Determining nutrients limiting factors on grain yield and yield components to common beans (Phaseolus vulgaris L.) under drought and non-drought conditions

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Drought and soil fertility are some of the major factors limiting crop yield especially in crop legumes. Six on-station trials were conducted to determine nutrients limiting the grain yield and yield component in common beans (Phaseolus vulgaris L.) under drought and non-drought conditions at Kandiyani and Chitedze Research Station. Two trials were conducted at Chitedze Research Station under rainfed conditions: one using a climbing bean variety (MAC 53) and another using bush bean variety (SUG 131). The trials were repeated at Kandiyani under irrigation: one set of bush and climbing bean (2 trials) were evaluated under adequate moisture up to physiological maturity and another set (2 trials) was evaluated under moisture stress by cutting the water supply soon after flowering to simulate terminal drought.

The experiments were laid out in a split-plot treatment arrangement with 3 replicates. In each replicate 9, main plots (macronutrient factors) were allocated at random to each replicate, and within the main plot, 4 subplots (micronutrient factors) were allocated at random making a total of (9x4) 36 treatments in each replication. The macro-nutrient factors included: (1) control; (2) N; (3) P ; (4) K; (5) Ca; (6) N2-fixation –CIAT 899 Rhizobium (Rz); (7) NP, (8) NPRz; and (9) NPK. The sub-plots were: (1) control; (2) B; (3) Mo; and (4) ZnS.

There were significant interaction among macronutrient and micronutrient on grain yield.  Nitrogen, Phosphorus, Molybdenum with rhizobium inoculant (NPRz + Mo) resulted in significantly increased grain yield of beans, days to flowering, number, fresh weight of nodules number of pods and 100 seed weight.

Across water regime analysis on climbing beans showed that the macronutrients application had highly significant effects (P<0.001) on the number of days to flowering, number of pods per plant and grain yield per hectare, while macro-micronutrient combination had significant effect at P=0.005 level on days to flowering and highly significant effect (P<0.001) on the number of pods per plant.

In terms of drought tolerance efficiency (DTE) and drought susceptibility, P fertilizer treatment was observed to influence high drought tolerant efficient (DTE) also with smaller percentage of reduction (2%) under drought stress. However, NPK + Mo treatment was the best with smaller drought susceptibility index (DSI) on bush beans. Under climber beans, N+P and N+P+Rz were observed to be the best with high drought susceptibility index (DSI) among the 36 treatments.


MSc and Bcs thesis, internship reports

Mônea Lina Adelino Mucavêa