 87% shade and in full sunlight (no shading). All photosynthetic measurements were taken 4 wk after initiating the shade treatments. Photosynthetic rates of Palmer amaranth grown under 47% shade increased with increasing photosynthetic active radiation (PAR) similar to 0% shade-grown plants. Light-saturated photosynthetic rates were predicted beyond the highest measured PAR of 1,200 µmol m−2 s−1 for plants grown under 0 and 47% shade. Plants acclimated to increased shading by decreasing light-saturated photosynthetic rates from 60.5 µmol m−2 s−1 under full sun conditions to 26.4 µmol m−2 s−1 under 87% shade. Plants grown under 87% shade lowered their light compensation point. Rate of increase in plant height was similar among shade treatments. Plants responded to increased shading by a 13 to 44% reduction in leaf appearance rate (leaf number growing degree days [GDD]−1) and a 22 to 63% reduction in main-stem branch appearance rate (main-stem branch number GDD−1) compared with full sunlight. Palmer amaranth specific leaf area increased from 68 to 97 cm2 g−1 as shading increased to 87%. Plants acclimated to 47% shade by increasing total leaf chlorophyll from 22.8 µg cm−2 in full sunlight to 31.7 µg cm−2 when shaded; however, the increase was not significant at 87% shading. Thus, it is concluded that Palmer amaranth shows photosynthetic and morphological acclimation to 87% or less shading.